The car will start and run as long as I hold the accelerator in. I searched this forum and saw a similar problem and the suggested fix was clean the IAC. I did that and cleaned the MAF. The car started and idled two or three times after this. I put my tools away and tried starting it again but the original symptoms returned. I have a Haynes manual and checked the resistance between the E2 and THC? terminal(sorry I don't have the book in front of me right now but I think it was THC).THe resistance I read was 3megohms and the book called for values in the kohms. Does anyone know if this is a sure sign of a bad MAF unit? I ordered a MAF and plan to check the resistance before installing. Any other possibilities?
Does anyone know if this is a sure sign of a bad MAF unit? I ordered a MAF and plan to check the resistance before installing. Any other possibilities?
Any sensor that is out of specified range by several orders of magnitude is definitely bad. By definition. Or are you asking if you could have set/read the multimeter incorrectly?
You've already identified the other most likely cause, the IAC. If you've already cleaned it and ordered a new MAF, I'd check all connections and wait for the MAF. Of course, borrowing a scan tool that will show you data might help you be more certain.
Thanks for the reply TedL.
I got the new MAF today and it checks the same as the one on the car so I didn't get it. I'm not sure which way to go from here. I guess I'll check the TPS and maybe backprobe the MAF and test the voltages the Haynes manual suggests. If anyone knows of anything else I'd love to hear from you.
TedL thats pretty much what the Haynes manual has. Looking at the MAF the Haynes says the second pin from the left is E2 and the center pin is THA. The new one right out of the box measured in 3 meg one way and 6 meg when I reversed the leads. Which is the same as the one on the vechicle. Does your service manual spec out which pins are which?
Sonic2wb yes the CEL is on. I had the code checked and it says it is a faulty o2 sensor ckt. I didn't think an o2 sensor could cause the engine to stop. Is it possible?
My 99 FSM specs the resistance between terminals THA and E2 at 2.21 -2.69 k Ohms at 68 degrees F. Sounds like what you had for a spec.
It also gives an operational test, looking for fluctuating voltage.
Have you tested the IAC?
I'm with you Ted. This sounds more like an IAC problem. Sometimes you don't always get it clean enough to operate properly. And, sometimes they malfunction even when they are perfectly clean.
I'm with you Ted. This sounds more like an IAC problem. Sometimes you don't always get it clean enough to operate properly. And, sometimes they malfunction even when they are perfectly clean.
The way I read this test it sounded like the engine should be running to do this. I did test the resistance on the plug and they checked ok. I'm not 100% sure I cleaned it enough or cleaned it right. I couldn't see down into the ports. I should mention that I tried a trick I saw on YouTube and sprayed a very small amount of choke cleaner into the port while still on the throttle body because it was late in the day. The next day I took it completely off and tried cleaning with an electrical cleaner.
I am on board with TedL and artbuc, the IAC can be cleaned, but in some cases, and more than you think, they can't be cleaned enough and just need to be replaced. If you do replace it, do make sure you get a new gasket with it because it is a rubber one like an Oring and it won't be reusable.
FYI: An OEM IAC (22270-0A040) is $247.99 MSRP and TN member would pay $173.59, the gasket (22215-20010) is $4.06 MSRP and TN member would pay $2.84. I do sell OEM parts to TN members for 30% off MSRP and I only charge actual shipping costs plus $1.00 - $2.00 for materials.
Even if you don't buy from me, if you ever have any questions, or need information, feel free to contact me.
Generally a sensor that's not working should not cause a condition where it stalls like that. Input that far out of range will be ignored, and a fail safe value used in engine control calculations. AKA "limp in" mode. Mechanical failure of the IAC, however, cannot be compensated for.
However, is there anything else you haven't said that might be relevant, like the MIL on?
Did you do any work on it shortly before the problem cropped up? These are rather expensive parts to be swapping. On the other hand, if you want to go for a new IAC, Gary is the man to see.
If it were me, I would listen carefully to what TedL has to say, he if very knowledgeable when it comes to this generation of Avalon. He is absolutely correct when he asks if there is something you have not mentioned, because the parts are expensive to just be throwing at it.
I like to sell parts, but I want to sell the ones that are going to fix the problem and not just for the sake of selling parts. So lets be sure of what we need and do some good old fashion diagnosing.
TedL thats pretty much what the Haynes manual has. Looking at the MAF the Haynes says the second pin from the left is E2 and the center pin is THA.
Sorry I did not initially take this as a request for confirmation. My '99 Avalon FSM shows the MAF as having five pins (or at least 5 pin positions) and THA is far right, with E2 next to it. So, you may have been running the test incorrectly. Check parts listings to see if the same is used for both years.
In any case, if your pin out is different, you need to determine why your equipment/procedure is showing both the old and new parts as bad. Not something to blow past, because you'd be working on faulty data.
The way I read this test it sounded like the engine should be running to do this. I did test the resistance on the plug and they checked ok. I'm not 100% sure I cleaned it enough or cleaned it right. I couldn't see down into the ports. I should mention that I tried a trick I saw on YouTube and sprayed a very small amount of choke cleaner into the port while still on the throttle body because it was late in the day. The next day I took it completely off and tried cleaning with an electrical cleaner.
Did you apply voltage to confirm IAC opens and closes?
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