Hi, my old 92 camry V6 stutters when I start the engine after a long rest overnight. It started happening after I replaced my air filter, but I doubt that is the cause of the stuttering.

What happens is that in the mornings, when I start my car, it starts fine but the engine starts reving up and down slightly. When I drive the car for the first 10-15 minutes, it is extremely unresponsive and stutters as I apply the gas pedal. Only after going faster than ~35mph, does the engine go back to normal operating conditions or after I drive the car for more than 15 minutes.

It almost sounds like my engine is choking on something, or that a belt is loose. The stuttering jerks the entire car... can anyone help me diagnose this problem?

Thanks a bunch!

If you have the four cylinder, you need to look at the "idle air control valve" or IAC.
The computer controls idle speed by regulating air flow through this valve on the underside of the throttle body.
Fairly common problem.
You can probably get relief by spraying emissions control safe carburetor cleaner into the small rectangular opening you see at the bottom of the throttle body throat with the engine stumbling cold. Just a few short, light sprays, should clean the valve and restore cold idle, and smooth cold start.
That worked for me for about three years.
Then I replaced the IAC, using the factory service manual as a guide.
They direct you to a prior section in the manual for removing the throttle body (TB).
There is also a section re: cleaning the TB (needed to buy an air compressor), and adjusting the TPS (throttle position sensor) and throttle positioner.
On my 1994 with 126,000 miles, the TPS needed adjustment (idle contacts to open at .024" - mine didn't) and throttle positioner to show 1,500 rpm after disconnecting and plugging its vacuum line and releasing the throttle from 2,500 rpm.
Also some dark brown gummy residue came out of the smallest vacuum orifice at the top of the throttle body in back after cleaning with solvent and blowing out with compressed air. Those vacuum feeds lead to the EGR modulator, so they improve smoothness in driving, but not directly related to cold start.
Also found the EGR valve has a port near the back of the TB, and there was a groove that looked like air exit port for the IAC that was black but not obstructed.
After buying the new IAC, I took apart the old one just to look inside and there were some light grooves worn into the surface of the cylindrical drum that rotates to progressively open the "window" type opening in the valve.

There is a small possibility that changing the air filter did have something to do with it. Check the vacuum tubing around the air filter box for vacuum leaks, especially the big tube running from the air filter box to the throttle body. It's possible that it could have become dislodged or has a crack in it. This would allow unmetered air to enter the throttle body causing the stumbling you describe. Also, with the engine idling, listen for vacuum leaks in that area.

Mike

If you have the four cylinder, you need to look at the "idle air control valve" or IAC.
The computer controls idle speed by regulating air flow through this valve on the underside of the throttle body.
Fairly common problem.
You can probably get relief by spraying emissions control safe carburetor cleaner into the small rectangular opening you see at the bottom of the throttle body throat with the engine stumbling cold. Just a few short, light sprays, should clean the valve and restore cold idle, and smooth cold start.
That worked for me for about three years.
Then I replaced the IAC, using the factory service manual as a guide.
They direct you to a prior section in the manual for removing the throttle body (TB).
There is also a section re: cleaning the TB (needed to buy an air compressor), and adjusting the TPS (throttle position sensor) and throttle positioner.
On my 1994 with 126,000 miles, the TPS needed adjustment (idle contacts to open at .024" - mine didn't) and throttle positioner to show 1,500 rpm after disconnecting and plugging its vacuum line and releasing the throttle from 2,500 rpm.
Also some dark brown gummy residue came out of the smallest vacuum orifice at the top of the throttle body in back after cleaning with solvent and blowing out with compressed air. Those vacuum feeds lead to the EGR modulator, so they improve smoothness in driving, but not directly related to cold start.
Also found the EGR valve has a port near the back of the TB, and there was a groove that looked like air exit port for the IAC that was black but not obstructed.
After buying the new IAC, I took apart the old one just to look inside and there were some light grooves worn into the surface of the cylindrical drum that rotates to progressively open the "window" type opening in the valve.

Daniel, thanks for your help! I have the V6 engine. It has gotten warmer recently here in California, and I no longer get the stutter, but I'm sure it's still there. Where can I find the "emissions control safe carburetor cleaner"? Also, I have no idea how to adjust the TPS and no tool to do it. I'll check my air filter, but I'm certain it's an engine problem.

Someone else on the camry forums has the EXACT same problem as I have with the EXACT same car. Could it have something to do with humidity and water vapor getting into the cylinders? I checked all the valves and pipes of my engine to what I can see, and nothing is loose or broken. I just hope this won't be expensive to fix because my car isn't even worth that much anymore.

Sorry to diverge from the main topic, but I've also noticed that my camry has gotten significantly weaker over the years. I'm sure this is natural for an aging car and since I'm no mechanic (or even close), I only know how to do regular maintainence. Is there something I could do that's relatively simple to get some of that lost power back? or some common car "mods" that auto guru's do to almost every car they purchase?

Sorry to diverge from the main topic, but I've also noticed that my camry has gotten significantly weaker over the years. I'm sure this is natural for an aging car and since I'm no mechanic (or even close), I only know how to do regular maintainence. Is there something I could do that's relatively simple to get some of that lost power back? or some common car "mods" that auto guru's do to almost every car they purchase?------------------------------------------------------------------------
See:
http://www.redlineoil.com/products_fueladditives.asp

Take the time to read their technical data section all the way through so you understand why it is necessary to continue regualar use (small amount each tankful) for best results.
Should bring back a lot of that lost "pep", safely and gradually, without the use of harmful solvents.

Hey, I'm back. I have been quite busy lately and I just ignored the stuttering for the time being. I took a good look at my engine last weekend and noticed that it was in pretty rough shape, normal for a '92 car?

Well here's a list of the problems I have for the car:

-Stuttering still continues, I've inspected the air filter, but it seems like something else is causing it. I've now been able to pinpoint the stuttering to only happen on a cold humid morning. When it stutters, I hear liquid slushing as I press the gas pedal as if there was water or oil in the cylinders themselves. The sound the car makes is very similiar to someone sucking liquid from a straw just before all the water is gone, and only a gurgling sound is heard.

-I also have an oil leak around the cylinder head gasket of the 3 cylinders closest to the front of the car. I think I may need to replace the cylinder head gasket for this. Could this be the cause of my stuttering? Water and humidity escaping into the cylinders and causing a disruption in the firing of my spark plugs?

-Also, the car seems to be weak when given full throttle. "Flooring" the car doesn't seem to give as much of a boost in acceleration, even worse than my '99 Rav4. I have no clue what the cause of this is, or how to fix it, or if it's normal for the camry?

-The entire engine and parts are all dusty, greasy, and looking rather old. The foam insulation on certain pipes are crusty and wire wraps are warped. I don't think any of this is serious, but I would really want to clean up the engine.

I know this is alot to ask in one post, but would someone PLEASE help me with one or a few of the problems I've listed? It would be VERY kind of you and I hope I can share what I've learned throughout all this with other AF'ers. :D

Thanks alot!

anyone?