2001 Camry 4-2.2L - Stalling at idle

[John C.]

Okay, we’ve got one driving us nuts here (I know, it’s a short drive ).

Disclaimer, I’m not a tech... I just pay the bills... and do everything else around here.

So, what we’ve got is a 2001 Toyota Camry LE, 4 cyl. Began with intermittent stalling, when at idle. Customer would drop it off, leave it for a few days (sometimes longer), but we could never get it to stall. Finally told him, it would have to become more consistent for us to even begin to find out what the issue was.

Well, it’s stalling more consistently now, like all the time. Here’s what happens, start the car up cold, it’s fine, let it idle for a while (five to ten minutes) and it stalls. It will start right up, with no problem, but within minutes it will stall again. BUT, when we disconnect the IAC (we’ve replaced it twice already, along with a bunch of other stuff I’ll list in a second) car holds idle.

Here’s what we’ve replaced:
IAC (twice!!!!)
EGR valve
Crankshaft sensor
Coolant temp sensor
Throttle position sensor
PCV valve (it was filthy)

We’re beginning to think ECM????

Thoughts? Ideas? Anything? Please?

Thanks, in advance!

[steven kiser]

I've had a bunch of issues with these little beauties in the past. Disconnect the vacuum line from the EGR valve and see if it stops the stalling issue. I know the valve has been replaced but the switch could be acting up by either staying opened or just to weak to close and at times will cause a stalling issue. If it runs fine and starts stalling again when hose is plugged back in then test switch to see if it's being powered up to open. If not replace it and try it again. If it's being commanded to open you need to find out why. There are a few conditions that need to be met before the valve should open. One is warm up another is rpm and I believe the other is vehicle speed and load. Check into all of these. I believe I read somewhere that a corroded ground wire that's attached to the PCM driver system will cause an issue like this. Another and totally different issue can be a dirty / filthy / gross / neglected throttle body can be the culprit. I've had to literally spend hours cleaning and scrubbing these with a nylon brush to get them clean enough to function properly. I've seen extreme issues with restricted exhausts causing issues like this but I don't think that's your issue here. I would look long and hard at the first option. Good luck.

[brianp87]

The most common things we see are map sensors or map sensor vac lines and coolant temp sensors. What are the fuel trims? Is it running rich. Why were the other items replaced? What is the temp reading on gauge versus the computer?

[nickscarcare]

I am guessing you checked for codes. I just had a 97 in here with the same issues, this one did set a code, it was a faulty MAP sensor. Replaced it and all was good. I did use the OEM part and that was not cheap, but well worth it.

[brianp87]

How did we do on this?

[John C.]

Sorry, we've been really busy (he types, while knocking on wood), so it's been sitting out in the lot all week. We literally just brought it into the shop a few minutes ago, but we probably won't do anything to it until Monday. Not to worry, we'll post our results... no matter how things go.

[steven kiser]

Inquiring minds want to know..................................

[brianp87]

How did we do on this?

[John C.]

Ha, I was planning to post on this sometime today, so I guess now is as good as ever.

We are $#&*ing stumped.

It sat all last week (our lead tech, Mark was on vacation), but prior to that, they increased duty cycle of the IAC, which seemed to make a difference... for a while. They really thought they had it with that, and had me take it on a long drive. Before the drive, it sat idling in our lot for a llllooonnngggg time. Then, half way through said long drive, it began to stall whenever I'd come to a stop, and sometimes as I began braking for a turn.

Then, they figured they'd take a stab at replacing the ECM (used, of course), which brought it right back to the original issue of stalling at idle after it warms up for five to 10 minutes.

When it's running, it runs great!

This car sits A LOT, hence it sitting here for so long without the customer complaining. Although, I'm sure they would like it back at some point.

[brianp87]

The most common things we see are map sensors or map sensor vac lines and coolant temp sensors. What are the fuel trims? Is it running rich. Why were the other items replaced? What is the temp reading on gauge versus the computer?

Im willing to help but ill need more info.

[John C.]

The most common things we see are map sensors or map sensor vac lines and coolant temp sensors. What are the fuel trims? Is it running rich. Why were the other items replaced? What is the temp reading on gauge versus the computer?

Im willing to help but ill need more info.

Will get back on this tomorrow.

[John C.]

The most common things we see are map sensors or map sensor vac lines and coolant temp sensors. What are the fuel trims? Is it running rich. Why were the other items replaced? What is the temp reading on gauge versus the computer?

Im willing to help but ill need more info.

Okay, since starting all this, we have replaced the MAP sensor (although everything tested fine with the original) and lines are okay. Replaced coolant temp sensor (see OP). Not running lean or rich. Temp reading on gauge versus the computer - about the same.

Why we replaced other items: experience with this particular vehicle and symptoms, educated guesses, to now throwing darts (see MAP sensor replacement).

[brianp87]

What are the long term and short term fuel trim readings? I seem to remember voltage issues for the coolant temp sensor causing this. Also does it have an egr if so try it with it disconnected.

[John C.]

Techs tell me they don't remember exact long and short term fuel trim readings, but they definitely were normal. We replaced the coolant temp sensor. First thing we do on a vehicle like this, with this symptom is unplug the EGR (even I know that ) and although it still stalled after unplugging it, we STILL replaced the EGR somewhere along this ri-GD-diculous path.

[brianp87]

Id re-test the temp sensor voltage when the stalling happens.

[John C.]

Hold all thoughts, we MAY be have found something...

[John C.]

Really sorry folks, car is fixed, but things have been very hectic at shop and home. I will give all the gory details, when time permits.

[John C.]

I'll never have time to have this fully explained to me, so that I can understand and write it up, so here's what our new tech wrote on the RO:

"Performed visual and electronic check of all applicable systems. Using real time data to map the input and control functions of the PCM (engine's brain), no abnormalities could be found in the electronic function of the engine. Remove and replace Throttle Position Sensor, one of many sensors used as an input to the PCM for the adjustment of short and long term fuel trim. Removed and Replaced Engine Coolant Temp Sensor to correct rare, but erratic readings found in the PCM. After replacing the above sensors the vehicle would idle for longer between stalling. By adjusting the duty cycle of the idle air control we found the engine would not stall if more air was allowed into the throttle body at idle. The engine's stability when adding more air at idle was evidence of un-metered fuel entering the throttle body. In examining the fuel system from the tank to the engine, raw fuel was found in the evaporative emissions purge line exiting the vacuum duty valve located in the engine bay. This line originates at the charcoal canister and is only meant to purge fuel VAPOR into the intake at light throttle cruise to reduce the overall amount of harmful greenhouse gasses emitted from the fuel system. Further diagnostics proved that the raw fuel had entered the vapor lines due to a manufacturer's defect in the previously replaced (one year ago) charcoal canister. After gravity draining the lines from the engine back, using low pressure compressed air and dry smoke to purge the lines of any liquid fuel, we replaced the charcoal canister, including associated lines and valves as well as the vacuum duty valve in the engine bay. The engine idles properly and exhibits no driveability issues."

Yes, he's a UTI grad and came from a Mercedes dealership (the one just south of you, Steve).

Now, you may ask yourself, why no codes???? We've asked that ourselves, and we can't find an answer. And yes, we replaced more than was in the worked performed description, some needed and properly charged for, others not, and not.

The canister was one week out of warranty, but the dealership actually honored the warranty anyway THAT is a rarity, from a dealership, especially for such an expensive part.

[ricmorin]

Makes perfect sense. The evap purge was allowing raw fuel into the mix during a purge event. The engine stalled as this should only be vapor and was unable to handle it. No codes because the engine stopped running before it new what happened.

[brianp87]

We get faults with no codes all the time. You just have to train yourself that just because there are no codes doesn't mean it cannot be tested it just means it will take more knowledge and time. Good job being persistent and not giving up.