Fuel Trims Pegged at Idle ?
Thread Starter
Burning Brakes
Joined: Mar 2001
Posts: 1,228
Likes: 17
From: Mansfield Texas
Fuel Trims Pegged at Idle ?
99 C5 VERT 6SPD with a 418 Stroker that was professional tuned by LG Motorsports and dynoed 475 RWHP and Torque. Open loop at WOT is no problem. I'm running 42 lb SVO injectors (green top).
I'm having issues with the fuel trims at idle and part throttle especially under 2,000 RPM under cruising street conditions. It seems according to their scantool that I'm not getting proper voltage at the IAT Or MAF at an idle. No PCM codes or check engine light just an erratic idle that seems to fluctuate 150-200 RPM at idle. Any ideas? Could it be a bad PCM? I have cleaned and secured all ground points on the motor and chassis.
I'm having issues with the fuel trims at idle and part throttle especially under 2,000 RPM under cruising street conditions. It seems according to their scantool that I'm not getting proper voltage at the IAT Or MAF at an idle. No PCM codes or check engine light just an erratic idle that seems to fluctuate 150-200 RPM at idle. Any ideas? Could it be a bad PCM? I have cleaned and secured all ground points on the motor and chassis.
Safety Car
Joined: Sep 2003
Posts: 3,558
Likes: 2
From: Cape Coral FL
Tough to say. Did this happen after the tune? Who's scanner showed the problem?
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I had this problem after I retuned my VE table using a WBO2. Everything looked fine until idle. Then the LTFT's would go to +20. This was even after I re-cal'ed my MAF using a WBO2. As it turned out the method to recal an MAF using a WBO2 was a little off. I had to apply a mathematical function to it in the lower cells around the idle. I had to bring them up quite a bit. I learned that the MAF has a big impact on idle mixture. I have a stock bottom end but I'm wondering if this is happening with your motor...
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I had this problem after I retuned my VE table using a WBO2. Everything looked fine until idle. Then the LTFT's would go to +20. This was even after I re-cal'ed my MAF using a WBO2. As it turned out the method to recal an MAF using a WBO2 was a little off. I had to apply a mathematical function to it in the lower cells around the idle. I had to bring them up quite a bit. I learned that the MAF has a big impact on idle mixture. I have a stock bottom end but I'm wondering if this is happening with your motor...
