CityOfTree

Hey Guys,

When sitting at stop lights my pickup's idle will fluctuate (bog down, then rev back up) and it goes through the cycle in about 2-3 seconds, bog down then rev back up again, and again, and again, until I release the brakes then it just idles a little high on its own.

Found one thread that mentioned the brake booster might be the problem, but it looks fine to my uneducated eyes. Checked all the vacuum lines I could find and they all look fine. I did just install a junkyard VSV to the EGR valve cause the one I had the vacuum nipple broke inside the hose, and it threw a code for the EGR, which the junkyard VSV got rid of. I know that my a/c idle pulley is bad too, which I will be replacing later today, but I dont think that would affect my idle this way at all.

Any suggestions would be appreciated, thanks!

Gamma_Hugo

https://www.yotatech.com/forums/f116...-surge-232831/

Gamma_Hugo

https://www.yotatech.com/forums/f116...urging-203185/

CityOfTree

Thanks I will try that this afternoon, in your video, my truck is doing the exact same thing almost!

CityOfTree

I cleaned out that valve I saw in the picture (linked thread above) with no change, it wasnt clogged at all, but I still have idle surge with the brakes applied

I cannot find the damn IACV in the FSM, anyone mind giving me a clue so I can clean that out?

Gamma_Hugo

https://www.yotatech.com/forums/f116/iac-valve-226680/

its the bottom piece connected to the throttle body. it has 2 small coolant hoses connected to it. once removed, make sure that you can blow air through those 2 little pipes on the IACV, if you cant then they are clogged and most likely is causing your isle surge

CityOfTree

Maybe a dumb question, but do I need to remove the TB? If so, I need to go get a new gasket as well...

Gamma_Hugo

yeah you do, its kinda difficult to remove it. i had to get new screws because i stripped the ones that connected the iacv to the tb. i didnt put a gasket to the tb, i just used black silicone and so far has been working great.
where in sac are you?

cody o

Are you running your a/c while this is happening? If it does this when your a/c is on, but not when it's off, then your idle and a/c fast idle are out of adjustment. The Toyota manual give a procedure to adjust them properly.

snobdds

All this misinformation on this thread. Sad.

Your idle is too high causing the surging idle between low and high. It worse when the brakes are applied because the computer cuts fuel to the injectors then a few seconds later put fuel back in the system. Just take a flat head screw driver and turn your idle screw down until it's about 750 RPM when the engine is warm.

FYI - If your IACV was clogged, then you would have no fast idle at inital warm up.

4Crawler

iTrader: (3)

X2 on too high an idle speed. Details below:
- http://www.4crawler.com/4x4/TLCA_Tru...ech.04.09.html

cody o

agreed. just make sure you set both idle adjustments.

snobdds

The AC has no bearing on what the idle is doing when the brakes are applied. If you set the idle on the throttle body to the correct RPM setting, then in turn it will correct the AC idle up to the correct setting. There is some fine tuning adjustment, however, not enough to make much difference whenthe brakes are applied.

This all assums he has AC, if not then the AC idle up is a mute point.

CityOfTree

Thanks for all the input!

Went out and got the gasket for the TB since I was going to clean the IACV, but on the way back from the parts store, it mysteriously started idling fine, WTF?!

I do have a/c and the idle was crap with no a/c on, had not tried it with the a/c....

cody o

I have to disagree (but I should have been more specific). The a/c fast idle needs adjustment if it throbs with the brakes applied and a/c on, but is fine with the a/c off.

If it throbs with the a/c off, then it's not the a/c fast idle. Wouldn't hurt to do them both at the same time though.

CityOfTree

Hugo was right, I finally took apart my TB and sure enough my IACV had one of the coolant ports clogged. Pulled back the spring loaded diaphram and blew out a chunk of crud, now my truck idles perfect again!

That idle screw was already in all the way so it was not possible to tighten it anymore

Thanks guys

blake.nemitz

mine did that and i had the wrong line going to the egr

Sixstring361

I have the same issue with my 88 runner 3vze. It's killing me to know what's going on with her. Ive had yotas all my life, but it was the 22re, this is my second v6. I bought it with a 91 runner 3.0 in it, auto trans. I swapped it to a 5 speed without too much difficulty. But the idle has been surging even with the auto in it. It idles right about 12-1300 and when I hit the brakes it surges from 1100-600 and up and down and up and down. --to try to fix the issue I put a booster from a 85 parts truck. Same issue. Any help?

xxxtreme22r

idle too high. put your idle at 750-800 where it belongs and I bet that surge goes away. Find out why your idle is high to begin with though, don't just assume it's the idle screw. A vac leak will cause a high idle as well I believe.

4Crawler

iTrader: (3)

"It idles right about 12-1300" <- That

See my earlier post.