Possible IAC problem??? - Toyota Nation Forum : Toyota Car and Truck Forums

usmc2801 · 02-16-2010, 05:48 PM

First off, just want to say hi as I am new to the forum, I recently picked up a automatic 1990 Toyota Corolla (4AFE) for a winter car. I have been having issues with the car at idle, but only some days not all. For instance this morning after remote starting the car, I went outside to hear the car having a stutter in the motor, as I went to leave the car seemed to choke going down the road so I pulled it back in the driveway and sprayed carb cleaner into the intake while at idle, few minutes later it cleared up and drove to work fine. When I went to leave work it was fine until I stopped for gas, when I went to start it up, at first it wouldn't start then when it did as soon as I put it in drive it shut off, started up again and had to give it gas as soon as it was in drive so it didn't shut off. It had a minor stutter when I got home but once again cleared up a few minutes after spraying carb cleaner directly into the throttle body. Is this an issue with the IAC or some Temp Sensor or am I overlooking something?

Thanks in advance.

1990rolla · 02-16-2010, 09:10 PM

my moms avalon had the same symptoms and it turned out that the iac was so dirty that the little valve inside would get stuck, i took it out and cleaned it with some carb cleaner and a toothbrush and the problem went away. i would just clean it and go from there anyways it doesnt cost anything to clean it.

Bitter · 02-17-2010, 12:55 AM

do the earlier 4afe's have a cold start injector? there could be an issue with that.

90 GP · 02-17-2010, 03:42 AM

There is a cold start injector so that and temp sensor that controls it could be bad. For the IAC take off rubber air intake and look at the square hole in the bottom of throttle body ahead of the throttle plate. With engine running (cold) you should feel suction when you put your finger over the hole. When hot you shouldn't feel suction. Can try spraying carb cleaner in hole to free it up. The cold starter injector richens mixture till engine warmed up. The IAC raises idle speed till engine warmed up.

usmc2801 · 02-17-2010, 07:40 AM

Ok, tonight when I get home from work I am just going to remove the IAC and give it a good cleaning, is it 2 bolts or 2 screws holding it onto the throttle body? I am hoping bolts so there is less likely a chance of stripping them but I have been told most cars IAC is held on with phillips head screws.

90 GP · 02-18-2010, 04:27 AM

If the IAC cleaning doesn't solve problem check the MAP sensor vac line. It is mounted in the middle of the firewall and has a vac line that connects to intake manifold. Check that vac line for leaks/holes. Any air leaks in that hose and you can get that bad idle. Also the fuel filter could be partly plugged up. It is located low near charcoal canister. It is easier to get to with charcoal canister and air filter box removed.

***Kiwi-Corolla*** · 02-18-2010, 11:11 PM

Quote:

Originally Posted by usmc2801

Ok, tonight when I get home from work I am just going to remove the IAC and give it a good cleaning, is it 2 bolts or 2 screws holding it onto the throttle body? I am hoping bolts so there is less likely a chance of stripping them but I have been told most cars IAC is held on with phillips head screws.

If it's the same as my 5A-FE then it'll be four phillips head screws. Make sure you put a lot of downward pressure on them as they're easy to strip, especially when they get old and brittle from heat.