Ditch Doc

Hi everyone!

I have a 1993 4x4 Yota pickup. She has a 22RE that was rebuilt about 12k ago. It has always taken forever to idle down from a cold start, but lately it has started surging as well. The surging starts about a minute after startup and doesn't stop until I've driven for a few minutes. It will also start surging occasionally at stop lights.

When the issue began, it was only when my foot was on the brake, so I was thinking a vacuum leak. With it now doing it on startup, I'm leaning more toward the IACV. It will begin surging around 2000 rpm, then drop to 1000 rpm, still surging when I hit the brake now... Maybe IACV and a leak as well??

I've searched for a while on this but was unable to find anything specific. I don't mind replacing the part, but I want to make sure I'm on the right track. Looking for suggestions and advice. Also, I'll post a video of I below.

Thanks!

AKHeathen

when you say "just about stallin out" it hasn't reached idle yet. idle should be 800rpm..... test and set the tps, and check other vsv's (the iacv is one of the many vsv's, iirc) one could be leaking, like for the ac, and giving vacuum flow full-time. you could turn on the ac and see if it affects it.

mikesnyhere

My 92 pickup did this for a long time . I thought the same as you a vacum leak . What mine turned out to be was a coolant passage in the tps housing was full of crud . Once it was cleaned the truck ran normal again . You might be able to find a mechanical drawing to see what I mean . It effects an air bypass valve that's thermostaticly controlled. Good luck .

Ditch Doc

Figured it out. It turned out to be the same issue that occurred years ago but I had forgotten about....

When the coolant level runs low, the temp gauge will still read normal even though the truck is still on the verge of overheating. The only indication will be the engine will start surging.

The last time this happened, it was found by chance when I blew out a main seal while driving through Boone, NC after picking up a new welder. The local Toyota mechanic noticed that the engine started surging after the repair and just happened to know about the coolant-gauge issue. Problem solved.

The radiator was changed out with the engine rebuild last year. I had long forgotten about the previous surging issue, but it all came back to me when it overheated last week when my wife was driving. I added coolant and found that the new radiator had developed a leak. Luckily, there was no obvious damage and the radiator is under warranty.

Thanks Heathen and Mike for the advice. Figured I'd post this follow up in case anyone else has a similar issue.