briholt

I'd like to clean up the dashpot (you can see the tear in the boot) and I just wanted to make sure that it should just pop off by unscrewing those two little screws right there (one by my finger, the other straight up in the shadow)...

myyota

Remove those screws and it will come off.

briholt

Sweet, Thanks!

StanBo

Have you found a replacement dashpot and if you did what was the cost? My idle gets lumpy at times and I take it that the dashpot is the culprit. Thanks!

shaeff

Dashpot shouldn't have any effect on your idle. All it does is stop the throttle plate from snapping shut 100% right away when you let off the accelerator. It's used to slowly close the throttle plate that last tiny bit in an effort to keep emissions down.

If you're having idle issues, look elsewhere.

shaeff

^LOL!

Also, even if the dashpot got frozen in any of it's operating range, it would cause the idle to be slightly higher, but not lumpy or cause missing by any means at all.

StanBo

Thanks for the heads up.

Do those come from Lumpy Potatoes?

Idle fluctuates 1500 to 1000 at times. Then goes away. Usually in the winter. I thought it would be the dashpot not allowing the throttle to return all the way back causing the extra rpms.

shaeff

If the dashpot sticks, it'll just be like your foot is ever so slightly touching the accelerator. It shouldn't cause surging. All the dash pot is, is like a small shock absorber for the throttle plate.

briholt

I haven't yet removed mine (busy this silly season) and I want to first get a few miles on her with the TPS disconnected to see if I get improvement there, first.

And, once I do remove the dashpot, I think you can take it apart some and clean it up. If I have to replace it, I have no idea the cost..

AKZEP69

after trying other fixes for same type of high idle issue - I adjusted timing, idle screw, clean throttle body - new throttle cable / return spring....removing and cleaning original dashpot - even scrounged one off a corolla that looks like the one in your picture.
Nothing worked.. autopart stores no help either ....
called dealership.. took a while b4 parts guy found in his book - the price
$166 + shipping, just for the part..
Installed and no issues since.

PETDOC

Had a similar problem in my '88 4Runner--idle would intermittently stick between 1500-2000 when I stopped at a light. If I popped the gas peddle it immediately returned to normal idle rpms. This went on for over a year before I tried to fix it. When controlling the throttle at the throttle body, I noticed if I allowed the throttle to return slowly the rpms would stick, but if I let it snap back the rpms were normal. Then when it stuck I noticed with light pressure I could get the throttle to drop to normal closure. I initially focused on Dashpot, but filter worked fine (blew on it both ways, easy one, difficult the other) and the rod seemed to work ok (lubed it with silicone spray). Then I did the simple first--I got some throttle body/choke cleaner safe for electrical sensors and a baby bottle brush. Parked the rear of the 4Runner on an incline so throttle body was pointing downhill, then cleaned out tons of tar-like residue from the throttle body. Idles perfectly again.

PETDOC

Oops! Fooled by randomness. My idle problem was not solved after all; just a temporary reprieve at the time I wrote the original reply. Subsequently I did finally discover and correct the problem.
To recount the problem-
1. Intermittently high, but steady idle (1500-2000 rpms) for over 2 years which resolved by popping the gas pedal.
2. Initially only in summertime, but had progressed to year round.
3. Discovered if the gas was released slowly problem occurred, but if released suddenly, no problem.
4. The throttle assembly could easily (i.e., light digital pressure) be returned to normal when high idle was present.
5. Dashpot ruled out by inspection and using flat bladed screwdriver to push rod going to dashpot diaphragm down during high idle with no effect on rpms.
6. Thorough cleaning of throttle body with throttle/choke cleaner--no effect (but lots of gunk).
Decided it had to be either:
1) weak throttle valve spring--but why not problem all the time?
2) dirty throttle valve rod--why didn't cleaning affect?
3) throttle cable hanging up--made sense with 320,000 miles, sheath may contain gunk increasing friction between cable and sheath, which could be exaggerated in summer by heat expanding metal cable. Fast release of throttle would overcome gunk friction; hence, normal operation when gas pedal popped.

Removed 2 bolts holding throttle cable sheath flange to firewall, and the cable from the throttle assembly. Attached cable lubrication tool to cable end. Sprayed in lubricant until draining at firewall. To my surprise it also drained from undiscovered crack in cable sheath at sharp bend before the flange. Reassembled, took for long drive with many stops--works fine now. I suspect a crack in the sheath allowed water in and the cable has begun to rust at that site. My current plan is to seal sheath with heat shrink and see if I can get another 20 years out of it.