rough idle

[sltintexas]

I just got a 96 corolla with 168K miles that has a rough idle. It just vibrates when it drive but stopped (like at a red light)..doesn't sputter or anything...starts and runs with no problems. The plugs and air filter were recently changed, but I don't think the wires were.... any suggestions on where to start...

This was my parents old car and I know they didn't take very good care of it. I was thinking about starting here:

run seafoam through it (tank, manifold, and oil)
replace wires

what else should I do or check. The car still gets great gas mileage 28-30MPG, so I am not super motivated to spend a lot of money fixing the vibrations (they are pretty minor), but I will consider any suggestions..thanks!

[jcturbo]

replace all the motor mounts, this is a common problem on the 93-97 corolla's, they're not broken, but they're weak

[sltintexas]

cool, thanks! That explains a couple other things too!


I've replaced engine mounts in an old v8 I used to have...you know the kind that were basically a big piece of rubber with a metal place on the back...I suspect these will not be so easy... How many are there, any idea? I have seen engine mounts in other cars that are on top of the enginge that mount to the frame... are there any on top or are they all on bottom..... any DIY threads that you know of...I'm gonna do some more searches too...thanks!

[ecucio]

Have you eliminated the wheel alignment and balancing? You might want to check that if not.

[sltintexas]

Have you eliminated the wheel alignment and balancing? You might want to check that if not.

it vibrates while in drive, but stopped....

[Flashmn]

I would just skip the seafoam and buy beer with that money. I personally think seafoam is as useless as motorup, etc.
The rough idle can be engine mounts, o2 sensor failure causing an over rich/lean mix, bad plugs/wires, leaky exhaustpipe at some point. Also inline 4's arent the smoothest of engines around so might be just that.

[sltintexas]

here is my theory...feel free to shoot holes in it.... since the car is getting such good gas mileage (last tank 30mpg), I am thinking it is less likely to be something like bad wires, fuel mixture etc..... and more likely to be motor mounts.... what do y'all think..

I am hoping to spend some time this weekend taking a look at the motor mounts to see if they look weak/cracked/dying...of course there is always the fact that you say, the inline 4's aren't smooth running to begin with...

any comments....