1MZFE Stalling on warm engine restarts

[BaLOBO]

I have a 2000 Camry V6 that seems to have an idle problem. 5-10% of the time I restart the engine when it's warm, the car will idle at 100-200rpm. If I hit the gas pedal, it revs fine but drops back down to the low idle as soon as I let off. It will stall when I put it in drive unless I rev the engine, throw it in gear, and immediately start moving. If I have to reverse out of a parking spot, it becomes quite an ordeal. If I can manage to get onto an actual road and accelerate hard, the idle returns to normal at the next red light and no more problems. It's never happened on a cold start. There are no OBDII codes. The problem has been occuring sporadically for 2 years. I found a previous thread of a similar condition, but there was no listed solution.

What could be causing this intermittent problem? My first thought is IAC valve. What other components could affect the idle speed sporadically like this? Any thoughts welcome....Thanks

[kamrhee]

Bump...

BaLOBO,

Got the same problem here. Only this occurs in our Highlander with the 1mz. Sometimes it would idle fine and sometimes it would idle very low (100-200 rpm). What gives here? I have cleaned the throttle body twice so its not that. I've tried using fuel injector cleaners with mixed result (I would experience the same thing after). Anyway to test fuel filter without taking it apart? Vehicle has about 60+K miles. Oil and filter changes every 3000 mi. or 4 months. Transmission fluid and transfer case fluid have been changed also.

Let me know if you get some tips. Thanks.

kamrhee

[Mike Gerber]

I think your thought on the idle air control valve is a good place to start. Clean the throttle body paying particular attention to the port leading to the idle air control valve. Spray the cleaner liberally down that port.

If the cleaning of the throttle body and idle air control valve doesn't solve the problem, I would next test the coolant temperature sensor. Toyota calls this an ECT sensor. You will need a DVM and the specs from any manual to do this. The sensor may be out of range telling the ECU that the engine is still cold, when it is actually warm. This would result in a richer mixture than necessary to run a warm engine, that could be flooding the engine under these conditions and causing the low idle and the stalling.

Mike

[BaLOBO]

I cleaned the throttle body not too long ago, but only to fix a sticky pedal problem. I didn't spray much down into the IAC port. I will take the IAC valve off and clean it specifically this weekend. Upon further research, my list of possible sources of the problem has grown:

1. IAC Valve

2. ECT Sensor- Don't know what to make of this. Why would it work sometimes but not others under the exact same conditions. I will check the resistance on it.

3. EGR Valve- I think I can eliminate this. If the car is running fine and I turn the engine off, and then restart and get the low idle, the EGR must have been closed previously, and it doesn't open when you start the engine, right? Then there's no way it could be stuck open.

4. Fuel boiling in fuel rail- If this was happening, wouldn't the car refuse to start? And wouldn't it go away almost immediately when the car starts...my idle problem will persist for at least 2-3min. I've never let it sit for longer than that to see if it corrects itself.

Whatever the problem is, it's related to the temperature in the engine or under the hood. I've thought about all the times the problem has surfaced, and it's always a restart of the engine less than 10min after it last ran. Oddly enough, it's never happened after filling up at the gas station. I'll keep you posted kamrhee.

[eyeball96]

My 96 1mz doesn't do what yours is doing, but I'd be interested to know whats causing it, if it ever does!...Let us know how you fix it!

[Mike Gerber]

BaLOBO,

The more I think about your problem, I would have to add a weak fuel pump to your list of possible problems. Fuel pumps have a tendancy to act up when they get hot, like after a warm restart. What you said about it never happening after filling up with fuel at a gas station makes me think of this. Electric fuel pumps in the gas tank are actually cooled by the fuel in the tank. When you fill up, you are putting in a lot of nice "cool" fuel. I would get a fuel pressure gage on the fuel rail and test the pressure of both a cold and a warm engine. You may have a problem with the pump or the fuel pressure regulator. I'm just thinking out loud here.

Mike

[BaLOBO]

Thanks Mike- if I can borrow a gauge from Autozone or somewhere, I'll try and check it. <begin rant>Intermittent problems like this drive me crazy because it's not like you can plan to work on the car first thing Saturday morning, and it's difficult to drop everything and work on the car when you have 2 kids under 4yrs old.</end rant> Does the temperature of the gas in the tank change significantly while driving? I thought the FI system was a "returnless" type, but I may be wrong. I think you're right though; it's worth checking the pressure.

[Mike Gerber]

The pump get's hot as it is working and the gas therefore get's a bit harder to push through the system.

All modern EFI systems have a return line back to the tank.

I would still do the throttle body cleaning and the idle air control valve cleaning first and then check the engine coolant temp sensor, since you can do these items on your own. If the cleaning procedures don't solve your problem and you dont find anything out of spec with the ECT sensor, (remember, you will need a DVM to check the ECT) then I would move on to the fuel pump and regulator pressure testing.

Mike

[marc780]

I ad this problem after i cleaned my tbi on my 2002 V6. I dont know if your engine uses the same part as mine, but here goes: After trial and error i found i had knocked the throttle position sensor out of adjustment! (The black horshoe shaped plastic thing at the left end of the arrow - not what the arrow points to).It was simple to adjust, just remember to loosen the screws and not remove them! Its tough to get back on. Loosen them screws and rotate the sensor and see if this makes a difference to you.

[timebuilder]

Returnless EFI systems have become more popular. If you can get a fuel test setup and can atach it properly, don't just look at fuel pressure. Look at fuel volume as well, specifically one pint in 30 seconds.

Thermistor based temp sensors will allow you to read a voltage across the sensor that you can compare to a chart to see if the temp being reported to the ECM is correct.

I'll check in later.

[uconnkoala]

I had a similar problem last year

Take off your throttle body, and the IAC (Idle Air Control). Use rubber gloves, because the coolant hoses leak all over the place.

Get a toothbrush, toothpick (you'll see), and some SeaFoam - and clean out all the carbon inside the IAC.

Be careful when unscrewing the IAC from the throttle body - I stripped all the screws and had to dremel new slots

Make sure the mechanism can rotate freely and doesn't stick

[njavalonguy]

Originally Posted by BaLOBO

I have a 2000 Camry V6 that seems to have an idle problem. 5-10% of the time I restart the engine when it's warm, the car will idle at 100-200rpm. If I hit the gas pedal, it revs fine but drops back down to the low idle as soon as I let off. It will stall when I put it in drive unless I rev the engine, throw it in gear, and immediately start moving. If I have to reverse out of a parking spot, it becomes quite an ordeal. If I can manage to get onto an actual road and accelerate hard, the idle returns to normal at the next red light and no more problems. It's never happened on a cold start. There are no OBDII codes. The problem has been occuring sporadically for 2 years. I found a previous thread of a similar condition, but there was no listed solution.

What could be causing this intermittent problem? My first thought is IAC valve. What other components could affect the idle speed sporadically like this? Any thoughts welcome....Thanks

Balobo,

I have exactly the same problem as you on my 2000 Avalon with 99K miles...what was the issue and how can it be fixed?

~A

[prlaba]

I have a 2000 Solara (6 cyl) with 174K miles that's exhibiting the same problem mentioned in this thread, except...

In my case, once the car has warmed up, if I start the car and immediately rev the engine above 3K RPM (or thereabouts), the engine idles fine at its normal idling speed (around 800 RPM). If I try to start the car but don't rev the engine, the idle speed drops below 200 RPM and the engine immediately stalls.

My mechanic (not a Toyota dealer) suspects the problem is with the IAC, but wants to run more tests to be sure.

Does this added clue (revving the engine restores the idle to normal) suggest a faulty or clogged IAC, or something else?

Also, given the cost of replacing the IAC (around $400), is there any reason I shouldn't just live with this problem, given that I seem to have a reasonable workaround?

Thanks.

[uconnkoala]

Originally Posted by prlaba

I have a 2000 Solara (6 cyl) with 174K miles that's exhibiting the same problem mentioned in this thread, except...

In my case, once the car has warmed up, if I start the car and immediately rev the engine above 3K RPM (or thereabouts), the engine idles fine at its normal idling speed (around 800 RPM). If I try to start the car but don't rev the engine, the idle speed drops below 200 RPM and the engine immediately stalls.

My mechanic (not a Toyota dealer) suspects the problem is with the IAC, but wants to run more tests to be sure.

Does this added clue (revving the engine restores the idle to normal) suggest a faulty or clogged IAC, or something else?

Also, given the cost of replacing the IAC (around $400), is there any reason I shouldn't just live with this problem, given that I seem to have a reasonable workaround?

Thanks.

Don't bother with spending $400 at the dealer just yet. I'd first try cleaning it (see my post farther up on the page).

Its definitely worth finding a solution, because I previously had times where I couldn't get my car going because I had to rev the engine while standing on the brake just to drive. Not fun.

[njavalonguy]

Touchwood I got lucky....I took it to a local mechanic who sprayed some cleaner spray inside the throttle body without actually opening it up to expose the IAC and it worked for me.

Its almost 4 months and I haven't faced this issue so far.

~A