Quote:
Originally Posted by Vtx531
I checked vacuum from the brake booster hose. It was slowly waving up and down between 17.5-18”. Is that acceptable? I did another smoke test and couldn’t find anything.
I unplugged the MAF, didn’t drive it but just revved in the driveway. Seemed to improve but still showing lean condition (you add the numbers together correct?) When revved to 4,000 rpm:
Stft1 -14.84%
Stft2 -16.41%
Ltft1 +31.25%
Ltft2 +31.25%
I removed the MAF and it is a Bosch unit. Looks to be in good shape visually. Not sure how to tell if it is genuine Porsche part or aftermarket Bosch. .00 end of part number so it is not the newest version .01.
I took MAF readings at various rpms and it is a straight line when graphed.
800 4.25 g/s
1400 6.00
2200 9.5
3000 12
Where do I go from here??
Would an exhaust leak affect both banks?
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Your vacuum reading is right at the low end of the range but acceptable.
I would unplug the MAF and then take it for a drive to see if it performs differently.
Your long term fuel trims are learned trims based on your short term trims.
So if you have an issue such as a lean condition and then you fix it. It takes some time for the ECU-DME to begin to adjust (Learn the fixed fuel trim) and show as a more normal long term fuel trim.
Going on memory from research here but yes you add the trim numbers together. Bank 1 short and long term added together should not exceed 10 if I remember correctly. same for bank 2.
No an exhaust leak would not affect both banks as the Porsche has twin exhaust manifolds. Sorry brain fart on my part.
Going back through your posts if I read them right you had high positive (no plus or minus sign so I am assuming plus) short term fuel trims before you unplugged the MAF
After you unplugged the MAF you had high negative short term fuel trims. So in my head (oh god) your issue could be MAF sensor.
Unplug it take for a drive see if you still have the hesitation.
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