Help! Lean codes and idle stalling issues

J

JP701

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Nov 18, 2024
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Hi All,

I have a U.K. Z3 2001 2.2i M54 engine.

I’ve had for a long time lean codes (both banks) popping up on random occasions for a few years now. Some things were done including, smoke test/CCV change/O2 sensors checked/Fuel pressure check/MAF sensor checked.
Recently been having issues with starting (taking a while to crank) and low idle stalling and jerky throttle control. Occasional throw up of the camshaft sensor fault but I’m getting confused if all this is still caused by the initial lean symptom.
I can send a video of me revving the engine from idle to a little over 1000rpm. Sometimes it will drop to a lower rpm pushing the throttle and sometimes as it falls back to idle it dips below and can stall.
Any info or suggestions hugely appreciated!
 
Do you think that’s been the cause of my previous lean codes though?
Thank you for your response
 
The symptoms you describe, in addition to the camshaft sensor fault, seem to indicate such.
 
JP701 said:
Can I send you a video of the engine running? Is that possible on here..?
[/QUOTE

You can't upload video directly to this forum. You need to upload it on YouTube (or similar) then post a link to the YouTube video on here.

Tony.
Click to expand...
 
Long crank is certainly a symptom of a bad camshaft sensor, as you have already seen a code for this best replace it with an oem sensor do not use cheap pattern parts.
 
colb said:
Long crank is certainly a symptom of a bad camshaft sensor, as you have already seen a code for this best replace it with an oem sensor do not use cheap pattern parts.
Click to expand...
Thank you for the reply! I’m gonna replace the sensor hopefully. And I’m just confused still whether it will solve the lean problem or has it been the lean condition causing the sensor/computer to make that sensor faulty..
 
Hi All,
Some work was done on my Z3 replacing the camshaft sensor with a Delphi one and its fixed the stalling issue but the Lean code Bank 1 came on again the other day so the lean issue still exists sadly. One to thing to note is car is taking a little longer to crank start than usual. I’m at a lost cause where to spend more money and time into this situation. Financially screwing me over to say the least.

Any help from anyone is hugely appreciated 🙏
 
One thing to note is that the Long Term Fuel Trims seem to be a bit on the high side ~14%… not sure if disconnecting the battery does a factory adaptations reset on the ECU or not…. Any thoughts?
 
Camshaft sensor replacement has obviously helped but high fuel trims remaining would lead me to believe its getting unmetered air in which is fooling the exhaust sensors into thinking its running lean, hence adding fuel to richen it up. Will do that up to 20% before it gives up and sets the EML and codes. I know you smoke tested it already but worth repeating and also viewing the exhaust sensors in live data to see what they are doing. Misreporting Maf is also a possibility no real way of checking that other than seeing what its doing under throttle in live data. When looking for air leaks be sure to check all rubber and plastic vacuum pipes and boots across the engine. Also check the underside rear edge of the inlet manifold for any missing or split rubber blanking caps which are often overlooked. Dipstick tube O ring can also be suspect. Cam cover gasket must also be intact, no oil leaks, if they leak oil they also let unmetered air in.
 
Does your engine have a secondary air pump? If so, Look for broken rubber hoses and stuck open valves there. An exhaust leak, SAP leak at or before the pre-cat O2's will show as a vacuum leak. One that an inlet manifold smoke test can not find.
 
Let it run in idle and spray carb cleaner all around the hoses and possible leak points. Most of the times they reveal their problem this way.
 
Thank you all for your help and the z3 knowledge here is awesome. I’m not aware of a secondary air pump however I can ask my local mechanic. At the moment it seems to be only bank 1 giving me grief and this usually happens once warm and at low (1500rpm) revs, cruising at 40 mph and there’s a slight delay in the start crank before she fires up to life.
More investigation needed, but I’ll try all the points you’ve mentioned guys thank you!!
 
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