Our 2003 Sienna (80K) has been stalling at startup, you can sometimes keep it going with gas, but not always. After reading around a bit, I was thinking the IAC valve might be suspect. My question is can you clean it or service it your self and if so where is it and what does it look like? If not and it should be replaced is it a do-it-yourself deal and what does the part run? Thanks for any help, great forum, always learn lots here.
Yeah, the IAC is a probable cause when it comes to intermittent stalling. Usually cleaning it up will do, but sometimes they do require replacement. Here's a picture, you can see where it's located on the throttle. At the bottom is a cutaway of the valve removed. You can see it mounts to the bottom of the throttle body ahead of the throttle plate. You can start by taking the intake boot/air cleaner assembly off and spraying some off the shelf throttle cleaner in there. Spray that stuff in there and clean it up with a rag best you can. May very well do the trick.
Qslim,
Excellent diagram, thanks for the response. I got into it a bit last night taking some parts off with the intention of taking the entire throttle body off to service it and the IAC - couldn't get the first two of six TB screws to turn at all which was a bummer. It was late so I went ahead and sprayed cleaner down the hole to the IAC on the right intake of the TB and figured I would try it today. We'll see what happens. Thanks again.
Well, I cleaned the TB and the IAC valve and she purrs like new, hopefully the problem is solved. One question while it ran great afterwards the check engine light came on (it wasn't on before) and I was wondering if unplugging the elec connections the throttle body will make it throw a code, and if so, how do I reset it (unhook battery, etc.).
Thanks to the board and especially Qslim since without the diagram provided I wouldn't have likely dove into this. Hopefully the engine light issue can be resolved quickly.
Well, I cleaned the TB and the IAC valve and she purrs like new, hopefully the problem is solved. One question while it ran great afterwards the check engine light came on (it wasn't on before) and I was wondering if unplugging the elec connections the throttle body will make it throw a code, and if so, how do I reset it (unhook battery, etc.).
Thanks to the board and especially Qslim since without the diagram provided I wouldn't have likely dove into this. Hopefully the engine light issue can be resolved quickly.
Any Autozone can reset the light for you! The TB cleaner triped the light, or the intake MAF being disconnected did it.
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Use to work for TMMI, own a '04 Highlander V6, 4WD, 3rd row, now has 125k on the clock.
My family in-law has a '97 Tercel CE Coupe, '03 Tacoma DC, '07 Highlander V6, 4WD, 7 pass. and a '04 Sienna LE!
Well, I cleaned the TB and the IAC valve and she purrs like new, hopefully the problem is solved. One question while it ran great afterwards the check engine light came on (it wasn't on before) and I was wondering if unplugging the elec connections the throttle body will make it throw a code, and if so, how do I reset it (unhook battery, etc.).
Thanks to the board and especially Qslim since without the diagram provided I wouldn't have likely dove into this. Hopefully the engine light issue can be resolved quickly.
If you unplugged the connections with the power off, the system would not set a light. It's probably a P0300 misfire code from the first few seconds of burning that TB cleaner. Disconnecting the battery will reset the light, and you can also pull the fuse labeled 'EFI' from the fuse box under the hood infront of the left suspension tower (pulling the fuse will only reset the light, not other system memory like your radio presets). Just to be safe though, I'd recommend swinging by a chain parts store and having the code retrieved before you reset it. It's good to know what you're car is trying to tell you, and they will hook the scan tool up for free.
On the subject of the IAC valve, when I took it apart to clean it you could tell by the marks on the screws that hold it to the TB it had been done before (cleaning the IAC). We got the car used with 50K on it, now there's 81K . Just wondering if that seems strange to have the IAC done twice inside of 80 and, if so, should I check/service anything else to prevent the issue in the future? Thanks for any ideas.
On the subject of the IAC valve, when I took it apart to clean it you could tell by the marks on the screws that hold it to the TB it had been done before (cleaning the IAC). We got the car used with 50K on it, now there's 81K . Just wondering if that seems strange to have the IAC done twice inside of 80 and, if so, should I check/service anything else to prevent the issue in the future? Thanks for any ideas.
That's not unusual at all, Jeff. Keeping the throttle body clean with a little cleaner periodically will keep it from gumming up in the future.
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