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Discussion Starter · #1 ·
Okey so my 320ci is running lean according to my cheap obd2 reader, both banks around 10-18%, MAF readings on warm idle is like 2.4 g/s so im suspecting that, ive replaced all rubberboots to the intake so shouldnt be a vacuum leak. I can barely get the car rolling without revving the car.
  • Replaced CCV including O2 pilot mod
  • Cleaned throttle body
  • Cleaned Idle air control valve
  • replaced all intake boots
  • Replaced air filter
  • Replaced Fuel filter
  • Replaced both camshaft sensors
  • Replaced crankshaft sensor
  • Replaced valve cover gasket
  • Rebuilt VANOS
  • Replaced 1 precat o2 sensor
I feel like it must be a bad MAF sensor with those low readings but before i order a new one i will just check what everyone else thinks.

no lean codes btw
 

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according to that post "Yes, less than 3.9g/s at idle is a good indicator of laziness, "
Think about it for a second. The typical MAF sensor value will be different for other sized engines: smaller engine, lower value.

You need to do a smoke test to find the vacuum leaks. Go follow that smoke test thread and report back what you find and have fixed.
 

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Discussion Starter · #5 ·
Think about it for a second. The typical MAF sensor value will be different for other sized engines: smaller engine, lower value.

You need to do a smoke test to find the vacuum leaks. Go follow that smoke test thread and report back what you find and have fixed.
Okey i know i smoketested it for this same problem last year trying to fix this but found 0 leaks then, i now tried pluggin the brakebooster hoose but it didnt improve the trims, I know the SAP vacuum hoose is a bit cracked so you think it could be that?
 

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Okey i know i smoketested it for this same problem last year trying to fix this but found 0 leaks then, i now tried pluggin the brakebooster hoose but it didnt improve the trims, I know the SAP vacuum hoose is a bit cracked so you think it could be that?
It could be many things. Smoke test it to find the leaks!

Know that the SAP vacuum line has an electric valve that only opens when SAP runs at cold starts. Get a mirror and bright light behind the IM and inspect where it connects to the vacuum port, maybe one of the caps is missing?

Smoke test it to find the leaks!
 

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Discussion Starter · #7 ·
It could be many things. Smoke test it to find the leaks!

Know that the SAP vacuum line has an electric valve that only opens when SAP runs at cold starts. Get a mirror and bright light behind the IM and inspect where it connects to the vacuum port, maybe one of the caps is missing?

Smoke test it to find the leaks!
Okey i hear you and i will try to smoketest it again but another reason i dont think it is a vacuumleak is that when i rev it up to 3k rpms the fueltrims still say lean
 

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Okey i hear you and i will try to smoketest it again but another reason i dont think it is a vacuumleak is that when i rev it up to 3k rpms the fueltrims still say lean
You know, there can be multiple problems at the same time. You may have vacuum leaks AND other problems.
What is the fuel pressure in PSI at idle as well as 3k RPM?
Oh, and smoke test it to find the leaks!
 

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Discussion Starter · #9 ·
You know, there can multiple problems at the same time. You may have vacuum leaks AND other problems.
What is the fuel pressure in PSI at idle as well as 3k RPM?
Oh, and smoke test it to find the leaks!
Okey i think i found the problem, at the back of the intake manifold there are ports with brittled caps and the SAP line is bad aswell, now what do you recommend me to do? Try to change them with the manifold mounted or removing the manifold?
 

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Okey i think i found the problem, at the back of the intake manifold there are ports with brittled caps and the SAP line is bad aswell, now what do you recommend me to do? Try to change them with the manifold mounted or removing the manifold?
You can get them with the manifold in
 

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the disa valve seems bad aswell, the flap turns without resistance and doesnt spring back
There is always something to fix/replace on these old cars.
This maintenance schedule is a helpful reference.
 

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Discussion Starter · #17 ·
There is always something to fix/replace on these old cars.
This maintenance schedule is a helpful reference.
Indeed it is, thanks for the help Bali 🙂
 

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Discussion Starter · #18 ·
I have now changed the disa valve and the fuel trims went down but they fluctuate a bit, sometimes it runs rich down to max -7 and othertimes it runs lean to max +4. Is this normal or do i still have a problem? Also i noticed smoke rising from beneath the exhaust manifold at bank 2. I dont know if its burned oil or exhaust gases leaking, i have changed the VCG.
 

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I have now changed the disa valve and the fuel trims went down but they fluctuate a bit, sometimes it runs rich down to max -7 and othertimes it runs lean to max +4. Is this normal or do i still have a problem? Also i noticed smoke rising from beneath the exhaust manifold at bank 2. I dont know if its burned oil or exhaust gases leaking, i have changed the VCG.
Might just be residual oil, you'd be able to hear an exhaust leak if you had one. Could be a lazy O2 sensor?
 
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