Island_Yota

Have a problem with my idle/throttle, I don't have a tach but it's sticking at around 1500rpm, does it between gears etc. If I tap the throttle usually it will back off to 1000ish, but sometimes it will surge up and down between 750-1000. I was thinking it was the dashpot sticking until it started surging, I checked the dashpot anyway and it seems to stick a little bit. Normally it has a fairly low idle, around 650rpm id guess.

Sound like the TPS?

abecedarian

sounds like the return spring or cable are sticking.

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 close and rpms drop to normal. 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.

mightymouse

iTrader: (6)

check out this thread! https://www.yotatech.com/forums/f116...ensive-199356/

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.

thedanned

Writ like a true Doctor!
Good job on the fix!

TerraXpeditions

Sounds like my experience last night. Exact same situation and results.

RustBucket

iTrader: (1)

Interesting about the throttle cable. Will have to check that out too.

PETDOC

After cable lubrication my 4Runner ran great for 2 days, then the cable began sticking again. Initially would stick at 1500-2000 rpms for a second then spontaneously drop to normal. While researching the cost of a new accelerator cable I hit on several threads where people with 22 RE's had experienced the exact same problem. When there was follow up all continued to fail despite WD 40, lubrication, etc... Because I intend on keeping my 4Runner I opted for a new cable. Best price I could find was http://www.toyotapartszone.com/ for $71 plus shipping. While there I picked up a bunch of other small Toyota "only" parts.
If anyone has a better (i.e., less expensive) source of Toyota "only" parts I would love to have a link.

RustBucket

iTrader: (1)

Not trying to hijack but my problem seems to be identical to island yota's...

I took another hard look at the throttle sticking situation on my 4Runner. I am now convinced that the cable is not sticking and the mechanism is working properly. I think there is some sort of vacuum issue that is holding the throttle plate open. I upgraded the return spring (the extension one on the side, not the torsion spring) to a slightly stiffer one with no real benefit.

The sticking is only apparent when the engine is running. When the engine is off the throttle doesn't stick.

The RPMs tend to remain constant when the clutch is pushed in and the throttle is up. So, say you're revving up in 3rd gear to 2500, let off the gas, push in the clutch, wait, and the RPMs will not drop. But if I am in gear and slow down to a near-stop in gear, basically dragging the RPMs down to idle speed, the engine will then remain near idle. What is going on??

TerraXpeditions

Mine was doing similar, on occasion it would bump back up.

Have you tried the cleaning and lubing method?

RustBucket

iTrader: (1)

Yeah, I removed the TB and cleaned it very thoroughly. I also advanced the throttle stop screw to prevent the throttle plate from wedging into the aluminum casting. I cleaned and lubed the pivots and dashpot as well. When the engine is off the throttle mechanism action is excellent and it does not stick.

mightymouse

iTrader: (6)

did you check your MAF? I had a similar problem last year and that was the problem. I think 4crawler has a write up on how to test it and see if it's working properly.

RustBucket

iTrader: (1)

I haven't checked the MAF. Probably a good thing to do, but I'm not sure how that would cause the throttle plate to stick when the engine is running.

RustBucket

iTrader: (1)

Holy crap! It was the dashpot all along! I removed the setscrew that hits the dashpot piston and the symptoms are gone. Must have had some junk in the bottom of the piston.

Griswald

I know it's been a few years...BUT

Ive been having this idle issue for awhile.
I just put in a new engine...we did our best to fix the high idle-cleaned throttle body, cable...etc
but now it's coming back about a week later...

It usually happens when I rev it slightly, like at stop lights after short spurts, or when I'm parking, backing up, etc, it likes to stick in the 1200+ range.
If I come to a stop light and let the idle go down as low as I can go before pressing the clutch, it likes to jump up to 1200...
However, If I'm cruising along in 2nd gear, and hold the RPMs at 2300+, then release, it usually drops right down to where it should be.

ONLY does this in the warm weather!
Which leads me to believe its gotta be the (old and worn out) cable expanding in the heat against the (old and worn out) sheath.
I'm going to replace the throttle cable.
Hoping that does it!

Griswald

forget the throttle cable. I did exactly this ^^^^ and it seems to have fixed the problem.
Idles right at 900 every time. 950-1000 w the A/C.