96 Camry Idle Issues
 

Hi folks,

My 4cyl Camry (157,000miles) has had idle issues for some time now and I've finally lost patience with it and am on a campaign to diagnose and repair. Here is the pertinent information: Upon a cold start the rpms will jump to around 1000 and then quickly fall and the car will die if I don't revive it by gassing. The general trend is that my car starts much better in frigid cold Rochester, NY winter temperatures than warmer temps.

Here is what I've done recently:
-Cleaned throttle body thoroughly
-Checked for vacuum leaks; there are none
-Replaced spark plugs and wires, distributor cap and rotor, air filter

Here is what I plan to do ASAP:
-Replace fuel filter
-Clean EGR valve (I know the EGR valve wouldn't affect start up idle, but I want to do it anyways)

I know some of you will say to do the idle air control valve, but it was replaced around 80,000 miles ago. I've considered removing it and really cleaning the insides of that but my Haynes manual says I must drain my coolant first so I've avoided that - any thoughts though? I find it strange that the cold starts are infinitely better than warm ones. Could this indicate that one of the many variables that affect the fuel/air ratio is a little off, creating a less than desirable condition upon start up?

Seriously, if anyone provides me with advice that leads to me solving this, I will send you beer.

Thanks!

The engine starts and idles OK when warm? If so check the coolant temp sensor for the computer. ETC sensor.

The can fuel filter seldom plugs up, does the engine have good power?

EGR can cause issues if the EGR valve is sticking open at engine idle.

Spray some cleaner into the opening of the IAC valve. Have the engine running and adjust RPM to prevent engine stall as the cleaning is sprayed inside. Use only a cleaner safe for plastics.

When starting the engine warm this problem never occurs. The idle isn't always smooth, but it never dies on me. Nor does it ever die while driving.

Regarding engine power - not too impressive, it doesn't accelerate quickly and its a little late in its response. I've just always assumed that's normal for a 16yr old 4cyl car. I recently tightened the throttle cable and that helped a little.

Regarding the IAC opening spray clean - I am planning on just taking the IAC valve off and cleaning it that way. Is there an advantage to doing the spray method you mentioned on top of that? Also, I use carb cleaner, is that appropriate?

Thanks for the response.

Taking the IAC valve off to clean is better although most owners just use spray. The valve is supposed to be made of a plastic that is not affected by cleaners but may be best to use the least harsh chemical possible thus something stating safe for plastics. Perhaps CRC brand MAF sensor cleaner.

Might check TPS sensor. If the sensor contacts become dirty engine hesitation can result plus idle issues.

Have you checked the coolant temp sensor for the computer?

I have not checked the coolant temp sensor yet, although it's on my list of things to do this weekend. I'll follow my Haynes manual's procedure and see what happens, I'll update with anything noteworthy.

Update
 

I took apart the entire throttle body, removing the IAC valve to find that it was perfectly clean. I also tested the IAC valve's resistance and it was within specifications. I made sure the back of the throttle plate was super clean too.

I took the EGR valve off and cleaned out the carbon that was nearly blocking the entrance.

I also replaced the coolant temp sensor.

Unfortunately, my starts haven't improved a bit. It seems that the issue doesn't involve the air. Could it be something fuel related?

This car is testing my resolve! The idle issue campaign is being put on hold because my timing belt broke last night and that's my new job this weekend. Lets see how that goes...

Resolution
 

I'm happy to say I know the origin of the idle problem. I had cleaned the port where my EGR valve contacts the manifold, but I never cleaned the moving parts inside the valve. It didn't change anything.

Yesterday I realized if I tap the EGR valve a few times before I start the car, it runs perfectly. I assume that my valve is stuck open and that's the cause of my issues. I guess I'll get in there this weekend and make sure the entire thing is cleaned out.

You seem to have found the cause, good job.

Unfortunate Update
 

Well, I put in a new EGR valve yesterday and today it sputtered and died when I started it. This is disappointing.

It really seemed like the sticky EGR valve was the cause since tapping the top with a hammer before starting the car worked on the old one.

Could the issue be something within the EGR system, or should I look elsewhere?