3fe Increasing idle, dies when accelerating (1 Viewer)

Joined
Nov 14, 2019
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Orang County, CA
Today while driving in the heat, my 92 with a 3fe had a low/rough idle (first symptom) while in drive.

I stopped not far from there at a stop sign, idle maintained a consistent 625 or so RPM, (became very smooth, more so than I'm used to) went to accelerate and it died.

Couldn't immediately restart until I turned the ignition all the way off. Once I shut off and turned ignition back on it fired up, accelerated fine, used 2 feet to drive the rest of the way home because I was worried the low idle was the issue.

Got it home and put in park, idle increased steadily to about 2k rpm, pressed the throttle, died on my. Restarted, same increasing idle issue, pressed on gas gently, accelerates fine, pressed on accelerator quickly... died again.

After a few minutes shut off it starts and idles fine. Gets to running temp, idle increases and have the same trouble with it dieing when pressing quickly on the gas, but not when gently (very gently) pressing on the accelerator.

Haven't troubleshot much yet besides pulling wires off the TPS to see if it had an effect ( idle jumped up 150 rpm and back down when plug replaced but the idle acted the same just with that slight rpm change being the only outlier).

Brand new vacuum lines all around about 2 months ago, intake boots also replaced. AFM from thh same period camry (carolla?) That I also found on here.

See some posts about the coolant temp sensor playing a part or the TPS.

Any ideas?
 
Joined
Nov 14, 2019
Messages
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Orang County, CA
I should clarify, no chance if a leak, but could potentially be a vacuum issue if something is clogged or egr went tits up. Otherwise the vacuum system is sealed tighter than a ducks butt
 
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New Jersey
There is an interaction between the IAC and the TPS. The ECU needs both to properly supply fuel and ignition timing.
When you turn the key off, the ECU resets IAC. That's that clicking sound you hear every time the ignition is turned off.
It stalls out because the ECU can't tell where throttle is and can't adjust for fuel.
There are tests for each of these in the FSM.
 
Joined
Nov 14, 2019
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Orang County, CA
Thanks Jon for the recommendation. I dont have a FSM, unfortunately (I know shame on me). Replaced the TPS with some help from other forums, didn't fix it so guess I'll see if I can find something on testing the IAC before I make that purchase.
 
Joined
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Orang County, CA
After a week or so of driving and cleaning the dashpot the high idle came back. Always at operating temp. I ordered a refurbished IAC, still haven't tested the current one as I didn't find a thread on exactly how to test (lots of FSM referrals). Wondering if it could be anything else besides the IAC. The new TPS gives me a much smoother idle when acting right than I had before at least.
 
Joined
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Southwestern AZ
For $20 you can download the FSM from http://techinfo.toyota.com/
It may take awhile but everything can be downloaded section by section
Or contact Jon Held (link in his signature line above) to order a disk where he has done all that for you plus has added some goodies.
 
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Joined
Nov 14, 2019
Messages
38
Location
Orang County, CA
Thank you for the recommendations for the FSM

Tested the IAC and needed to replace it. I replaced it with an IAC that tested good and my idle issues went away... for about an hour and they are back. At a loss, saw another thread advising to adjust the dashpot and throttle stop screws... gonna tinker with that for a bit but does anyone have any other ideas?
 
Joined
Feb 5, 2019
Messages
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Southwestern AZ
Every time you tinker with stuff under the hood it is a good idea to reset your ECU (pull EFI fuse or remove battery terminal for 15 minutes or so) so it can re-learn everything.

Have you tested the AFM and coolant temperature sensor?
 
Joined
Dec 8, 2006
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It is also important to remember that the ECU has very limited windows for sensor fluctuation.
All mechanical adjustments must be done first or the ECU will not be able to "pull" things back to spec.
Follow procedures in the FSM before relying on internet threads.

Is the throttle cable adjusted correctly and can it move freely without binding? There should be slack at idle position to allow the throttle plate to fully close.
Is the cruise control actuator moving freely without binding?
Is the transmission kick down cable able to move freely without binding?

Don't overcomplicate a tractor motor from 1986.
 
Joined
Apr 25, 2020
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Modesto, CA
I had a high idle issue in my 92 that wasn’t quite like yours, but after all the FSM diagnostics, it turned out to be caused by clogged coolant lines in/out of the IAC. Wouldn’t hurt to make sure yours are clear.
 
Joined
Nov 14, 2019
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Orang County, CA
I appreciate the advice, I changed all coolant hoses as part of the baselining when I got the truck last November with several coolant flushes, those hoses are easy to get to so I popped them off and they seem to be getting plenty of flow.
 
Joined
Nov 14, 2019
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Orang County, CA
Changed the IAC and reset the electronics. Ran fine for about 60 miles split up around a week and the issue came back. Could it be the EFI relay?
 
Joined
Nov 14, 2019
Messages
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Location
Orang County, CA
Seems to run fine when I let the electronics reset with the positive battery cable disconnected. After driving and getting hot for a while it reverts back to this issue. If I dont let it stay warm for a while, <20 minutes, I don't have the issue. CEL comes on very briefly when the issue comes back but always goes away and is never persistent enough for me to read it.
 

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