Computer Diagnostics and Tuning Technical discussion on diagnostics and programming of the F-body computers

Negative Fuel Trim

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Old 02-01-2010, 01:12 AM
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Negative Fuel Trim

Using my autoxray scan tool, I have noticed that my bank 1 long term fuel trim at idle is usually at -11% while bank 2 long term is usually at 0 or -2.4%. My main concern is bank 1 and the reason for the negative fuel trim. The maf is clean, the injectors are flow matched and brand new, no exhaust leaks, I don't notice any misfires, and I can't think of anything else. Please help. Even if this is not detrimental, I would like to know how to correct this problem. I gotta find out what is wrong. What would be the best way to determine if the vehicle is misfiring? Could my valves be too tight on that side? Please help! Also, my o2's switch from high to low indicating that they are working. They are fairly new.

Last edited by RallyBoy1; 02-01-2010 at 01:26 AM.
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Old 02-01-2010, 03:52 AM
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Just to eliminate the possibility, have you switched the 02 sensors from bank to bank?
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Old 02-01-2010, 07:48 AM
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No, I have not switched the o2's from bank to bank. Is there anything else to look for?
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Old 02-01-2010, 10:09 AM
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Originally Posted by RallyBoy1
No, I have not switched the o2's from bank to bank. Is there anything else to look for?
just noticed that you have a bigger cam. Have you closed off your blades at idle to force all the air through the "idle air plenum"?

When cams are big and the idle air is not enough, people crack the blades to get enough air. Bad. You must do the "TB drill mod" to get the idle air correct.
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