Car question

[glatt]

Changed the plugs and wires, and it's working well now. Or at least for the 2 minutes I let it idle. We'll see how it does after running errands.

I suspect that the intermittent stalling problem was a separate issue, and may crop up again. But after considerable research, I suspect that the engine coolant temperature sensor is the culprit. Apparently a lot of Camry owners have had this problem and fixed it by replacing that sensor. But there's an easy test. If the problem manifests itself again, I just unplug that sensor. If it gets better, it was the sensor, and it needs replacing.

[tw]

Originally Posted by glatt

But after considerable research, I suspect that the engine coolant temperature sensor is the culprit.

If the sensor was defective, then charts from the Car Chip for that sensor would make the defect obvious. The sensor would report engine temperatures that make no sense. Or that change suddenly.

[glatt]

I never got a car chip report from that sensor that also happened at the same time the symptoms were occurring. The car chip is neat, but it can only track 4 things at a time. If you pick the 4 wrong things to track, it doesn't help you. When I did watch the temperature, it was normal and the car behaved normally. That's the big difficulty with this intermittent problem. How can you study a problem if you can't recreate it consistently? After I had settled on this sensor being a problem, the car behaved perfectly, so I couldn't test the theory by just unplugging the sensor when the stalling happened, and seeing if the car improved.

But I did check the resistance of both the new sensor and the old sensor at room temperature, and they didn't match. I played with the old sensor by running it under hot water, and it was cool watching the resistance change as the water got hotter. So the old sensor did something. Not sure if it was the right thing.

I'll tell you this though. My wife was talking about selling the car if this kept up much longer. So I didn't have the luxury of doing nothing and just waiting for the problem to happen again so I could study it some more. A $30 educated guess is OK with me. Better than losing thousand by having to get rid of the car and find a new one.

Based on a few different posts at Toyota Nation, where people had this exact same problem, and the ECT sensor was the culprit, I'm fairly confident this is going to fix it. We'll know if the car doesn't stall before the end of March. 2 months is the longest it ever went without stalling. I may be eating my words. We'll see.

[tw]

Originally Posted by glatt

I'll tell you this though. My wife was talking about selling the car if this kept up much longer. So I didn't have the luxury of doing nothing and just waiting for the problem to happen again so I could study it some more.

What!!! She wants to take away your fun?

[glatt]

Originally Posted by glatt

Based on a few different posts at Toyota Nation, where people had this exact same problem, and the ECT sensor was the culprit, I'm fairly confident this is going to fix it. We'll know if the car doesn't stall before the end of March. 2 months is the longest it ever went without stalling. I may be eating my words. We'll see.

Did I mention that the car stalled again about two weeks ago, a month or so after switching that sensor?

So I widened my search of potential problems. I tried to take the Idle Air Control valve off to check it and possibly clean it. I had trouble because the phillips head screws are difficult to reach, and lock washers make them very hard to remove. I could feel that I was stripping them, so I stopped. Instead, I took off the entire throttle body, to which the IAC vavle was attached. Brought it inside, clamped it in my bench vise, and used vice grips to remove those now slightly stripped phillips head screws. I took the IAC valve apart, and cleaned it thoroughly. Also cleaned the throttle body. Both were a little dirty but not too bad.

Then I replaced the air filter. I had thought it wasn't dirty, but when I compared the new air filter to the old, the old was clearly pretty dirty.

A week went by with no stalling, but the cold start up idle is slower than it should be now. It's at about 800, which is normal for warm idle, but pretty slow for cold idle. Once it warms up, the idle stays at 800 and feels good. I'm hoping it's just that the computer needs to learn how to react to a clean IAC and it will fix itself after a while driving it.

Then on Sunday, I pulled the Exhaust Gas Recirculator to make sure it was clean. It was slightly dirty, but not bad. The valve seemed to open and close properly. But I cleaned it anyway and it's really nice now.

I keep being impressed with myself when I take all this stuff apart and put it back together and the engine fires up.

I think now I just drive it around for a while and see if it stalls again. It seems to go a month or two between stalls.

One thing I recently realized is that it only stalls for me. Something about the way my wife drives doesn't seem to bug it. So either my driving style is really hard for it, or moving my seat back sends some sort of electric signal to fuck it up, or perhaps most likely, my key chain is too heavy and it's messing up the ignition switch intermittently. How do I test for that? Wiggle the keys when it's stalling?

[tw]

Originally Posted by glatt

I think now I just drive it around for a while and see if it stalls again. It seems to go a month or two between stalls.

So what was Car Chip monitoring? And what did Car Chip record with the stall?

[glatt]

The thing that jumped out to me with the data from this "stall" was that the voltage was fluctuating a little bit on this trip in a way that it doesn't normally. Almost like the alternator is flaking out on me.

Here is the data from the trip when it *almost* stalled. At the point of the green arrow, I was stuck behind some slow cars, and felt the engine stumble. Because I was still moving, I didn't want to shift into neutral and give it gas, but I also couldn't give it gas without rear ending the car in front of me. It almost stalled, and in fact the oil light even came on because the engine was going so slowly the oil pump wasn't pumping hard enough. A couple other lights came on too, but they all went out a moment later. When we came to a light and stopped a couple blocks later, I shifted into neutral and gave it some gas throughout the red light. I repeated this behavior for the next couple minutes of the trip.

[glatt]

And this is the voltage. In other trips, the voltage remains steady at around 14 volts, but on this trip, it was fluctuating. You would expect it to drop a lot when the RPMs went down to 200 or so, but it was dropping even before then.