Engine shakes at idle

Thank you found problem it was the EGR thanks for all the tips on your web site has alot of useful information I needed I didn't even know this web site excited thanks to my son.

Thanks for the help the guide to clean the throttle bore is great fixed the problem engine runs perfect now, I love this site.

Perfectly fine had no problems maybe needed a tune-up but not that bad really I dont know. Road the highway out west about 7 miles then went to the gasstation about 3 or so blocks as I turned the corner it seemed like it didnt want to go had to hold my foot dwn on the gas peddle. It want stay started out of gear if it is startd it would cut off after abou 10 minutes. There are no leaks or smells but there is a blueish white smoke that comes from the muffler

Hello all,

After unsuccessfully spending some time on Google, I have decided to venture into the forums.

I have a 1993 Pontiac Grand Prix 3.1 Liter LE with 67,200 miles (I know, my grandma's old car). My original problem was that every once in awhile the engine would start running very rough, my acceleration would decrease, and the car would shake noticeably; a strong rich smell came along with all of this. Usually, after maybe 10 or 20 miles, everything would return to normal.

My trusted mechanics suggested that I replace the computer because it was reading out with junk codes. I ordered a new computer from the dealer; when they assured me that the car would start if my friend installed it, I asked him to do so.

Unfortunately, the car now starts and then dies immediately. I am not sure where in the process it is stopping, but the whole engine shakes and you can smell the fuel. I believe this means it's cranking, but the engine won't run. Also, we put the old computer back in and it does the same thing. We did transfer the memory-chip.

I would really appreciate any ideas. My friend is a fairly knowledgeable mechanic although that is not his job; he has a lot of tools and I'm sure we could run at least some tests if you have any to suggest.

Thank you very much,
Ira in Seattle

Hi and thanks for responding so promptly.

All right, the car starts and runs now without me doing anything but turn the key. It is running really rough right now, however, and has been for 30 or 40 miles.

My friend's theory is that the computer just needed time to figure out what it needed to do (it's been about 22 hours since we reinstalled the old computer.)

His suggestion is that I drive it as normal and hopefully the computer will be reset. However, I know that my mechanics checked the codes, got a bunch that seemed like too many, reset the computer and drove it around, then scanned again and got new codes. The dealer I took it to later also scanned and got Codes 65, 12, 14, 15, 22, 23, 24, 32, 46, 66. They wrote: "cleared codes and some codes reset. Found numerous engine sensor show reading incorrectly through ecm. Recommend to repace ecm and then recheck systems."

The car had an inspection on June 14, 2012. They replaced oil filter and idle air valve, and engine looked fine.

I had a new starter put in last March.

Other repairs over the last few years I am unsure of dates:

New alternator I think in Fall of 2010, and new brakes in either late 2009 or early 2010.

I don't think they checked the stuff you are asking about; I need to swing by my parent's house and see if they have records for 2011 and before, the records I have only go back to 2012.

Thanks again.