Very low idle. Possible vacuum leak?

[Tuskanr]

As you may know, im a new recent owner of a 1988 Corolla GT-S AE92. Now when I drive it for 20 minutes or more and have to do stop and go driving. Or am just idling for a long period of time, the idle drops to around 400 and sometimes even 350,

Now the guy I bought it from says these cars when they have vacuum leaks idle really low. Now is that true? If so, how would i go around finding it? Tips? Questions? Comments? Concerns?

Id love to fix this so i dont have to worry about it dying all the time on me.



Also one quick thing, whats a good cruising speed for these cars. Like on the freeway? 65 seems decent, but @ 70 its almost 4k rpms. and at that constant rpm's Im afraid i will heat up the oil too much.

[93corolla5speed]

I am suffering the exact opposite problem. When cold, my idle is too low; when hot, it is too high. As for your question, I think vacuum leaks tend to create a higher idle, not a lower idle. This is because the engine has another source of air from the leaking lines, and more air in the throttle body means increased throttle, and hence higher rpms.

[90 GP]

Check all the vac lines and then the plugs/ caps/ rotor/ wires/ gas filter, timing and idle speed . If you have fuel injection and have a MAP sensor ( mounted on firewall) check the vacuum line that runs from it to the manifold. Also check the EGR valve (if equipped) to be sure it isn't clogged up causing the low idle.

[Flashmn]

I'd adjust the idle a bit higher.

You wont heat up the oil too much. When I'm going, I'm doing 90 or so mph. Revs are high I know, its because the transmission is VERY short.

[freakinbox]

I've drivin 4 hours doing 140 - 160 km/h and the revs are around 4 or 5k. It's fine, like flashmn said it's because the gears are short. Even ar 100 km/h it holds 3k rpm

[Bitter]

2.5hrs at 3500 rpm (85ish mph) without any problems either. the A245E has a little longer gearing than you guys, even a sprint upto 110mph (180km/h) in 3rd and no ill effects other than a very rapid heart beat.

[Tuskanr]

Cool, thanks guys for your replies, I will check the idle screw and probabally just up it a lil bit, but I will also do all that maintenence stuff, hoses and all that, I will let everyone know how that goes.