Cold weather misfires and CEL, common issues $50 fix!
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So tis the season for the usual car runs rough on start up, misfires, CEL/MIL, stalling. Before you get too deep into this thread, I believe most of the data is relevant to the 325/330 models, or typical the 2.5L M52tu and 3.0L M54 engines also used in the E39 5 series and E85??Z4 series (however, it may be relevant to the 323/328 models as well, but part numbers will probably vary?), please check part number and application carefully before placing parts orders.
First suggestion to help you move in the proper direction is get your CEL/MIL codes read. Start a log and note the date, mileage and each trouble code. If there are freeze frame codes, note these as well. Then clear your codes, NOTE YOU WILL NEED AN ODBII SCAN TOOL TO CLEAR YOUR CODES, also NOTE IF YOU ARE NOT USING A BMW SPECIFIC SCAN TOOL (PEAKE, GT1, PA SOFT, CARSOFT, ETC.) YOU MAY ONLY GET A PARTIAL PICTURE OF WHAT CODES YOUR CAR MAY HAVE. The idea here is each time your CEL/MIL lights up, try to read, log and and clear your codes ASAP. This will help you identify what code(s) show up first and will help you narrow your problem before other codes show up and may mislead you.
If you do not have a code reader or scan tool, many auto parts stores (Auto Zone, Advance, Pep Boys, O'Rielly, Fisher, etc.) will allow you to borrow one and usually use it in their parking lot. Even if it does not support BMW specific codes, most of the problems I have documented fall within the generic OBDII powertrain error code group. Codes usually are in the format of Pxxxx, example P0174.
Please note that the bulk of this thread has to do with problems on cold start up and during idle situations. There have been a number of cases lately where codes P0171/P0174 are not triggered at idle, but at highway cruise speeds. I suggest you cover the bases with the very common solutions listed below, but if once you have cleared the obvious problems and if you are getting P0171/P0174 at highway cruise speeds only, then you are most likely not dealing with a standard intake or crankcase vacuum/air leak. I will be adding information to this thread in the near future for lean codes at highway cruise speeds
IMPORTANT INFORMATION
As mentioned above, the bulk of this thread has to do with idle based problems, usually caused by vacuum/air leaks, but we have started to see a few cars that owners have addressed all the obvious vacuum/air leaks and they are still getting mostly Lean codes, many times without DME misfire codes. In a number of these instances the problems only show up during highway cruising situations, the CEL will not trigger during start up or any in town sub 45 MPH driving. But once the car is brought up to highway cruise type speeds, a few cars are still triggering the CEL along with P0171 & P0174. In many of these cases the problem has been with soft failed MAF's that are under reporting the amount of intake air, therefore causing the mixtures to be adjusted lean, then triggering Lean P0171 & P0174. So in some cases you may have a soft failure on a MAF where the engine is misfiring and running poorly and/or in a limp mode without any specific CEL or DME trouble codes.
Some cases we have seen soft failures on fuel pumps and/or fuel filters that either the pressure regulators are not working correctly and possibly issues with the fuel pressure regulator vacuum hose, even restricted fuel filters with 80-120k miles of fuel passing through them. Some of the soft fail fuel pump failures are causing P0171/P0174 without misfire and may only happen off idle when cruising. Sometimes even causing idle surge and instability without triggering the CEL or codes. Please cover the basics and take care of simple things like spark plugs, fuel filter and fuel pressure regulator vacuum hoses before spending a lot of money on other parts.If you do not know the history on your spark plugs and fuel filter, it is probably time to change them!
FUEL PUMP ISSUES
This is not really part of the simple vacuum leak/hose problems that were originally outlined, but BEWARE there are soft failures on fuel pumps that can lead to intermittent hesitation, rough idle, misfires and stalling.
Suggest you check this link here for more info on fuel pump failures - http://forum.e46fanatics.com/showthr...501&highlight=
A PM replacement of the pump, fuel filter and fuel pump relay may be a good idea. Parts cost if you do your homework should be under $200 and take about 1 hour. The best pump prices are from www.bmaparts.com from what we have seen lately. Fuel filter pricing on Amazon is pretty good as well.
Other items to possibly consider, but may not have been identified as actual causes of lean codes are as follows: camshaft timing may be out of spec possibly due to prior cylinder head removal and/or timing chain work, VANOS seals possibly casing camshaft timing to be off, throttle body/TPS issues. These are things to consider and to look into, many of these issues have not been proven to be a cause of the lean codes, however, just additional items to think about. Also keep in mind that pre Cat O2 sensor health is also important for proper reporting of fuel mixtures. And the last thing to think about is engine to body grounding. If for some reason the ground path between the engine and body/DME is questionable, you again may have incorrect reporting of sensor date, therefore possibly causing problems with CEL and DME trouble codes. So look at the charging Voltages and check the engine to body grounds while under the hood. Camshaft position sensors are also known weak points in these cars and they can also soft fail causing incorrect camshaft position feedback, thereby causing the VANOS to not work properly and possibly impact performance enough to cause Lean codes to be triggered.
But in any event, I would start with reading the DME trouble codes and uses these as clues, check all the obvious source so vacuum leaks, replace known problem hoses, gaskets and intake boots, then see where this all leads you. Additionally many maintenance related items should also be addressed before jumping into more costly and difficult sensor replacement.
Most of the problems I mention in this thread trigger one or more of the follow codes, but not limited just to these codes:
P0171 = Fuel Trim, Bank1 System Too Lean
P0174 = Fuel Trim, Bank2 System Too Lean
P1083 = Fuel Control Limit Mixture Too Lean (Bank 1, Sensor 1)
P1085 = Fuel Control Limit Mixture Too Lean (Bank 2, Sensor 1)
P1090 = Pre Catalyst Fuel Trim Too Lean Bank #1
P1091 = Pre Catalyst Fuel Trim Too Lean Bank #2
P0300 = Random/Multiple Cylinder Misfire Detected
P0313 = Misfire Detected Low Fuel Level
P1342 = Misfire During Start Cylinder 1
P1343 = Misfire Cylinder #1 with Fuel Cut-Off
P1344 = Misfire During Start Cylinder 2
P1345 = Misfire Cylinder #2 with Fuel Cut-Off
P1346 = Misfire During Start Cylinder 3
P1347 = Misfire Cylinder #3 with Fuel Cut-Off
P1348 = Misfire During Start Cylinder 4
P1349 = Misfire Cylinder #4 with Fuel Cut-Off
P1350 = Misfire During Start Cylinder 5
P1351 = Misfire Cylinder #5 with Fuel Cut-Off
P1352 = Misfire During Start Cylinder 6
P1353 = Misfire Cylinder #6 with Fuel Cut-Off
P0301 = Cylinder 1 Misfire Detected
P0302 = Cylinder 2 Misfire Detected
P0303 = Cylinder 3 Misfire Detected
P0304 = Cylinder 4 Misfire Detected
P0305 = Cylinder 5 Misfire Detected
P0306 = Cylinder 6 Misfire Detected
P0491 = Secondary Air Injection System Insufficient Flow (Bank 1)
P0492 = Secondary Air Injection System Insufficient Flow (Bank 2)
P0441 = Evaporative Emissions System Incorrect Purge Flow
P0455 = Evaporative Emissions System Leak Detected (Large Leak)
P0456 = Evaporative Emissions System Leak Detected (Very Small Leak)
Below are some of the MOST common problems/solutions. There may be other things that cause similar problems, but these are fairly easy to check visually, cheap and easy repairs. Many owners tend to just want to have a high priced single solutions like MAF, O2 sensors, ICV, Coils, Fuel Pumps, keep in mind that some of these items may be a contributing factor, however, it does not matter how many $100-$200 parts you throw on the car, if you have rubber hoses and gaskets leaking air, all the hard parts in the world will not solve your problems, they may help, but why not check the simple and cheaper things first, then check them off your list before you move forward. Except for the DISA O-ring, most of the other things can be visually inspected and tested very simply without a lot of dis-assembly. You can then rule these items in or out as potential problems within a few minutes if you know exactly what to look for.
Many of these problems are due to intake air leaks and/or crankcase air leaks of some sort, usually due to loose, damaged, broken or deteriorated parts, most likely rubber or plastic. Do not rule out crankcase leaks as the design of the engine keeps the crankcase under a small vacuum most of the time. A crankcase air leak is basically an intake air leak in these cars. The problem could be as simple as a dipstick not fully seated, a bad or loose oil fill car or a bad valve cover gasket or cracked valve cover that does not leak oil but can leak air/vacuum. Also in more extreme cases you can have vacuum leaks at the intake manifold to cylinder head connection. These gaskets have silicon rubber seals that can get heat set in the compressed state and leak only on cold start up situations.
A few ways to find and locate vacuum/air leaks is with a smoke tester (Internet search for more on smoke testers), using additional vacuum hose and using smoke inhaled from a cigarette or cigar, then blowing it into the vacuum hose to fill the intake or other vacuum lines, using a mechanics stethoscope with the transducer removed so you have open hose to you ears to attempt to locate a vacuum leak source while the engine is running, a 4 foot piece of hose to hold up to your ear to listen for vacuum leaks when the engine is running, and last but not least is a can of spray brake cleaner to spray and pinpoint vacuum leaks while the the engine is running. The spray brake cleaner will cause the engine RPM to increase slightly and smooth out when a leak is pinpointed. I have found via experience that very small and hard to find vacuum leaks, like where an intake manifold meets the cylinder head can be found much easily with spray brake cleaner than smoke testing or other methods. Also a note on smoke testing, many people swear by these, however, in practical terms, the smoke tester usually operate on very low pressure, usually 2-5 psi, they are usually only good for locating very obvious leaks that you should be able to find with visual inspection if you know where to look. I find that smoke testing may not show very difficult leaks like silicon gasketed surfaces such as the DISA or intake to cylinder head mating surfaces, this is where sometimes spray brake cleaner works much better. Be careful with spray brake cleaner on painted surfaces, breathing the fumes too much or getting it in your eyes due to splash back or air flow off the engine cooling fan. Use your head and be safe while working under the hood with the engine running, watch out for moving and hot parts, be aware of high Voltage ignition components and spraying flammable chemicals around!
Not in any specific order, but if you own an E46 (Actually almost any 6 cylinder BMW prior to the cut over to the e9x series models in 2005/2006), they are old enough now that these items should be replaced soon anyway. Please verify correct part numbers @ www.realoem.com to make sure you purchase and have the correct part numbers for your vehicle repair.
Here is a good link that has a complete DIY with pictures for most of the items listed below - http://forum.e46fanatics.com/showthr...&highlight=ccv
1. DISA Valve (sometimes referred to as an Adjuster Unit) #7 in this link - http://realoem.com/bmw/showparts.do?...79&hg=11&fg=40. The DISA has a number of different failure modes, the DISA can have problems anywhere from vacuum leaks to catastrophic failure that may leave butterfly floating loose in the intake plenum and possibly the rear metal pivot pin could fall out and be sucked into once of the cylinders causing pretty severe engine damage.
SPECIAL NOTE ON THE REAR DISA PIN - The rear DISA pin can and will fall out depending on how badly the DISA butterfly plate is worn on the actuator shaft. This metal pin appears to be pressed into the rear of the butterfly and rotates with the butterfly plate. If the butterfly has become cracked or is overly loose on the actuator shaft, this metal pin (about 1/4" in diameter and about 13/16" long) could possibly become loose, fall out of the DISA assembly and work its way into a cylinder and may possibly cause severe engine damage. If you remove the DISA, immediately look for the rear metal butterfly pin and make sure it is still firmly pressed in. If you do not find the pin, check the intake VERY carefully for the pin and remove it if you find it. If you find the pin and it is loose in anyway, please remove the DISA flap and rear metal pin if you need to reinstall the existing, worn out DISA until you can purchase and install a new DISA
The first thing you want do is remove the DISA valve, pretty easy overall, remove the intake air filter box, upper intake boot and a few wire connectors and you are ready to access the DISA, you will need the Torx bit to actually remove the 2 DISA mounting screws. Once the DISA screws are removed, ease the DISA out of the intake, do not force it, there is only 1 angle that the DISA will likely come out and go back into the intake, it is not hard once you find the proper angle.
If the DISA valve slides out of the intake the first 1/4" easy, without much effort, or almost falls out, you will need a new O-ring!
Now that you have the DISA out of the intake, you need to check other functions to make sure you even want to re-use the DISA long term.
Special note for inspecting DISA valve, while you have the DISA out, inspect the DISA for proper operation. The DISA butterfly should be spring loaded in the open position and the butteryfly should not be overly loose or sloppy in the DISA shaft. You can also shake the DISA and it should not be noisy (new DISA will make absolutely no noise or rattle if shaken VERY hard). If you have any noise when shaking the DISA, something is most like worn and/or broken and you should consider a replacement DISA. Also the DISA rear pin can fall out into the engine and the DISA butterfly valve can fall off and get stuck in the intake possibly blocking the airflow to 1 or more cylinders, so it you remove the DISA and see no butterfly flap or rear metal pin, get worried and start looking for spare parts in the intake. If you are lucky the rear metal pin will be in the DISA groove in the intake.
Keep this in mind in case you suspect your car may have already had a replacement DISA, and if you have some strange performance issues, maybe someone left the old butterfly in the intake manifold if it fell off the original DISA??
The DISA is vacuum controlled and the small vacuum actuator on the end of the DISA is what actually moves the butterfly valve along with a control solenoid. Overall the DISA is a very ingenious device. The large body is actually vacuum reservoir. If look closely there is a very small hole near the butterfly valve this is the actual vacuum source. To verify if the vacuum actuator is still working and not leaking, close the DISA butterfly with your hand and then put your thumb over the opening that is opposite side of the electric connector on the solenoid. What should happen is the DISA butterfly will spring back open about 1/4" beyond the DISA frame. If the butterfly pops all the way back to the open position or slowly moves back to the default open position, then the vacuum actuator diaphragm is leaking and the DISA will not function correctly.
While there may be some sources that offer DISA "rebuild" kits, I would stay away from them personally. The butterfly valve and shaft are only part of the DISA, there is also an electrically controlled solenoid, actuator shaft seal and a vacuum diaphragm that actually moves the DISA valve and these parts can and will fail. The shaft/butterfly failure usually happens sometimes after the 100k mile mark, so if you car has the original DISA still, it is most likely ready for a replacement by now anyway. The vacuum diaphragm is more likely to fail than the solenoid and if the vacuum diaphragm fails you will end up with ANOTHER hard to find vacuum leak. There have also been a few reports of DISA vacuum actuators that test fine before the DISA repair kit was installed, but after removing the shaft and butterfly valve, after the vacuum actuator link was tweaked and twisted, the vacuum diaphragm was then cracked and no longer properly held vacuum. This is kind of expected from a decade old flexible rubber diaphragm, so just beware and be forewarned. If you are reading this thread, your car is clearly old enough now that if the butterfly is loose on the shaft or the DISA rattles when you shake it, just do yourself a favor and buy a new DISA and be done with your problem DISA for the next 7-10 years.
If you feel the DISA is physically in good shape and the vacuum diaphragm for the actuator is still in good shape and holds vacuum, then you may just need to replace the primary O-ring, which is not typically serviceable, however, you can get a red silicon replacement on for under $12 online or someone mentioned you might be able to match up something at your local parts store. Recommend a silicon O-ring as it is a bit softer than some of the harder rubber compounds and will tend to seal better with the plastic expansion and contraction over wide temperatures. I would be so inclined to put this replacement on a new DISA anyway as the DISA seal is only good for about 5 years/50k miles, after than you are on borrowed time. If for some reason you remove the DISA to replace the lower intake boot or do other work on the car, REPLACE the O-ring or you will be sorry once it gets below 40F. Trust me.
If you think your DISA should be replaced, following are some of the most common part number, but please check the part number before ordering a replacement for your vehicle. DISA prices online are between $175-$225 depending on the part number and the supplier. Prices change, however, check www.bmwmercedesparts.com for pricing as if this entry they have the 3.0 L DISA for $176.
DISA BMW part number - Please verify these via www.realoem.com to confirm proper application.
325/2.5L engines appear to use BMW Part #11617544806, this appears to have superseded an earlier BMW Part #11617502269
330/3.0L engines appear to use BMW Part #11617544805, this appears to have superseded an earlier BMW Part #11617502275
Both of the 325/330 DISA's have the injected or mold orange silicon main seal. SPECIAL NOTE - The 325 and 330 DISA appear to be very close in size, the main intake hole opening is the same size, however, the 325 DISA will fit into a 330 intake opening, but not the other way around. The 330 DISA is about 1/2" longer overall. Make sure you did not or do not end up with the 325 DISA in a 330 intake. I believe the 330 DISA will bottom out in the 325 intake before the flange meets the intake surface. As a point of reference, the last 7 digits of the DISA part number will be cast into the side of the DISA next to a BMW logo. So a 325 DISA should have either 7502269 for the original part up through 4/04 or 7544806 for the newer version used after 4/04. The 330/3.0L DISA should have either 7502275 for the original part up through 4/04 or 7544805 for the newer version used after 4/04.
Taller (left side) DISA is for 3.0L engines, Shorter (right side) DISA is for 2.5L engines.
323/328 2.3L & 2.8L engines use DISA BMW part number - 11611440049, with the green removable O-ring. I have not confirmed for sure that the 2.3L/2.8L DISA has the part number cast into the side, but if it did, I assume it would have 1440049 after the BMW logo on the side of the DISA? Please verify part number and application.
Please verify part numbers @ www.realoem.com to verify proper part application for your vehicle!
If you feel your DISA is still serviceable, then I definitely suggest replacing the primary O-ring. Again, please measure your DISA and/or make sure when you order a replacement O-ring to specify your engine model as there are differences between the 323/328 & 325/330 series engines.
Note about the O-ring replacement, the 325/330 DISA has an orange molded/injected silicon seal in the groove, the 323/328 engines have a standard replaceable green O-ring. On the 325/330 you need to take a small screw driver and maybe a brass wire brush to scrape the groove clear of the original silicon before installing the new replacement O-ring. Then lube the O-ring with some silicon spray or clean light oil before reinstalling the DISA. The DISA will take some effort to seat it the last 1/4".
I do not suggest using any sort of sealer on the DISA O-ring area. There is an issue where the material needs to expand and contract to seal over temperature and any sort of sealer will not really work for the type of interface where this needs to seal in the inside of the hole in the intake manifold. What will happen is any sort of sealer will likely just make a mess that will need to be cleaned up once a proper O-ring has been installed.
PLEASE MAKE SURE YOU HAVE CLEARLY READ THE DISA SPECIAL NOTE ABOVE ABOUT THE REAR METAL BUTTERFLY PIN, WARNING, THIS PIN CAN FALL OUT ON EXTREMELY WORN DISA'S AND POTENTIAL CAUSE SEVERE ENGINE DAMAGE IF SUCKED INTO A CYLINDER
Sources for DISA O-ring
323/328 M52 Engines - Green removable O-ring
BMW Part #11617504543, this is a serviceable part for these engines.
http://www.ecstuning.com/BMW-E46-328.../Disa/ES25713/ -
Your local auto parts suppliers may have something that fits?? Examples - Auto Zone, Advance, Pep Boys, O'Rielly, Fisher, but this may be a wild goose chase and it would probably be better to order the O-ring online so you will get something a bit closer in fit.
For the 325/330 M54 engines, the DISA O-ring is not a serviceable part, you have to remove the orange injected/molded silicon sealer and clean the groove out and install a replacement O-ring.
http://germanautosolutions.com/DISA_O-Rings.html
DISA O-rings for 325/330 engines have the following dimensions.
Some manufactures have an O-ring sizing chart. O-rings referenced as -136, -137, -138, -139 should all work. These sizes are 3/32" thick and range from 2" to 2 3/16" I.D.
Thickness - 3/32" (do not suggest anything thicker)
I.D. - 2" - 2 3/16"
O.D. - 2 3/16" - 2 3/8"
Preferred material - silicon, however, rubber may substitute
Thickness - 2.5 mm (do not suggest anything thicker)
I.D. - 51mm - 55 mm
O.D. - 55mm - 60 mm
Preferred material - silicon, however, rubber may substitute
DISA O-rings for the 323/328 engines have the following dimensions.This is for DISA's with the green, removable O-ring, not the orange molded seal. I also believe that the green O-ring DISA's are less problematic than the DISA's with the orange molded seal?
Again this is a BMW serviceable part, part number 11617504543.
Thickness - 1/8"
I.D. - 2"
O.D. - 2 1/4"
Preferred material - silicon, however, rubber may substitute
Thickness - 5.5 mm
I.D. - 51 mm
O.D. - 62 mm
Preferred material - silicon, however, rubber may substitute
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So tis the season for the usual car runs rough on start up, misfires, CEL/MIL, stalling. Before you get too deep into this thread, I believe most of the data is relevant to the 325/330 models, or typical the 2.5L M52tu and 3.0L M54 engines also used in the E39 5 series and E85??Z4 series (however, it may be relevant to the 323/328 models as well, but part numbers will probably vary?), please check part number and application carefully before placing parts orders.
First suggestion to help you move in the proper direction is get your CEL/MIL codes read. Start a log and note the date, mileage and each trouble code. If there are freeze frame codes, note these as well. Then clear your codes, NOTE YOU WILL NEED AN ODBII SCAN TOOL TO CLEAR YOUR CODES, also NOTE IF YOU ARE NOT USING A BMW SPECIFIC SCAN TOOL (PEAKE, GT1, PA SOFT, CARSOFT, ETC.) YOU MAY ONLY GET A PARTIAL PICTURE OF WHAT CODES YOUR CAR MAY HAVE. The idea here is each time your CEL/MIL lights up, try to read, log and and clear your codes ASAP. This will help you identify what code(s) show up first and will help you narrow your problem before other codes show up and may mislead you.
If you do not have a code reader or scan tool, many auto parts stores (Auto Zone, Advance, Pep Boys, O'Rielly, Fisher, etc.) will allow you to borrow one and usually use it in their parking lot. Even if it does not support BMW specific codes, most of the problems I have documented fall within the generic OBDII powertrain error code group. Codes usually are in the format of Pxxxx, example P0174.
Please note that the bulk of this thread has to do with problems on cold start up and during idle situations. There have been a number of cases lately where codes P0171/P0174 are not triggered at idle, but at highway cruise speeds. I suggest you cover the bases with the very common solutions listed below, but if once you have cleared the obvious problems and if you are getting P0171/P0174 at highway cruise speeds only, then you are most likely not dealing with a standard intake or crankcase vacuum/air leak. I will be adding information to this thread in the near future for lean codes at highway cruise speeds
IMPORTANT INFORMATION
As mentioned above, the bulk of this thread has to do with idle based problems, usually caused by vacuum/air leaks, but we have started to see a few cars that owners have addressed all the obvious vacuum/air leaks and they are still getting mostly Lean codes, many times without DME misfire codes. In a number of these instances the problems only show up during highway cruising situations, the CEL will not trigger during start up or any in town sub 45 MPH driving. But once the car is brought up to highway cruise type speeds, a few cars are still triggering the CEL along with P0171 & P0174. In many of these cases the problem has been with soft failed MAF's that are under reporting the amount of intake air, therefore causing the mixtures to be adjusted lean, then triggering Lean P0171 & P0174. So in some cases you may have a soft failure on a MAF where the engine is misfiring and running poorly and/or in a limp mode without any specific CEL or DME trouble codes.
Some cases we have seen soft failures on fuel pumps and/or fuel filters that either the pressure regulators are not working correctly and possibly issues with the fuel pressure regulator vacuum hose, even restricted fuel filters with 80-120k miles of fuel passing through them. Some of the soft fail fuel pump failures are causing P0171/P0174 without misfire and may only happen off idle when cruising. Sometimes even causing idle surge and instability without triggering the CEL or codes. Please cover the basics and take care of simple things like spark plugs, fuel filter and fuel pressure regulator vacuum hoses before spending a lot of money on other parts.If you do not know the history on your spark plugs and fuel filter, it is probably time to change them!
FUEL PUMP ISSUES
This is not really part of the simple vacuum leak/hose problems that were originally outlined, but BEWARE there are soft failures on fuel pumps that can lead to intermittent hesitation, rough idle, misfires and stalling.
Suggest you check this link here for more info on fuel pump failures - http://forum.e46fanatics.com/showthr...501&highlight=
A PM replacement of the pump, fuel filter and fuel pump relay may be a good idea. Parts cost if you do your homework should be under $200 and take about 1 hour. The best pump prices are from www.bmaparts.com from what we have seen lately. Fuel filter pricing on Amazon is pretty good as well.
Other items to possibly consider, but may not have been identified as actual causes of lean codes are as follows: camshaft timing may be out of spec possibly due to prior cylinder head removal and/or timing chain work, VANOS seals possibly casing camshaft timing to be off, throttle body/TPS issues. These are things to consider and to look into, many of these issues have not been proven to be a cause of the lean codes, however, just additional items to think about. Also keep in mind that pre Cat O2 sensor health is also important for proper reporting of fuel mixtures. And the last thing to think about is engine to body grounding. If for some reason the ground path between the engine and body/DME is questionable, you again may have incorrect reporting of sensor date, therefore possibly causing problems with CEL and DME trouble codes. So look at the charging Voltages and check the engine to body grounds while under the hood. Camshaft position sensors are also known weak points in these cars and they can also soft fail causing incorrect camshaft position feedback, thereby causing the VANOS to not work properly and possibly impact performance enough to cause Lean codes to be triggered.
But in any event, I would start with reading the DME trouble codes and uses these as clues, check all the obvious source so vacuum leaks, replace known problem hoses, gaskets and intake boots, then see where this all leads you. Additionally many maintenance related items should also be addressed before jumping into more costly and difficult sensor replacement.
Most of the problems I mention in this thread trigger one or more of the follow codes, but not limited just to these codes:
P0171 = Fuel Trim, Bank1 System Too Lean
P0174 = Fuel Trim, Bank2 System Too Lean
P1083 = Fuel Control Limit Mixture Too Lean (Bank 1, Sensor 1)
P1085 = Fuel Control Limit Mixture Too Lean (Bank 2, Sensor 1)
P1090 = Pre Catalyst Fuel Trim Too Lean Bank #1
P1091 = Pre Catalyst Fuel Trim Too Lean Bank #2
P0300 = Random/Multiple Cylinder Misfire Detected
P0313 = Misfire Detected Low Fuel Level
P1342 = Misfire During Start Cylinder 1
P1343 = Misfire Cylinder #1 with Fuel Cut-Off
P1344 = Misfire During Start Cylinder 2
P1345 = Misfire Cylinder #2 with Fuel Cut-Off
P1346 = Misfire During Start Cylinder 3
P1347 = Misfire Cylinder #3 with Fuel Cut-Off
P1348 = Misfire During Start Cylinder 4
P1349 = Misfire Cylinder #4 with Fuel Cut-Off
P1350 = Misfire During Start Cylinder 5
P1351 = Misfire Cylinder #5 with Fuel Cut-Off
P1352 = Misfire During Start Cylinder 6
P1353 = Misfire Cylinder #6 with Fuel Cut-Off
P0301 = Cylinder 1 Misfire Detected
P0302 = Cylinder 2 Misfire Detected
P0303 = Cylinder 3 Misfire Detected
P0304 = Cylinder 4 Misfire Detected
P0305 = Cylinder 5 Misfire Detected
P0306 = Cylinder 6 Misfire Detected
P0491 = Secondary Air Injection System Insufficient Flow (Bank 1)
P0492 = Secondary Air Injection System Insufficient Flow (Bank 2)
P0441 = Evaporative Emissions System Incorrect Purge Flow
P0455 = Evaporative Emissions System Leak Detected (Large Leak)
P0456 = Evaporative Emissions System Leak Detected (Very Small Leak)
Below are some of the MOST common problems/solutions. There may be other things that cause similar problems, but these are fairly easy to check visually, cheap and easy repairs. Many owners tend to just want to have a high priced single solutions like MAF, O2 sensors, ICV, Coils, Fuel Pumps, keep in mind that some of these items may be a contributing factor, however, it does not matter how many $100-$200 parts you throw on the car, if you have rubber hoses and gaskets leaking air, all the hard parts in the world will not solve your problems, they may help, but why not check the simple and cheaper things first, then check them off your list before you move forward. Except for the DISA O-ring, most of the other things can be visually inspected and tested very simply without a lot of dis-assembly. You can then rule these items in or out as potential problems within a few minutes if you know exactly what to look for.
Many of these problems are due to intake air leaks and/or crankcase air leaks of some sort, usually due to loose, damaged, broken or deteriorated parts, most likely rubber or plastic. Do not rule out crankcase leaks as the design of the engine keeps the crankcase under a small vacuum most of the time. A crankcase air leak is basically an intake air leak in these cars. The problem could be as simple as a dipstick not fully seated, a bad or loose oil fill car or a bad valve cover gasket or cracked valve cover that does not leak oil but can leak air/vacuum. Also in more extreme cases you can have vacuum leaks at the intake manifold to cylinder head connection. These gaskets have silicon rubber seals that can get heat set in the compressed state and leak only on cold start up situations.
A few ways to find and locate vacuum/air leaks is with a smoke tester (Internet search for more on smoke testers), using additional vacuum hose and using smoke inhaled from a cigarette or cigar, then blowing it into the vacuum hose to fill the intake or other vacuum lines, using a mechanics stethoscope with the transducer removed so you have open hose to you ears to attempt to locate a vacuum leak source while the engine is running, a 4 foot piece of hose to hold up to your ear to listen for vacuum leaks when the engine is running, and last but not least is a can of spray brake cleaner to spray and pinpoint vacuum leaks while the the engine is running. The spray brake cleaner will cause the engine RPM to increase slightly and smooth out when a leak is pinpointed. I have found via experience that very small and hard to find vacuum leaks, like where an intake manifold meets the cylinder head can be found much easily with spray brake cleaner than smoke testing or other methods. Also a note on smoke testing, many people swear by these, however, in practical terms, the smoke tester usually operate on very low pressure, usually 2-5 psi, they are usually only good for locating very obvious leaks that you should be able to find with visual inspection if you know where to look. I find that smoke testing may not show very difficult leaks like silicon gasketed surfaces such as the DISA or intake to cylinder head mating surfaces, this is where sometimes spray brake cleaner works much better. Be careful with spray brake cleaner on painted surfaces, breathing the fumes too much or getting it in your eyes due to splash back or air flow off the engine cooling fan. Use your head and be safe while working under the hood with the engine running, watch out for moving and hot parts, be aware of high Voltage ignition components and spraying flammable chemicals around!
Not in any specific order, but if you own an E46 (Actually almost any 6 cylinder BMW prior to the cut over to the e9x series models in 2005/2006), they are old enough now that these items should be replaced soon anyway. Please verify correct part numbers @ www.realoem.com to make sure you purchase and have the correct part numbers for your vehicle repair.
Here is a good link that has a complete DIY with pictures for most of the items listed below - http://forum.e46fanatics.com/showthr...&highlight=ccv
1. DISA Valve (sometimes referred to as an Adjuster Unit) #7 in this link - http://realoem.com/bmw/showparts.do?...79&hg=11&fg=40. The DISA has a number of different failure modes, the DISA can have problems anywhere from vacuum leaks to catastrophic failure that may leave butterfly floating loose in the intake plenum and possibly the rear metal pivot pin could fall out and be sucked into once of the cylinders causing pretty severe engine damage.
SPECIAL NOTE ON THE REAR DISA PIN - The rear DISA pin can and will fall out depending on how badly the DISA butterfly plate is worn on the actuator shaft. This metal pin appears to be pressed into the rear of the butterfly and rotates with the butterfly plate. If the butterfly has become cracked or is overly loose on the actuator shaft, this metal pin (about 1/4" in diameter and about 13/16" long) could possibly become loose, fall out of the DISA assembly and work its way into a cylinder and may possibly cause severe engine damage. If you remove the DISA, immediately look for the rear metal butterfly pin and make sure it is still firmly pressed in. If you do not find the pin, check the intake VERY carefully for the pin and remove it if you find it. If you find the pin and it is loose in anyway, please remove the DISA flap and rear metal pin if you need to reinstall the existing, worn out DISA until you can purchase and install a new DISA
The first thing you want do is remove the DISA valve, pretty easy overall, remove the intake air filter box, upper intake boot and a few wire connectors and you are ready to access the DISA, you will need the Torx bit to actually remove the 2 DISA mounting screws. Once the DISA screws are removed, ease the DISA out of the intake, do not force it, there is only 1 angle that the DISA will likely come out and go back into the intake, it is not hard once you find the proper angle.
If the DISA valve slides out of the intake the first 1/4" easy, without much effort, or almost falls out, you will need a new O-ring!
Now that you have the DISA out of the intake, you need to check other functions to make sure you even want to re-use the DISA long term.
Special note for inspecting DISA valve, while you have the DISA out, inspect the DISA for proper operation. The DISA butterfly should be spring loaded in the open position and the butteryfly should not be overly loose or sloppy in the DISA shaft. You can also shake the DISA and it should not be noisy (new DISA will make absolutely no noise or rattle if shaken VERY hard). If you have any noise when shaking the DISA, something is most like worn and/or broken and you should consider a replacement DISA. Also the DISA rear pin can fall out into the engine and the DISA butterfly valve can fall off and get stuck in the intake possibly blocking the airflow to 1 or more cylinders, so it you remove the DISA and see no butterfly flap or rear metal pin, get worried and start looking for spare parts in the intake. If you are lucky the rear metal pin will be in the DISA groove in the intake.
Keep this in mind in case you suspect your car may have already had a replacement DISA, and if you have some strange performance issues, maybe someone left the old butterfly in the intake manifold if it fell off the original DISA??
The DISA is vacuum controlled and the small vacuum actuator on the end of the DISA is what actually moves the butterfly valve along with a control solenoid. Overall the DISA is a very ingenious device. The large body is actually vacuum reservoir. If look closely there is a very small hole near the butterfly valve this is the actual vacuum source. To verify if the vacuum actuator is still working and not leaking, close the DISA butterfly with your hand and then put your thumb over the opening that is opposite side of the electric connector on the solenoid. What should happen is the DISA butterfly will spring back open about 1/4" beyond the DISA frame. If the butterfly pops all the way back to the open position or slowly moves back to the default open position, then the vacuum actuator diaphragm is leaking and the DISA will not function correctly.
While there may be some sources that offer DISA "rebuild" kits, I would stay away from them personally. The butterfly valve and shaft are only part of the DISA, there is also an electrically controlled solenoid, actuator shaft seal and a vacuum diaphragm that actually moves the DISA valve and these parts can and will fail. The shaft/butterfly failure usually happens sometimes after the 100k mile mark, so if you car has the original DISA still, it is most likely ready for a replacement by now anyway. The vacuum diaphragm is more likely to fail than the solenoid and if the vacuum diaphragm fails you will end up with ANOTHER hard to find vacuum leak. There have also been a few reports of DISA vacuum actuators that test fine before the DISA repair kit was installed, but after removing the shaft and butterfly valve, after the vacuum actuator link was tweaked and twisted, the vacuum diaphragm was then cracked and no longer properly held vacuum. This is kind of expected from a decade old flexible rubber diaphragm, so just beware and be forewarned. If you are reading this thread, your car is clearly old enough now that if the butterfly is loose on the shaft or the DISA rattles when you shake it, just do yourself a favor and buy a new DISA and be done with your problem DISA for the next 7-10 years.
If you feel the DISA is physically in good shape and the vacuum diaphragm for the actuator is still in good shape and holds vacuum, then you may just need to replace the primary O-ring, which is not typically serviceable, however, you can get a red silicon replacement on for under $12 online or someone mentioned you might be able to match up something at your local parts store. Recommend a silicon O-ring as it is a bit softer than some of the harder rubber compounds and will tend to seal better with the plastic expansion and contraction over wide temperatures. I would be so inclined to put this replacement on a new DISA anyway as the DISA seal is only good for about 5 years/50k miles, after than you are on borrowed time. If for some reason you remove the DISA to replace the lower intake boot or do other work on the car, REPLACE the O-ring or you will be sorry once it gets below 40F. Trust me.
If you think your DISA should be replaced, following are some of the most common part number, but please check the part number before ordering a replacement for your vehicle. DISA prices online are between $175-$225 depending on the part number and the supplier. Prices change, however, check www.bmwmercedesparts.com for pricing as if this entry they have the 3.0 L DISA for $176.
DISA BMW part number - Please verify these via www.realoem.com to confirm proper application.
325/2.5L engines appear to use BMW Part #11617544806, this appears to have superseded an earlier BMW Part #11617502269
330/3.0L engines appear to use BMW Part #11617544805, this appears to have superseded an earlier BMW Part #11617502275
Both of the 325/330 DISA's have the injected or mold orange silicon main seal. SPECIAL NOTE - The 325 and 330 DISA appear to be very close in size, the main intake hole opening is the same size, however, the 325 DISA will fit into a 330 intake opening, but not the other way around. The 330 DISA is about 1/2" longer overall. Make sure you did not or do not end up with the 325 DISA in a 330 intake. I believe the 330 DISA will bottom out in the 325 intake before the flange meets the intake surface. As a point of reference, the last 7 digits of the DISA part number will be cast into the side of the DISA next to a BMW logo. So a 325 DISA should have either 7502269 for the original part up through 4/04 or 7544806 for the newer version used after 4/04. The 330/3.0L DISA should have either 7502275 for the original part up through 4/04 or 7544805 for the newer version used after 4/04.
Taller (left side) DISA is for 3.0L engines, Shorter (right side) DISA is for 2.5L engines.323/328 2.3L & 2.8L engines use DISA BMW part number - 11611440049, with the green removable O-ring. I have not confirmed for sure that the 2.3L/2.8L DISA has the part number cast into the side, but if it did, I assume it would have 1440049 after the BMW logo on the side of the DISA? Please verify part number and application.
Please verify part numbers @ www.realoem.com to verify proper part application for your vehicle!
If you feel your DISA is still serviceable, then I definitely suggest replacing the primary O-ring. Again, please measure your DISA and/or make sure when you order a replacement O-ring to specify your engine model as there are differences between the 323/328 & 325/330 series engines.
Note about the O-ring replacement, the 325/330 DISA has an orange molded/injected silicon seal in the groove, the 323/328 engines have a standard replaceable green O-ring. On the 325/330 you need to take a small screw driver and maybe a brass wire brush to scrape the groove clear of the original silicon before installing the new replacement O-ring. Then lube the O-ring with some silicon spray or clean light oil before reinstalling the DISA. The DISA will take some effort to seat it the last 1/4".
I do not suggest using any sort of sealer on the DISA O-ring area. There is an issue where the material needs to expand and contract to seal over temperature and any sort of sealer will not really work for the type of interface where this needs to seal in the inside of the hole in the intake manifold. What will happen is any sort of sealer will likely just make a mess that will need to be cleaned up once a proper O-ring has been installed.
PLEASE MAKE SURE YOU HAVE CLEARLY READ THE DISA SPECIAL NOTE ABOVE ABOUT THE REAR METAL BUTTERFLY PIN, WARNING, THIS PIN CAN FALL OUT ON EXTREMELY WORN DISA'S AND POTENTIAL CAUSE SEVERE ENGINE DAMAGE IF SUCKED INTO A CYLINDER
Sources for DISA O-ring
323/328 M52 Engines - Green removable O-ring
BMW Part #11617504543, this is a serviceable part for these engines.
http://www.ecstuning.com/BMW-E46-328.../Disa/ES25713/ -
Your local auto parts suppliers may have something that fits?? Examples - Auto Zone, Advance, Pep Boys, O'Rielly, Fisher, but this may be a wild goose chase and it would probably be better to order the O-ring online so you will get something a bit closer in fit.
For the 325/330 M54 engines, the DISA O-ring is not a serviceable part, you have to remove the orange injected/molded silicon sealer and clean the groove out and install a replacement O-ring.
http://germanautosolutions.com/DISA_O-Rings.html
DISA O-rings for 325/330 engines have the following dimensions.
Some manufactures have an O-ring sizing chart. O-rings referenced as -136, -137, -138, -139 should all work. These sizes are 3/32" thick and range from 2" to 2 3/16" I.D.
Thickness - 3/32" (do not suggest anything thicker)
I.D. - 2" - 2 3/16"
O.D. - 2 3/16" - 2 3/8"
Preferred material - silicon, however, rubber may substitute
Thickness - 2.5 mm (do not suggest anything thicker)
I.D. - 51mm - 55 mm
O.D. - 55mm - 60 mm
Preferred material - silicon, however, rubber may substitute
DISA O-rings for the 323/328 engines have the following dimensions.This is for DISA's with the green, removable O-ring, not the orange molded seal. I also believe that the green O-ring DISA's are less problematic than the DISA's with the orange molded seal?
Again this is a BMW serviceable part, part number 11617504543.
Thickness - 1/8"
I.D. - 2"
O.D. - 2 1/4"
Preferred material - silicon, however, rubber may substitute
Thickness - 5.5 mm
I.D. - 51 mm
O.D. - 62 mm
Preferred material - silicon, however, rubber may substitute
