Occassional stalling on start up?

GTO52 · Jun 9, 2011

My 2002 Toyota 3RZ-FE engine pickup(190000km), started stalling occasionally on cold starts(sometimes hot as well but mostly cold) last year.
The engine starts up but stalls immediatley but then will start and run fine on the second attempt.
There does seem to be a bit of a rough idle when cold.
But if I disconnect one of the leads to the battery and leave it for an hour to reset the ECM the stalling problem and slightly rough idle disappears.
But after +/- 4 months its back?
Could it be a sticky IAC valve?

440Magnum · Jun 9, 2011

Yes, carb cleaners are pretty much the same as TB cleaners, and yes you can do a reasoable job of cleaning the TB and IAC on the car. For the TB, use a rag wrapped around your finger, saturate it with carb cleaner, and wipe the gunk off the throttle blade (both sides- open the butterfly manually and wipe the edges and back side) and then around the interior surface of the throttle body bore.

For the IAC, its more hit and miss. What I've done with success is find where the IAC sucks its air in- there's usually a passage just to the side of the throttle plate, or else its a separate air intake hose from the filter box to the IAC valve. Start the engine, and then squirt short bursts of cleaner into the inlet of the IAC valve. The engine will try to stall (the first few times, it may actually stall), but that will cause the IAC to move to compensate. As you keep blipping bursts of cleaner in there, it will soften the deposits and when the IAC moves to bring the idle back up, the cleaner will pass through and take the softened deposits with it. Its not quite as good as disassembling the valve and physically wiping it down, but on some vehicles you can't do that without a scan tool to retract the IAC valve pintle to prevent damaging it on reassembly.

GTO52 · Jun 9, 2011

I just scared of damaging the IAC valve its very expensive to replace!
Why does the problem go away when I reset ECM?

440Magnum · Jun 9, 2011

Originally Posted By: GTO52
I just scared of damaging the IAC valve its very expensive to replace!
Why does the problem go away when I reset ECM?

Me too, that's why I like cleaning the IAC with bursts of carb cleaner rather thay by removing it!

Going away when you reset the PCM may be simply because until the PCM "re-learns" how the engine behaves, it defaults to a higher idle speed and compensates for the gunked-up throttle body. The first car I ever owned with an IAC valve acted more or less the same way the first time the throttle bodies and IAC needed cleaning. It stalled when hot, and would sometimes also stall or almost stall on the first start, and unplugging the battery would "cure" it temporarily.

If you're really worried that the "spritz" method I described will still damage the IAC valve, then you could just try cleaning the throttle body by hand first and see if that alone fixes it. The IAC may have no problem at all, other than it can't fully compensate for the gunked up throttle plate.

Vikas · Jun 9, 2011

Are we talking about the 4 cyl 2.2 Camry engine? If so, every year I just spray the throttle body cleaner liberally there while revving the engine. I suspect the cleaner also seeps in the IACV and cleans it. I treat it exactly the way I used to treat older carburated cars. The fix lasts about an year before I have to do it again.

- Vikas

GTO52 · Jun 9, 2011

Originally Posted By: Vikas
Are we talking about the 4 cyl 2.2 Camry engine? If so, every year I just spray the throttle body cleaner liberally there while revving the engine. I suspect the cleaner also seeps in the IACV and cleans it. I treat it exactly the way I used to treat older carburated cars. The fix lasts about an year before I have to do it again.

- Vikas

No, its a 4cyl 2.7(3RZ-FE) it was used in the Hilux and Tacoma pick ups.

GTO52 · Jun 9, 2011

On the South African 3RZ-FE engines we have a MAP sensor and not a MAF.

Can the carb cleaner damage the MAP sensor?

Vikas · Jun 10, 2011

The 1999 2.2 Camry also has the MAP sensor. At least on that vehicle, MAP sensor is way out of the direct intake path. I don't see how carb cleaner would reach the MAP sensor.

demarpaint · Jun 10, 2011

Sometimes these problems can be tough to diagnose. Try this, key the engine to the run position but don't start it, hold it in the on position for a few seconds, turn it off, and repeat a second time. Then start it and report back......... You can also check all the basic stuff, vacuum leaks, codes, clean the TB, etc. HTH

SteveSRT8 · Jun 10, 2011

Two vehicles I know had this exact symptom.

On a 2005 300c 5.7 Hemi it was the evaporative canister solenoid. It would dump fuel vapor at idle on startup, thus stalling the motor.

On GM late model V8's it's the IAC not resetting properly. The trucks would still start but they idled poorly under load.

Since the OP's car has these same parts they are suspect.

mechtech2 · Jun 10, 2011

Take them off.
Spray and pray won't work well, if at all.

GTO52 · Jun 11, 2011

I tried the key on/off, it did not stall(it has only stalled once in the last week) but there is a rough idle on cold starts which lasts 30 seconds or so and then its fine.

Rix · Jun 11, 2011

Hose out the throttle body and IAC ports. start it up, rev it a bit to clear the stuff out of it.

There is a "gas filter" that should keep the stuff out of the map sensor.

If you've got injectors going dirty, the wrong spark plugs, sticking iac valve (or beyond it's range of self adjustment) or any other number of things, you'll get this condition.
cleaning the throttle body and iac ports and the correct spark plugs are the 2 most likely.

GTO52 · Jun 12, 2011

Originally Posted By: Rix
Hose out the throttle body and IAC ports. start it up, rev it a bit to clear the stuff out of it.

There is a "gas filter" that should keep the stuff out of the map sensor.

If you've got injectors going dirty, the wrong spark plugs, sticking iac valve (or beyond it's range of self adjustment) or any other number of things, you'll get this condition.
cleaning the throttle body and iac ports and the correct spark plugs are the 2 most likely.

Injectors I had cleaned last year and I had to replace one thats resistance was out of spec causing a intermittent misfire.
But the stalling problem first happened before the injector went bad.

Volvo_ST1 · Jun 12, 2011

I don't know about your car, but on many cars the ECU requires correct coolant temperature data to determine the proper fuel/air mix. I would test the engine coolant temperature sensor. It may be off.

artificialist · Jun 12, 2011

My dad's old 1997 Lexus ES300 did this. There was a way to test IAC function. If you jumped 2 terminals in a diagnostic connector located underhood, the IAC would open enough to rev the engine to a certain RPM. If the RPM was less than that, the IAC was no good, or the IAC passage was full of garbage.

Vikas · Jun 12, 2011

As a I said before, just spray the intake. You are not going to have more problems by doing that.

GTO52 · Jul 9, 2011

I finally got around to cleaning the throttle body and IAC valve.
I cleaned the throttle body with carb cleaner and an old tooth brush and a rag.I then started the engine and sprayed a few bursts of carb cleaner in the IAC valve slot.
But now sometimes the idling sticks at a 1500rpm sometimes 2000 rpm, if I blip the throttle it drops back to normal?

mechtech2 · Jul 9, 2011

If you blip the throttle to get it right, that sounds like the TB is sticking.
The Idle air motor would not respond in that way.

GTO52 · Jul 10, 2011

Originally Posted By: mechtech2
If you blip the throttle to get it right, that sounds like the TB is sticking.
The Idle air motor would not respond in that way.

So the butterfly is sticking?
Is it not seating properly?
Should I spray it some more?

Occassional stalling on start up?

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