Engine Miss - EGR Valve problem??

[jim-milwaukee]

2005 Impala. 3.4L. When first take-off from a stop, and accelerate slowly, the engine feels like it misses a lot. Misses bad. feels like the car will stop and die. Especially on the shift change from 1st to 2nd. Misses only happens when engine is up to temp, and only on a slow take-off. When engine is cold, problem not apparant and when I get on a highway ramp and am accelerating fast, no problems.

No check engine light. Ran a diagnostic - no codes.

If I unplug the EGR, the problem goes away. I replaced the EGR, so this is not the issue.

Anyone know what electronic signals feed into the EGR that signal it to open/close?

[stuzman]

Originally Posted by jim-milwaukee

2005 Impala. 3.4L. When first take-off from a stop, and accelerate slowly, the engine feels like it misses a lot. Misses bad. feels like the car will stop and die. Especially on the shift change from 1st to 2nd. Misses only happens when engine is up to temp, and only on a slow take-off. When engine is cold, problem not apparant and when I get on a highway ramp and am accelerating fast, no problems.

No check engine light. Ran a diagnostic - no codes.

If I unplug the EGR, the problem goes away. I replaced the EGR, so this is not the issue.

Anyone know what electronic signals feed into the EGR that signal it to open/close?

Take a look on the scanner and make sure that the commanded signal matches the actual signal back from the EGR. Also, take a look at your fuel trim(s) to see what the PCM is doing with the fuel injection. If you have negative trims at idle and then they look good at say 2500 RPM, suspect a vacuum leak.