1987 Corolla idle surging problem

[The Phantom Miria]

It has about 175,000 miles. I forget the exact amount, but its not super important. Its a 1987 Corolla, 4ALC 1.6 liter engine.

Basically, from one stop to another, it went from running fine to surging. It will go from almost dying to about 2,000 RPM or so, then drops, then rises. It almost didn't make it home.

With the air filter off, and your hand covering the hole, it runs fine, as soon as you take it off it surges again.

So, we took the carborator off and took it completely apart and fixed gaskets and such, everything looked good. Checked the EGR valve, cleaned it, it works fine. The PVC valve, same thing. We checked all the vacuum lines, everything worked normal.

After we put it all back together, it was like nothing had been done. The surge is the exact same. If you turn the idle up a little, it runs enough to drive, but still surges. If you drop the idle, it almost dies.

So, what else could it be? My dad, whos been working on cars for 30 years, is lost. Our neighbor who went to school for cars, he has no idea what it is. And since theres no computer, theres no code to look up.

So...whats the problem?

Thanks for any help.

[rickhart]

Had a similar problem some time ago with a different car and it turned out to be contaminated fuel--probably water because adding anhydrous isopropyl alcohol fixed it. Barring that, you can try disconnecting the EGR entirely in case it is sticking in the open position.

If you don't get any more suggestions from readers, then find an experienced Toyota mechanic that was repairing your kind of car when it was new. It might not be easy to find, but if you do, they will be worth their weight in gold. Mine is one of the lead technicians at a very large Toyota dealership nearby.

Good luck !

[MyCorolla]

Originally Posted by rickhart

Had a similar problem some time ago with a different car and it turned out to be contaminated fuel--probably water because adding anhydrous isopropyl alcohol fixed it. Barring that, you can try disconnecting the EGR entirely in case it is sticking in the open position.

If you don't get any more suggestions from readers, then find an experienced Toyota mechanic that was repairing your kind of car when it was new. It might not be easy to find, but if you do, they will be worth their weight in gold. Mine is one of the lead technicians at a very large Toyota dealership nearby.

Good luck !

My Toyota had been sitting around for at least a year and a half. I would start it every few months to makes sure the battery did not die and so that the tires could be moved a bit so they did not get a flat spot.

I have that same idle problem, however mine is fine at normal temperature but when the car warms up, then the idle "heaves" faster and slower.

When I put my foot on the gas the idle increases fine. The car was almost empty so I added three gallons of unleaded supreme, I presume the old gas would have been washed out by now.

I also have replaced the fuel filter, air filter, some vacuum hose lines, and cleaned out the EGR valve and where the EGR valve connects to the engine.

[generalyen]

my 87 fx16 was doing that and it turned out that it was the idle air control valve which they wanted like 200 dollars for a new one. so i got a piece of stainless and plated it off and just manually set my idle to 1100rpm. runs like a champ.

[MyCorolla]

Originally Posted by generalyen

my 87 fx16 was doing that and it turned out that it was the idle air control valve which they wanted like 200 dollars for a new one. so i got a piece of stainless and plated it off and just manually set my idle to 1100rpm. runs like a champ.

Would a 1978 Toyota Corolla 5 speed wagon have an idle air control valve that is similar to your 87 fx16?

I really appreciate the info, thanks for posting it.

[gyp]

I have an 86 AE82 4ALC doing this at 180+ mi. I don't know anything about cars, but it sounds like, if there were 4 cylinders, then 3 of them race and the 4th sputters. Cold in the morning it would stall at the first couple of stop signs. My partner was messing with the idle speed, he had it racing so hot I brought it by a local shop, the guy showed me 'moisture inside the carburetor' (I looked but I wouldn't know what a dry one looked like), he said it's probably old and leaky, get another from the junkyard to try. I'm wondering if it sucks moisture from the air and tries to burn that. It does run smooth-er when warm, but if I sit and idle it is irregular, it will still choke on something sometimes, the headlights will dim briefly, but it runs. Also, it wasn't doing this before my partner had at it, but when I shut the key it keeps burning more fuel in a crazy way before it finally dies. Did change the one-piece spark plug wire assembly, the plugs, the distributor cap & rotor, fuel, air & oil filters, (and the power steering pump which the former kid owner had put power steering fluid in, after a hard run it got a pouring leak in it!). And the choke seems to come on and off the way it should.

The oldest Corolla at the local yard is 1988. But wikipedia says these were also sold as a Chevy Nova? which there is an '86 in the yard, I wonder if I could try raiding that carb.

Also the Haynes manual says when a carburetor gets blamed for things there are about 20 or 30 other things to check.

Cou

[verlaryder]

Yes the '86 chevy nova with 4ALC engine has the same carburetor tag number as the '86 Corolla 4 door sedan with 4ALC