I, too have a shimmy @ idle...

[dafirebird]

ok, so i've read a few people here have a sort of "loping" at idle. So far, i've replaced the following:

1-Spark plugs(NGK-TR55, Iridium)[gapped @ .60]

2-Wires(MSD)

3-Coils(MSD)

4-Fuel filter(AC-Delco)

5-pcv valve

BTW, It's a 2002 Firebird, 3800II, Auto Trans, 49,000 rounds.

Hasn't made one bit of difference. I've read other people have had MAF probs, but i've disconnected it and it runs 10x worse. So i plug it back in and hope that's not it. Also, I'm not sure if its related, but during slow to moderate acceleration, within the range of 1800-2100 rpm, just before it shifts into final drive, I feel a vibration; then it upshifts and feels fine. If I hold it there to keep it from upshifting, the vibration continues. I only mention that cuz i called a trans shop about the vibration and he said its probly a missfire; but i have no codes or SES light. It's not a very bad shimmy, but it's not perfectly smooth either. I would appreciate any info.


1,000 thanx Paul

[TheGreenPunisher]

You could potentially have a fouled plug....

But potentially, it could be anything....whos to know...

[dafirebird]

I'm not sure it could be a fouled plug. It ran exactly the same before, and after I changed plugs recently. I'm starting to think that's just how it runs, get used to it. I had a '99 v6 Firebird before this one, and it too had a slight shimmy in idle. I took that car to a couple of shops and both said the same thing - "nothin' wrong w/it." But it should run perfectly smooth, right?? Like you can't tell it's even running unless you check the tach.

[Red]

might run some lucas fuel system cleaner through.

[ianwells100]

clean the IAC sensor, its an easy 5 minute job.. which needs to be done every so often, anyways... see if that makes a differece

[2002 v6 camaro uncharged]

When you unplug the MAF sensor the car has to be warmed up first. When I left it unplugged the car would run horrible at a cold start and almost stall but after the car was warm it idled and ran like a champ.

[dafirebird]

ok, I'll go ahead and clean the IAC sensor, and check the MAF when warmed up - cuz when I unplugged it, it was just at start-up. Also, I've Sea Foamed it twice.

Thanx guys. I'll post my results.....

[dafirebird]

ok, I cleaned the IAC sensor - no change.
I'll unplug the MAF tonight when I get home from work. I'm doing these things one at a time so I can see a difference after each step....

[cmartin99]

could be the throttle positioning sensor

[IceBird]

Did you remove the screen in your TB? When i removed mine it developed a mild studder .