LS2 stumbles/hesitates only when COLD.
01-30-2010, 10:00 PM
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Join Date: Apr 2002
Location: Salisbury, NC
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LS2 stumbles/hesitates only when COLD. Not sure if this is the right place to post this....
I have a 2005 GTO with 37K miles that is bone stock except for electric exhaust cutouts.
A few months ago it started stumbling a bit within the first few minutes of starting cold.
If I go out in the AM and start the car and tap the throttle for just a 1/4 - 1/2 second and then release the throttle, the car stumbles, hits 1500 RPM or so, and then drops back down to idle. I should probably post a video so you'll know exactly what I am talking about. I am not sure the RPMS change until I let off the accelerator, like something is moving too slowly.
Once the car warms up for maybe two minutes, it runs perfectly fine. Power is fine, idle is fine, everything is great.
There have never been any codes set on the car.
I removed a K&N intake and replaced it with a factory air box since this has started and it did not help at all.
I have replaced the spark plugs, cleaned the throttle body and the MAF, and nothing has helped.
I ran a Superchips tune on the car since I bought it ~3 years ago. I removed the tune about a week ago, reverted to the stock tune and it still has the problem. I removed the battery for a few hours and reconnected it with no changes noticed.
Any ideas?
This may be unrelated, although I hope it is completely related-
Since removing the Superchips tune, and when the car is cold, if I am driving and the car goes to change gears, the transmission drops out of first, the RPMS drop like mad, and then 1/4-1/2 second later the car changes to second and the RPMs come back. ONLY when it is COLD COLD. It's like the PCM is retarding the snot out of the spark when it is changing gears. This was completely unnoticeable with the Superchips tune.
Tranny fluid looks and smells like new and always has been full.
I would really appreciate any help. If someone wants a video, I'll be glad to post it once it warms up here a bit.
Thanx,
Ron
I have a 2005 GTO with 37K miles that is bone stock except for electric exhaust cutouts.
A few months ago it started stumbling a bit within the first few minutes of starting cold.
If I go out in the AM and start the car and tap the throttle for just a 1/4 - 1/2 second and then release the throttle, the car stumbles, hits 1500 RPM or so, and then drops back down to idle. I should probably post a video so you'll know exactly what I am talking about. I am not sure the RPMS change until I let off the accelerator, like something is moving too slowly.
Once the car warms up for maybe two minutes, it runs perfectly fine. Power is fine, idle is fine, everything is great.
There have never been any codes set on the car.
I removed a K&N intake and replaced it with a factory air box since this has started and it did not help at all.
I have replaced the spark plugs, cleaned the throttle body and the MAF, and nothing has helped.
I ran a Superchips tune on the car since I bought it ~3 years ago. I removed the tune about a week ago, reverted to the stock tune and it still has the problem. I removed the battery for a few hours and reconnected it with no changes noticed.
Any ideas?
This may be unrelated, although I hope it is completely related-
Since removing the Superchips tune, and when the car is cold, if I am driving and the car goes to change gears, the transmission drops out of first, the RPMS drop like mad, and then 1/4-1/2 second later the car changes to second and the RPMs come back. ONLY when it is COLD COLD. It's like the PCM is retarding the snot out of the spark when it is changing gears. This was completely unnoticeable with the Superchips tune.
Tranny fluid looks and smells like new and always has been full.
I would really appreciate any help. If someone wants a video, I'll be glad to post it once it warms up here a bit.
Thanx,
Ron
02-01-2010, 04:30 PM
#2
Why don't you take the car to a good tuner? Nick Williams is in your neck of the woods. http://www.williamsperformance.net/
