teahou

Hello. I just bought a 94 4wd pickup, 22RE and it has a high idle, all the time (cold, hot, makes no diff). I am wondering if some can identify the part I have pictured here. It is attached to the throttle body, and the throttle linkage sits on the pintle.

I am wondering if this part is adjustable, because it seems to be holding the throttle plate open, thus the constant high idle.

Any hints would be great, thank you.

RustBucket

iTrader: (1)

That's the dashpot. It's a damper for the throttle plate so that when your foot comes off the gas, the plate doesn't snap back closed. Has something to do with emissions, and probably helps keep the throttle plate from wearing out.

In your second picture, look directly above the V in the left hand arrow you drew. There's a little set screw and a jam nut. Try loosening the nut, backing out the set screw a few turns, and then tightening the jam nut back down. The set screw contacts the dashpot plunger, so backing it out will make it contact the dashpot later.

Also, it's possible that the dashpot has gotten plugged. I believe they are expensive, so you might look in a junkyard or ask around on this forum. In the meantime, you could probably get away with simply removing the set screw and running sans-dashpot for a while. Shouldn't make a big difference.

Welcome to YT, by the way!!

blue_CA_yota

My Haynes manual it says it is for emissions, but also to prevent back-firing.

Junkers88

It's called a dash pot (like others here have said). It prevents the throttle from "slamming shut" when you get of the accelerator to shift, also helps keep the rpms up for a second or two between shifts so it will help on the highway to maintain speed. It does get clogged over time. There should be a small hose attached to the back end of it with a small "filter" on it, the filter gets full of stuff after a while. My advice? Pull it off and see if the problem persists. You can eliminate it by adjusting the set screw that RustBucket mentioned. I eliminated mine years ago since it was easier than finding a new one. No issues that I can report other than an instant drop in rpms when I get off the skinny pedal to shift.

jbtvt

Yeah, good luck finding a new one. I had to buy and entire used TB for ~$90 when I melted my dashpot years ago ("minor" engine fire) since no one anywhere could sell me just the DP. Definitely affects idle. My 3.0 wouldn't stay running without the set screw cranked way out and still idled inconsistently after that even. Looks like you've got plenty of adjustment left though.

teahou

First of all, thank you all for your responses and the welcome. I upgraded from an 85 Nissan pickup to this 94 Toyota and I am loving it.

I sprayed the &*@#^ out of the dp with some carb cleaner and it moves a little easier now, though I have not touched the adjusting screw yet because i want to investigate all other avenues of my high idle first.

I checked the ign timing and it is right at 5 btdc. I have read that many people have it set to 10, but the repair manual I have says 5, so I think I will leave it there.

Any other ideas on what would cause a constant high idle? I was thinking of taking the TB and IAC valve apart, to clean them out. The IAC looks different from what I am used to, it does not seem to be the pintle type, with a shaft that moves in and out, so any tips on what to look for when cleaning that?

RustBucket

iTrader: (1)

There's an idle adjustment screw on the top of the TB as well.

corax

Might want to check out this thread for some ideas: https://www.yotatech.com/forums/f116...-screw-201949/

teahou

That post is wicked cool. I had noticed my temp seems low, per the dash gauge, so i am going to check the thermostat first, then go from there. I just got this truck a couple days ago, and after some of the things I have seen so far, I wouldn't be suprised if the thermostat has rusted away.

4Crawler

iTrader: (3)

Dash pot repair (clean/lube) and adjustment:
- http://www.4crawler.com/4x4/CheapTri....shtml#Dashpot

combatcarl

https://www.yotatech.com/forums/f116...engine-220127/

I just pulled mine off. No amount of futzing with it would help it, and a new one is way too much.
Too be clear, the initial post was a 3.0. but should be same or very similar to yours.

teahou

All hail the Toyota gods! I found my high idle problem, it was the thermostat. My guess is it was stuck open, because the rig never fully heated up. I replaced it then freaked out cause it started running like heck, until I reinstalled the vacuum hoses I had removed. Took it for a spin, and after a couple minutes, the gauge went up to normal range and the idle came down to a normal level.

I've never had a rig with an IAC that ran off temp, so thank you all for your suggestions, and special thanks to corax for that link to the info about the thermostat.