Fuel Trim issue

[ShakesReaper]

Hi

Something on my car does not make sense. If someone can please shed some light on the matter it would be a great help to me.

I have a SURE Aeros installed. uncalibrated MAF at the moment. When doing logs to calibrate the MAF, all my long term and short term trims are in the negative. ltft like -7% and stft hovers, but sometimes at -5% and other times at -20%, considering the rpm range.

So here is my question: Why would a SRI that supposedly lets more air flow, cause my engine to pull fuel because of less air? Shouldn't my trims be positive due to the SRI?

Please advise

[Kevin]

This has been apparent even if the trims are settled. Originally we thougt that it was a leak but with a quick OL run the actual AFR > commanded AFR, so that ruled out an air leak.

[mituc]

Post a log. Maybe you have a boost leak or maybe the fuel trims are not settled yet. Drive your car for at least 200km in mixed conditions after each reflash or ECU reset when you're working on your MAF cal and then look at the long term fuel trims and leave the short time FT just as a reference.

[ShakesReaper]

I will post some logs as soon as I get them done. I did reset my ecu a couple of times and each time to do a MAF cal, but each time (after extensive driving) the LTFT settle to deep into the negatives.

[mrQQ]

I have negatives aswell. Boost leak does not explain idle negatives.

[skiptownmcat]

Vac leak maybe, check the tip to turbo connection.

[mrQQ]

vac leak would be positives.

[mituc]

At idle I guess that you will get positive trims no matter where the leak is (post or pre-turbo) because there's vacuum everywhere.

If your MAF sensor is not dirty and the primary oxygen sensor is not unseated then... I don't know...

Post this kind of questions on MSF... there are a lot of guys there that have seen the complete compilation of weird shit that can happen with these engines.

[skiptownmcat]

vac leak would be positives.

Of course, brain fart on my account!!