Multiplicative vs. additive fuel trim lean DTCs
#1
AudiWorld Senior Member
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OK.
I looked through the archives, and there seem to be some of each of these DTCs thrown. The universal answer is MAF, and when that doesn't fix it, MAF again.
The Bentley says that the additive is at idle only, while the multiplicative is at all engine speeds.
Does anyone actually know what DIFFERENT failures cause each code - Or should I just join the mob mentality and chant "MAF Must Die, MAF is Evil, MAF Must Die, MAF is Evil..."?
I looked through the archives, and there seem to be some of each of these DTCs thrown. The universal answer is MAF, and when that doesn't fix it, MAF again.
The Bentley says that the additive is at idle only, while the multiplicative is at all engine speeds.
Does anyone actually know what DIFFERENT failures cause each code - Or should I just join the mob mentality and chant "MAF Must Die, MAF is Evil, MAF Must Die, MAF is Evil..."?
#3
AudiWorld Senior Member
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Is what I'm getting.
Only 1 bank. Seems like most people with MAF problems had both banks multiplicative:
17536 - Fuel Trim: Bank 1 (Mult): System too lean
35-00 --
17538 - Fuel Trim: Bank 2 (Mult): System too lean
35-00 --
I do NOT have these (Yet?)
So I'm thinking 02 sensor or plumbing. Plumbing would probably come into play off-idle in my past experience, so what is messing me up at idle I wonder.
Only 1 bank. Seems like most people with MAF problems had both banks multiplicative:
17536 - Fuel Trim: Bank 1 (Mult): System too lean
35-00 --
17538 - Fuel Trim: Bank 2 (Mult): System too lean
35-00 --
I do NOT have these (Yet?)
So I'm thinking 02 sensor or plumbing. Plumbing would probably come into play off-idle in my past experience, so what is messing me up at idle I wonder.
#4
AudiWorld Super User
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I would agree that since it isn't both banks it probably isn't the MAF, I had lean error codes (I can't remember which and it turned out to be a bad pressure release valve somewhere before the turbos (hence no boost pressure yet)it was replaced under warranty.
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