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Old 10-17-2011, 09:57 PM   #1
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Default 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...
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Old 10-17-2011, 10:09 PM   #2
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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.
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Old 10-17-2011, 10:17 PM   #3
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It's gapped at .030... Engine has 65k on it so the coils and ignitor should be around the same mileage I'm guessing...
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Old 10-17-2011, 10:20 PM   #4
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See the weird thing is it pulls hard and strong through first and any gear after that its rough
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Old 10-18-2011, 09:30 AM   #5
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Did you make any mods before it started running rich?

Where is your IAT sensor located?
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Old 10-21-2011, 01:34 AM   #6
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Quote:
Originally Posted by Matt Cramer View Post
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...
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Old 10-21-2011, 10:59 AM   #7
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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.
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Old 10-21-2011, 06:27 PM   #8
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I did check that... I will double check that again... How would I test the IAT to see if it's no good?
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