I have a fairly stock 87 Integra. Manual transmission, never had any problems with it.

Until now.

Not always, but often, when my car is at idle, it fluctuates up and down. With this, the car also overheats. The car is fine to drive minus this problem...which I think will cause more damage unless I fix it.

I was told it was the airflow meter/throttle body, and I replaced that myself, and the problem persisted. I had a coolant leak, and also fixed that. Still the problem is there.

Does anyone know what could be causing this?


Modified by Volko at 4:55 AM 10/8/2008

 

I would worry about the overheating first.

Tell us more about when it happens

 

When I first start the car, it runs fine at idle for a few minutes, then after a few minutes the idle fluctuates up and down between about 900-2000rpm. This will constantly happen until i turn the car off. This in turn, causes the car to overheat, I don't know why.

It's like the fuel injection computer system is going "alrite give it more air...no, wait, give less air...wait, give more..." and it's confused and it just keeps going up and down.

I thought it might be a vacuum leak but I have no idea...

 

Do you notice any difference while driving it?

Does the car smoke while fluctuating?

I would start with a basic tune up. Plugs, wires, cap, rotor, and fuel filter.

 

Nothing except the idle and overheat problem which are related in this case...

Driving is fine untill I stop at lights and I'm idling. The problem started months ago but would only happen for a second or two a week, I thought nothing of it. Now it happens constantly. I'll work on a few things tomorrow and see what happens, then I'll tune it.

If anyone else has any ideas feel free to help me out!

Thanks guys!

 

Drained all the oil and coolant, with flushing treatment, and refilled it with new liquid, as well as topping up everything, aswell as other minor fixes...

Problem still persists. open happens when the car is running for some time, and the coolant boils very hot. The car overheats and the idle shifts around (not as much as before).

Radiator fan doesn't start up. Going to hook them upto the ignition tomorrow so they're always running, and see if the problem persists...

Any other ideas?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Volko &raquo;</TD></TR><TR><TD CLASS="quote">Radiator fan doesn't start up.</TD></TR></TABLE>

This would do it. Do yourself a favor and hook it up to a switch inside the car.

 

Good chance your cap is bad. I've seen that cause idle problems. Also a good chance your IACV is dirty. It's on the back side of your intake manifold. It's got two little coolant hoses running into the bottom of it. Remove it and then remove the little cover on the bottom where the hoses were hooked up. Clean that off and see if that helps. As for overheating, any idea when your water pump was last changed?

 

I've hooked the radiator fan onto ignition, and the car has stayed cool and the idle has stayed low. Not sure if overheated causes the idle to fluctuate, but I'll drive it in for a bit, and see how it goes...

Once my workshop manual comes that I've ordered, I'll have a better chance to clean all the fuel injection/related things...

 

water pump works and the car still runs a little warm....

 

It still overheats a lot, and then the idle fluctuates heaps while its really hot...

Checking the thermostat housing today

does anyone have any more ideas?

 

It's your head gasket. It happened with me on my DA and now I'm replacing my motor because it kept on getting worse. Maybe you don't have to go as extreme as replacing the entire motor, but if you were thinking about a swap, maybe now is the time to do it. Ever thought about swapping in a B18C or any B18 in general?

 

Only have a few hundred to spend on the car and im trying to do most of the work at home...

I have no idea what else could be the problem. The bleed valve for the radiator was clogged and i unclogged it and removed all the air, but still no luck

car overheats and idles high...

 

Hmm. You're pretty much screwed with a few hundred because it would also be a good idea to get a valve job too. That was my mechanic's recommondation when he diagnosed my ride.

 

I've fixed a lot of other things so far, I don't know why I'd need to spend so much on money as most of the work you pay for is labour at a mechanic...