engine hesitation on startup ('99 camry)

Mike, I have a 97 that does something similar. The last time I had mine smogged I was told by the mechanic (who worked for toyota) that there is an IAC(Idle Air Control valve) that is causing the problem. Its located on the throttle body and is about 150-200 to replace. I'm going to take mine out this weekend and see if I can clean it. He said that you can try to clean it. Sometimes it works sometimes it doesn't. It will get worse over time. To the point the car won't stay running. So if its just starting to happen, you might want to try to clean it or replace it to save yourself some head ache. I've done the testing on mine to see if its working like its supposed to, which is to jumper the control in a box that is on the passenger side under the hood, and when you do this the engine rpms will increase for a couple of seconds. Mine did that, but I still have the problem. So I'm just going to clean it. I'll post back and let you know how it goes. So far I have 150,000 on my car. Hope for another 150,000

Jimmy

snipped-for-privacy@gmail.com wrote:

The IAC part itself retails for $222 with installation being another $135 at a $90 per hour labor rate. Just so you know what to expect at your local dealer. Wouldn't trust the gang at Firestone or Pep Boys to complete the repair, the Toyota Techs do allot of these replacements and are very good at it. Trouble is, it'll come back again, whether you clean or replace. It's a function of the car getting older and running dirtier, so get used to it and welcome to the IAC Club, they're hundreds of thousands of members. Since the valve goes Gaga on every Camry out there, you're in good company.

The IAC will continue to be a problem. It's a design issue. Daniel has an excellent post on how to solve the problem with Triflow. Yes, 1800 rpm with these engines is normal, it's a short cut to try to get the engine warmed up and cut emissions.

Do avoid spraying throttle body cleaner into the electrical side of the valve. You may need to buy a new IAC rubber gasket. I just reuse the old one if it's not damaged, but it's good to have one handy just in case. You don't want any coolant in the mixture from the IAC. Do a search on cleaning the IAC.

Check AutoZone's free online repair guide on the 96 on the IAC.

From: Daniel - view profile Date: Tues, Nov 29 2005 7:28 am Email: "Daniel" Groups: alt.autos.toyota.camry

My answer is part conjecture, and part speculation but seems to have worked for me. I used to clean the idle control valve ("IAC" - idle air control valve) with carburetor cleaner, when people said better to replace with new for more durable results. Since it seemed to need cleaning more frequently, I replaced it and followed all the procedures in the Factory Service manual for the associated throttle body removal and cleaning.

Then the problem recurred!

I had deconstructed the old IAC valve just to see how it was put together. IIRC, it had a bimetallic thermostatic coil on one end and an electromagnetic coil on the other. There is a cylindrical shaped piece of metal that rotates to open a port, but this is metal to metal contact with no provision for lubrication.

So I began using TriFlow spray lubricant with Teflon and it seems to work quite well. A small amount can be sprayed into the rectangular opening at the bottom of the entrance to the throttle body which is the air inlet to the valve. I've tried spraying both cold and warm, depending on conditions. Seems to work well for me. I was not about to replace that valve again after having installed a factory fresh one and having the problem recur.

Ok, no throttle body cleaner. I sprayed a bit of Triflow in there just today, with the engine cold, and when I started it up, voila - lower cold start rpms - about 1200 rpm.

Will keep an eye on it.

Thanks,

Michael