99 3.1L -> misfire and engine shaking

[RamJetMax]

I have a 99 Malibu with the 3.1L V6. A few weeks ago the check engine light came on the same time as the engine started shuttering. I went to Autozone and they pulled the code that it was a cylinder 1 misfire. But, as soon as they cleared the code, the engine was fine again.

How does that happen? Why would clearing the code get rid of the shuddering?

Then again yesterday the check engine light came on and the shuddering is back. I want to replace the spark plug wires and maybe the spark plug but it is in a difficult spot to reach. I don't have a jack or jack stands...is this still a DIY job or do I need to take it to my local garage?

Thanks in advance,

Drü

[RalphT]

Clearing the codes also clears the learn feature of the memory in the computer. Soundls like you have a lean condition, possibly clogged filter and injectors. Changing the plugs, wires and serpetine belt at this stage would be a good idea as well.

[bcopeland]

You might also want to replace your gas cap as well. Sometimes that has been known to contribute.

[RamJetMax]

Originally Posted by RalphT

Clearing the codes also clears the learn feature of the memory in the computer. Soundls like you have a lean condition, possibly clogged filter and injectors. Changing the plugs, wires and serpetine belt at this stage would be a good idea as well.

Thank you for your input; I will have that done.

Originally Posted by bcopeland

You might also want to replace your gas cap as well. Sometimes that has been known to contribute.

I am curious, how would a gas cap contribute to the engine running lean or having misfire issues.

[bcopeland]

With the emissions system tightly closed. I have had two gas caps render trouble codes. Once with the shuddering and hesitation. It really caught me off guard. I had the codes checked and was told emmisions etc. but I further inquired and was told that sometimes the gas cap does that. Replaced it and wallah!

[jeddi20]

i talked to my friend who is a cadillac mechanic, he said that it sounds like the timing could have jumped. you need the to get the timing reprogramed. the only way to do it is either A.) go to the dealer and have them do it or B.) find someone with a TEC-2 scanner. i have a friend that has the same problem with his 00 malibu.

[bearcatdon]

The infamous intake gasket can cause an intermittent cyl. misfire code. Check for coolant leaks on the LH side of the block. Look at your coolant to ensure you don't have oil in it.

[dddellinger]

Did you ever find the source of your problem? I have a 3.4l that has a very similar problem with misfires on cylinder #1. Coil, ignition module, plugs and wires did not fix the problem.
Using a Tech 2 scanner seemed to indicate that the cam position and crank position sensors were all OK, too.
Thanks.