My friend has an 87 Trans Am with the carbureted motor, I think lg4. When she shuts it off it keeps going real rough, I was told that it was pre-ignition. A mechanic gave me a can of internal engine cleaner to help it and after I did it the car does it even worse. Now I have searched all over and I can't find on this site or anywhere some things that can be done to figure out the problem or fix it. Right now I told her just to shut the car off in drive to stall it, but I would like to fix it. So if anyone knows anywhere there is some good info on it let me know. Thanks

-Sean

 

check your tune up, make sure it's good and the carb and timing are adjusted correctly

 

yes, make sure the timing isn't wayyy too far advanced.

pre-ignition will do that though. Try using a bit of water, through a vacuum line, keep revving the motor to keep it from dying, but give it a few ounces of water (slowly) through the vacuum lines. That internal engine cleaner does about the same thing....