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Discussion Starter · #1 · (Edited)
Looking for some thoughts on my persistently negative fuel trims (-12 idle, -7 cruise). I did the intake, UICP and FMIC installs myself and had the TBE done at Mitsu dealer. Any ideas on why it keeps creeping so negative? My first thought is an air leak somewhere in the intake system after the MAF sensor, but haven't found one. Is this somewhat expected when using an OTS map that is intended for a slightly different intake? The Cobb SF is the map most people seem to be using with the ETS intake as they're most similar. Also, not sure if this might be related but I've had some boost spikes up to 28psi on this tune and am switching to the LWG map to address this until my 3-port and custom E-tune. Any ideas would be most appreciated. Thanks.
 

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An aftermarket intake will likely affect the fuel trims as it's usually a bigger diameter compared to stock.
I see from your signature you are running Cobb AP, stage 2. Likely the MAF scaling for this map is not optimal for your setup. Check if your tuner can do a customize tune for your car.
 

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Discussion Starter · #3 ·
Hey, thanks for the reply. Just spoke with Cobb and he basically said the MAF will be way off cause the ETS intake is way bigger than the Cobb SF, which would explain the negative fuel trims as well as the over boost. Weird as many people claimed that the Cobb SF was a good substitute for the ETS intake... guess not. Will try AMS Stg 1 and go from there until I get my custom tune. Thanks again.
 

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Discussion Starter · #5 ·
Didn't know I could! I'll look into it for sure. Thanks man.:godance:
 

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Why not just do a MAF cal? It pretty simple. Just need about 30 minutes of logging time then use the calculated I have developed to update the map.
Didn't know I could! I'll look into it for sure. Thanks man.:godance:
You don't even need that really, you can get XYZ company scaling for free. ;)
 
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