Patrick G
September 30th, 2005, 01:38 AM
This is very frustrating. I have been working on tuning my car for months and I still have one nagging problem. My car will not hold a steady cruise between 1000-1200 rpm. It will accelerate smoothly in that range and it will decel smoothly in that range, but at a steady cruise (like going through a school zone or parking lot), the car will buck and shake.
Here's what I've done to try to eliminate this problem.
MAF-less speed density tune.
Base running airflows correct at various temps.
IAC Effective area modified to allow Dynamic Air and Idle Air to match from 0-100 IAC counts.
Spark tables from idle and main tables match at lower rpm levels and loads.
Increased spark timing (32 degrees) for improved idle and low speed driveability.
Throttle cracker trimmed.
OK, here's what I think the problem is: When cruising at 1000-1200 rpm, there seems to be a conflict between the IAC motor and the PCM. I'm sure I'm getting some nasty reversion from my cam at this low rpm level, so that doesn't help either. But at a steady 4-7% TPS, the motor absolutely will not hold steady at this rpm.
Is there a way to limit the IAC from trying to correct above a certain rpm or vehicle speed? Setting the throttle follower and throttle cracker to 0 does not help.
FWIW, I am new an EFI Live newbie, but an HP Tuners veteran
Here's what I've done to try to eliminate this problem.
MAF-less speed density tune.
Base running airflows correct at various temps.
IAC Effective area modified to allow Dynamic Air and Idle Air to match from 0-100 IAC counts.
Spark tables from idle and main tables match at lower rpm levels and loads.
Increased spark timing (32 degrees) for improved idle and low speed driveability.
Throttle cracker trimmed.
OK, here's what I think the problem is: When cruising at 1000-1200 rpm, there seems to be a conflict between the IAC motor and the PCM. I'm sure I'm getting some nasty reversion from my cam at this low rpm level, so that doesn't help either. But at a steady 4-7% TPS, the motor absolutely will not hold steady at this rpm.
Is there a way to limit the IAC from trying to correct above a certain rpm or vehicle speed? Setting the throttle follower and throttle cracker to 0 does not help.
FWIW, I am new an EFI Live newbie, but an HP Tuners veteran