22RE occasional idle bounce
Mar 15, 2025 | 05:09 PM
#1
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22RE occasional idle bounce
Hey folks, trying to troubleshoot an intermittent idle issue on my '86 Pickup (manual, 4x4, no AC).
The truck always fires right up, hot or cold, and runs great. It usually idles, both hot and cold, steadily at 850rpm. It's never gone into a high idle when cold, which may be a separate issue. Occasionally, throughout the past couple years, usually when it's raining or very humid, it will idle about 2-300rpm higher than normal. However recently, when coming off throttle, the idle will bounce a bit, then stick around 2-300rpm above normal. Seems like it's trying to idle down, but for some reason can't.
. Off-idle performance is not impacted, and even when it does it's weird idle thing, it doesn't misfire.
My first thought was a vacuum leak. I used carb cleaner to hunt around for a leak and couldn't find one. My second thought was that since oil pressure reads low on the factor gauge, maybe a weak timing chain tensioner was letting slack in the chain cause the timing to wander around. I pulled the valve cover, and as far as I can tell, everything looks ok down there. I did order a real oil pressure gauge to verify pressure, should have that installed in a few days. Timing is dead on, I replaced the TPS with OEM Toyota a couple years ago, injectors are from 22RE Performance...
Any ideas?
The truck always fires right up, hot or cold, and runs great. It usually idles, both hot and cold, steadily at 850rpm. It's never gone into a high idle when cold, which may be a separate issue. Occasionally, throughout the past couple years, usually when it's raining or very humid, it will idle about 2-300rpm higher than normal. However recently, when coming off throttle, the idle will bounce a bit, then stick around 2-300rpm above normal. Seems like it's trying to idle down, but for some reason can't.
My first thought was a vacuum leak. I used carb cleaner to hunt around for a leak and couldn't find one. My second thought was that since oil pressure reads low on the factor gauge, maybe a weak timing chain tensioner was letting slack in the chain cause the timing to wander around. I pulled the valve cover, and as far as I can tell, everything looks ok down there. I did order a real oil pressure gauge to verify pressure, should have that installed in a few days. Timing is dead on, I replaced the TPS with OEM Toyota a couple years ago, injectors are from 22RE Performance...
Any ideas?
May 13, 2025 | 03:15 PM
#3
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Joined: Oct 2011
Posts: 2,724
Likes: 342
From: Denver CO
Give a search on “idle surge” lots of things can cause it. I still have a surging problem when my A/C is on and the brake is pressed until fully warm…..I gave up years ago on troubleshooting cause it’s only for a minute. Maybe one day I’ll stumble on a fix
Last edited by Discombobulated; May 14, 2025 at 06:32 PM.
May 14, 2025 | 04:20 PM
#4
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Joined: Jun 2011
Posts: 1,699
Likes: 75
so if you tap the gas pedal, it doesn't stop the surging? trying to rule out a mechanical linkage problem, but that's probably not it.
generally with these engines you go in there and replace all of the vacuum lines and that flexible intake manifold tube that attaches to the throttle body, because it can crack and leak at the folds, not easily visible.
has the egr valve been cleaned out?
generally with these engines you go in there and replace all of the vacuum lines and that flexible intake manifold tube that attaches to the throttle body, because it can crack and leak at the folds, not easily visible.
has the egr valve been cleaned out?
May 14, 2025 | 04:44 PM
#5
I had a small vacuum leak at the idle screw because the o-ring had dried out and cracked. Took a bit to find but that helped stabilize my idle issues I was having at one point
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