Hey everyone, I've been having an interesting problem for the last couple of weeks. I was wondering if anyone could give me an insight into it. When sitting in traffic in drive, the car sometimes(about 1 out of every 3 or 4 drives) starts bumping a little bit. The tach dips a little bit and the car shakes. There doesn't seem to be any pattern to the bumping but once it starts it doesn't stop until I leave the stop light. If I put the car into Neutral or Park the bumping will stop(possibly due to the decreased load?). I don't seem to have any problems with the car when it's not idling and it drives fine. A month/month and a half ago I got a rear bank O2 code, and I just ordered all new o2 sensors(since I just topped 100k anyways). If the O2 sensors don't fix the problem I will probably take it to a mechanic to have it looked at. The rear bank doesn't affect fuel/air ratios anyways, so I don't think this is the problem(but maybe). Anyone else have this same problem/know what's goin on? Also, I always use premium, and just got new spark plugs about 5 or 6 months ago.

Thanks,
Erik

 

It's a cheap fix and it cured my idling problems even though they weren't the same as yours it will only cost you a can of throttle body cleaner.... Clean throttle body & more importantly clean IAC valve, how to's in the stickies, hope this helps

 

You have a 99 which is prone to coil pack failures that cause misfires. My 99 makes that same every so often bump, but otherwise runs perfect. I've had a coil pack completely fail on me resulting in a 5 cylinder engine for a day, not fun.

If your bump is excessive and annoys you, I suggest replacing all your coil packs. It's a bit expensive but the advantages of a smooth motor and more power from a good spark is worth the cost. You can find deals on used coils on Ebay or check the org for deals on a new set.

 

Going to give that a try, hopefully it works.. I have the same issue as the thread starter