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Discussion Starter #1
I had to make a pretty aggressive stop the other day. Right after I stopped I noticed that my truck was idling high (1995.5 2.7). I figured it would go away but it hasn't. Here are the symptoms.

1) Start the truck and the cold idle appears to be normal
2) Once it warms up the idle slowly climbs to around 1700
3) As I drive if the RPMs are lower than this (example in 3rd gear going slowly) when I depress the clutch the rpms quickly drop to around 900 and bounce up to 1500 or so twice. Then the idle climbs to 1700 and stays there.

I cleaned my intake and IAC this afternoon with no change. I visually inspected vacuum hoses and tried to listen for any leaks. I can't find anything.

Any ideas what I could try next? The plunger that pushes on the throttle control (I believe this is controlled by the IAC) isn't touching the throttle at all when it's running. It only makes contact when I shut the truck off.

No CEL's and it's running fine otherwise.

I attached picture to show the gap between the idle control when off and running. Is this normal?

Thanks!
 

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Discussion Starter #3
Thanks, couldn't figure out what that was called. I ordered a throttle position sensor today to see if that's the problem. Watching the TPS with a scan tool doesn't show anything erratic though. At idle it sits at 9.8 and the max it hit while driving was around 20.

Think it's more IACV than position sensor? Might have to replace that also.
 

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NorCal Chapter Pres
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Is your butterfly closing all the way?

I chased a high idle on my truck for a year ir two on my 5vz. Turns out i thought the iac is clean. But when you clean the tb, the gunk runs to the lowest point, the iacv.

I took the entire iacv apart (not recommended by the manual and i see why, it was a pain) cleaned everything and lubed the bearing. High idle problem went away.

Not saying thats your issue, but the icv may be dirty, when you think its clean. If you rotate the valve in there and it sticks at all, its worth disassembling and cleaning.

Main thing is theres a plate with a thermostatic spring. You can rotate this plate in relation to the housing. Make sure you mark this and put it back together the exact same way

Sent from my SM-G920V using Tapatalk
 

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My truck did this a few years ago when my TPS was on the way out. It was erratic though. It eventually lead to a CEL. So you checked the throttle position with a scan tool while your truck was actually idling high and it was normal?
 

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Discussion Starter #7
Truck has been better with the new TPS (high idle is gone), but the low idle goes to low sometimes now and I have to catch it at lights before it stalls. I'm going to replace the IAC next (cleaning isn't helping). I'm having trouble figuring out which IAC part number it is though. Because my truck is a 1995.5 most sites say "this part won't fit" because their system shows it starting at 96.

Does anyone have the IAC part number for a 1995.5 2.7?

Thanks!
 

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Did you try running propane/butane throughout the engine bay around the hoses to guarantee that you don't have a vacuum leak somewhere? If there is a leak that you missed, it should cause the idle to do strange things as the gas is ingested.

If you have an OBD-II scanner, it would be interesting to reset the ECU and then see if all of the OBD-II Readyness checks go into the ready state within about 50 miles of mixed type driving. If they don't do so, you might get pointed in the right direction by the test that hasn't triggered a READY condition yet.
 

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Discussion Starter #10
If I use mine VIN it appears the part number is 22270-75020. This part is super hard to find (if you do find it the price is $250+). Does anyone know what the difference is to the 22270-75030 part? Both parts say they fit a 95 Tacoma 2.7 and they both look the same.

I replaced a bunch of vacuum hoses tonight and cleaned everything again. I also pulled the battery because I read you have to reset the throttle position sensor when you install a new one so it learns ago. Test drive went great, idling perfect, smooth, etc. I then pulled into my driveway and was letting it idle while I fixed the clock/radio. I randomly revved it up to about 3k and when the idle came down it stalled. Now when I start it, the idle will be perfect until I rev it when it won't stay running. I'm at a loss.

Thoughts as to why it runs great until I idle it quick? Also turning on the A/C which causes the idle to jump fast also makes it stall.

Thanks!
 

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NorCal Chapter Pres
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Really sounds like a iacv. The computer only manipulates the timing and the iacv when the ac kicks on. At least all i can see on a scanner...

Ever try completely disassembling the iacv as far as you can? Figure if youre going to replace it you have nothing to lose...

Just mark the plate thats adjustable before removing it.

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Discussion Starter #13
I want to document the parts for future reference. I hate threads that say "fixed it" without details.

1995.5 2.7 4WD 5 Speed
IAC OEM part number = 22270-75020
IAC OEM gasket = 22215-75050

Just for reference the IAC on this year truck is very expensive. Dealership wanted 2 months to get it and $399. Online it was around $275, local auto parts stores didn't have it. They also didn't have the IAC gasket.

So I took everything apart again and cleaned the IAC as best as possible (removed as much as I could and used little wooden dowels to rotate / hold open the IAC as I carefully cleaned inside with a variety of tools and almost a full can of carb cleaner.

I had already replaced the throttle position sensor but the one I used wasn't a Toyota OEM part. I figured while I had it all apart I'd put the original one back since it didn't fix the issue. On this 2.7 the TPS can slide back and forth (screw holes are slotted). I centered it again (like I believe it was originally) but now I have a slightly high idle. I've read mixed things about the TPS on this engine. Some people say you have to calibrate them, others say it will do it over time itself (when it learns). I pulled the battery (which was also suggested) to help it learn but it's still idling a bit high.

Does anyone know if the TPS has to be adjusted to set the idle or will it learn over time?

Thanks!!
 

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Discussion Starter #15
Thanks ShowStop, I tested the resistance between the old and new but I didn't know what the values should be. Do you have a link to the values at full open and full closed? I assume I loosen the screws and turn slightly until these align with the set values?

MAF is visibly clean, no build up on it at all. I have a BT ODBII scanner / app but I'm not sure it gives me MAF readings. I've replace the throttle body boot, and the majority of the vacuum lines that I can get to. Listening you can almost hear a little bit of a leak somewhere but it could also just be air moving through things because it's running. Any other easy way to check for a vacuum leak? I don't have a blow torch to try the propane test.
 
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