when idling car shakes

[CodyjCA]

When i am stopped i idle at just around 8500, and every 4 sec or so it will go down to 5000 and the car kinda moves around then it goes back up and it does that over and over.
i susually give it a little gas while hilding the break, that stops if from shaking around.
i have a carb, anyone know exactly whats going on?

[jumpshotjonny]

The same things happens to me, when idling at a stoplight or something the car will shake like you said every couple of seconds, seems to do it more when the car is cold. Also, if I leave it idling in park more than a couple of minutes it starts idling high then going back down over and over again. I have an '86 Corlla carburated as well. I don't know whats going on but I'd like to find out.

[Limnos]

Idle at 8500? My car idles at 600.

I found this link to something that might help you: groups.google.com/groups?hl=en&lr=&ie=UTF-8&safe=off&threadm=Pine.BSF.3.96.981215065621.2859 B-100000%40soda.CSUA.Berkeley.EDU&rnum=3&prev=/groups%3Fq%3D81%2Bcorolla%26hl%3Den%26lr%3D%26ie%3 DUTF-8%26safe%3Doff%26selm%3DPine.BSF.3.96.981215065621 .2859B-100000%2540soda.CSUA.Berkeley.EDU%26rnum%3D3

[ctrigger]

UHHHH!!! 8500? I think u r mistaken. Maybe 500!! Because mine idles at 500 rpms then jumps to about 7-800 rpms! It started happening after i installed a CAI but mi9ne is a fuel injected 04 corolla s. It's simmered down a bit and my check engine light hasn't come back on since i re-installed my old stock filter! But, it still shakes rattles and rolls!!!! Confusing man i don't know what the deal is. I'm taking mine to the toyota dealership sometime this weekend to find out whats wrong.

[CodyjCA]

ah yea my mistake, its aroud 850, my car has never idled at 500, should i get it retimed?

[NDR008]

yes, got get it checked, could be the idle jet or something is clocked.... just go to a good carb mechanic. If it was an ECU car it could be serious, but being carb.... should be a small thing. Flashmn might give a suggestion...

[Flashmn]

If it was an ECU car it could be serious

It might be a busted o2 sensor if it was an EFI car

It shakes because the engine RPM falls down so much, what I would check is the timing, the hoses that go to the distributor cap vacuum advancer. See if those are ok. If they are, then I'd go check the throttle pot on the left side of the carb, thats what holds the throttle slightly when you release it. If its adjusted too low, the rpm would slowly creep the low level.

oh and hows the fuel filter, changed it anytime soon?

[CodyjCA]

i changed the fuel filter about 4 months ago