Tune was just working... Now runs rich
 

Hey guys.. I have a 93 gt2860rs on very low boost stock injectors on MSPNP. Boost gauge reads about 8 psi. Tune was fine and afr was just fine... Now it shows that I idle at 9.7-10.1. Driving shows 13.5-14.5. Once I get into boost afr shows 12-12.7... But at the same time it jerks or sounds like it miss fires... So I re calibrated my lc-1 and still shows it running rich... What else should I check for?

I was getting ready to upgrade my whole fuel system until this came about...

How tight are you plugs gapped to ? Try like .028".

How old is your ignition system ?

It needs to be pretty lean to start missfiring, and by the time you feel it you've already done damage.

It's gapped at .030... Engine has 65k on it so the coils and ignitor should be around the same mileage I'm guessing...

See the weird thing is it pulls hard and strong through first and any gear after that its rough

Did you make any mods before it started running rich?

Where is your IAT sensor located?

All I did was change the turbo gasket and change the clutch... Do you think it's a ground problem? I change out the battery and now it idles at 10.9-11.2... Which I thought was weird...

IAT is located about 8 inches away from the throttle body...

A ground problem is not impossible. I had been wondering if the IAT wasn't getting a good reading. Note that if you're still accidentally on the "with AFM" firmware, the tune will be off when the weather changes because it's not properly measuring the air temperature.

I did check that... I will double check that again... How would I test the IAT to see if it's no good?