Hi,
I have posted some prior posts on my bmw x3 in the past where I dealt with and solved issues with a no start situation. I live in northern wisconsin 10 feet from a large iced lake. It was 40 below and it just about froze the oil and I burned the ECU out trying to start it. Replaced starter, battery, then ecu and it came back to life.
After that I had rough idle problems but an otherwise smooth sounding engine while driving. Ended up being lower air intake boot causing shakey idle.
Next issue, a leak in the cooling system , was the expansion tank. Fixed and remedied.
Newest issue. Girlfriend hit a deer , caused mostly body damage to bumper, skid plate, radiator hose. All repaired but there was a period of it running hot. After this, ended up with misfires in cylinder 3. Replaced coil and plug, fixed. Another new misfire, Cylinder 4. switched coils, issue followed coil. replaced coil and it helped, but did not solve everything. THe car still has a rough sound almost like a hole in the exhaust and a definite lack of power.
I replaced all spark plugs with OEM NGK platinum. No change. Now to my actual question. Eventually it started throwing a code for 02 sensors post cat bank 2. First, can bad 02 sensors cause this crappy sound and loss of power due to incorrect trim? Is that even possible? I am skeptical since I unplugged the sensors one at a time and there was no change in noise. These are fairly easy to replace but bosch sensors are expensive for me at the moment.
My other suspicions are that there is some other air intake leak, but I checked my intakes and since I just had the intakes serviced it also seems unlikely. I visually inspected and things seem to be all connected.
Other suspicion is that the oreilly brand ignition coils are shit and that I should replace all coils with bosch and see if that helps. Also kind of expensive though.
Finally, I know that my valve cover gasket has some leaks, but not into the spark plug holes, just in the rear that causes a little to drip down by the exhaust. I visually inspected spark plug holes and they are clean. Im going to replace it anyway since it is so cheap to fix but I dont THINK this is having an affect since it was like that since I bought it.
Anyway, Im on a real tight budget but the car runs like shit. After all this im starting to have my faith in M54s and BMW in general since half the time I drive my dads 97 tahoe around while I work on this BMW which runs just fine for the last 20 years....
Would really appreciate any help anyone could offer on this as Its my primary transportation and IM trying not to "throw parts" at it.
I have also been dealing with the 4x4 light being stuck on and putting car into limp mode. Replaced yaw sensors and I know all my sensors are functioning properly but I cannot rest the light. My transfer case fluid was low causing clicking in the rear wheels, but I replaced the transfer case fluid and it fixed the problem. I am not sure if I need to computer reset transmission or something similar to get that light off, but clearing codes for steering angle sensor and other DSC not working...
Thanks
Last edited by tommymulligan; 04-11-2017 at 10:41 AM.
I have read in many places that one ignition coil going bad likely means another can be bad and not necessarily throw a code. WHen I replaced the ignition coil, it defintely affected the shake and sound on the car. I have decided to replace all ignition coils with bosch coils as a step 1.
Replaced all coils, slightly better running but problem is not solved. Engine loud and lack of power. I believe the problem is the pre cat sensor bank 2, so I will replace and respond when I have installed new 02 sensor.
Last edited by tommymulligan; 04-13-2017 at 09:49 PM.
Tested for vacuum leaks in fuel injectors / DESA Valve / intake Boots and other obvious vacuum lines. Going to do a DIY smoke test to be sure, but seemingly the conclusion that the 02 Bank 2 sensor is bad is still a possibility. Anyone got any ideas if the 02 sensor is bad? I guess the only remaining culprit is fuel delivery?
One thing I would suspect, since you say the exhaust sounds louder, is a vacuum line that runs from a canister just under the starter, to a vacuum actuator on the exhaust. Maybe this vacuum line got broken with the deer incident which would not only cause the exhaust to be louder, but would trigger CEL codes as well. You can see the vacuum line on this diagram.
http://www.realoem.com/bmw/enUS/show...diagId=18_0552
Good Luck...
Current Garage:
91 e34 M5 - spoiled & demanding 27 y/o -glanzshwarz
91 850i/6 -another spoiled & demanding 27 y/o- schwarz-gone but never forgotten
06 325i - undeserving, spoiled & demanding 27 y/o daughter's DD-hellrot
03 MINI Cooper S JCW -spoiled & demanding, yet deserving wife's DD - Chili/Panther
05 X3 3.0i -family workhorse - diamond schwarz
12 X5 3.5d - torque monster - space gray metallic
86 GMC Cabellero - Old Faithful 32 y/o DD BMW Support Vehicle
08 Cub Cadet 19HP 46" hydrostatic- yard vehicle
88 Schwinn Sierra - 1WD Off Road Vehicle
e31 & OHC BMW CCA #385540
Thanks for the reply, Im going to go check it out right now. The 02 sensor changed nothing, so I am guessing it was a byproduct rather than a cause. Im beginning to wonder just what is happening since I did the carb cleaner test for leaks on the main intake areas and found none, as well as the vehicle having been serviced for an intake leak a year ago. I suppose I could try bank 1 o2 sensor since bank 2 was pretty fouled up but sneaking suspicion its something else!
I was unable to locate the hoses but I am noticing that my valve cover gasket leak is pretty bad. there is oil both in the front and sides and rear. Could this cause enough of a vacuum leak to disrupt engine performance? I think im going to replace it either way but was wondering if this was even a possibility
I also examined the exhaust butterfly valve at the rear of the tailpipe. Its open when the car is off, and closes when the car is running. I pushed it open with the car running, and noise becomes louder so I assume its suppose to remain close when running.
The louse noise I have is very "exhausty" and increases in loudness and frequency when gas is applied. I suppose a downpipe or something could have been kocked loose from the accident as well.
Last edited by 91e34M5; 04-21-2017 at 09:48 AM.
Current Garage:
91 e34 M5 - spoiled & demanding 27 y/o -glanzshwarz
91 850i/6 -another spoiled & demanding 27 y/o- schwarz-gone but never forgotten
06 325i - undeserving, spoiled & demanding 27 y/o daughter's DD-hellrot
03 MINI Cooper S JCW -spoiled & demanding, yet deserving wife's DD - Chili/Panther
05 X3 3.0i -family workhorse - diamond schwarz
12 X5 3.5d - torque monster - space gray metallic
86 GMC Cabellero - Old Faithful 32 y/o DD BMW Support Vehicle
08 Cub Cadet 19HP 46" hydrostatic- yard vehicle
88 Schwinn Sierra - 1WD Off Road Vehicle
e31 & OHC BMW CCA #385540
My codes seem have included 02 sensors generally in bank 2 and I did have an occasional DMTL code for leakage. I dont think the DMTL pump could cause my symptoms, but I guess I cant be sure.
The symptoms began with a misfire which showed up as codes, and went away when I put in new ignition coils. The car was loud and had a light shake. The new ignotion coild resolved the shake and increased the frequency of the noise.
at that same time, I also replaced a fuel injector, but I have confirmed the seals are good with a carb cleaner test and by removing each ignition coul one by one with the car running to confirm they are all firing.
Most of the exhaust seems to be fine unless a gasket has brittled out from the exhaust manifold. A great mystery if Ive ever seen one. I going to try and post a video of the noise.
I crawled under again to feel for leaks and found a massive exhaust leak. Must have occurred from Wisconsin road salt! Explains how sudden it was. No if someone could tell me it was still a good idea to replace all ignition coils when 2 go bad and that it's good to install new 02 sensor at 155k so I don't feel like an ass spending $200 when my exhaust is the problem!
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