I blew a headgasket due to electrolisis on my 89 4Runner w/22RE in it. I had the head rebuilt, put it all back together and it started right up. It ran smooth for about 3 or 4 seconds, then started running real rough, slowed way down and stalled. You can keep it running at a higher rpm and it's smooth, but it wont idle. I checked all the vacuum lines, can't find any vacuum leaks. Checked and rechecked the timing chain and proper rough timing.

I can't see any of the many sensors that aren't hooked up; they look fine. I had one run similar to this with a faulty MAF but cant find anything wrong there either. This Runner ran real good even after I blew the headgasket. I drive it into my shop to tear it down. It almost seems a timing problem, but it isn't. I'm stumped. Any ideas? Thanks

 

maybe your TPS is out of whack now and needs to be readjusted

 

It could just be the idle speed screw needs adjustment.

 

Re: TPS; I'll look at that again, but I didn't disturb anything on the manifold. I checked the idle adjustmment also. When I did the job I just removed the throttle body and ubnbolted the intake enough to lean it back out of the way. I unhooked a few sensors such as cold start and temp sensor plugs on the manifold. I took the egr off. Everything went back on pretty well. I'm no pro wrench, but this wasn't too big a job. Most of the sensor connections were unique to their sensor, and the vacuum connections are posted on the inside of the hood. I have rechecked all of these.

I just have to believe someone here has encountered this before. Thanks for the suggestions so far.

 

There are multiple grounds in that area.. Get them all bolted back up?

Check timing?

 

Well, re: grounds, I'm pretty sure I got them. There was one from the firewall to the head, and another ground on the passenger side to the block. There is also a metal bracket to the intake. Re: timing, I need it to run to accurately time it. It is close, and I have the jumper wire on it. It starts right up and you can keep it running at a relatively high rpm. Maybe 1500 or more. It sounds good at that rpm.

 

Are you sure you set the timing right?

It's possible you're a tooth off...

 

Recheck your valve adjustment

 

Thanks for the continuing replies. I am checking everything and still havent found the problem, Re: possible one tooth off; wow, I was meticulous about that. It runs real smooth at higher rpms. I don't think it would do that.
Re: adjust valves; did it twice; they'er right on .

What I'm doing next is ohming out each of the sensors. Dang WTH; I found the knock sensor doesn't have anything hooked to it. I can't even find the wire yet. Would that cause my problem? It looks kinda dirty, like it may have been unhooked for a while. What would be a symptom of a knock sensor that is not hooked up. BTW, I don't have any fault codes showing yet.

 

that sounds exactly like a problem I had, turned out to be a faulty tps sensor. Replaced, adjusted and perfect.

 

Most throttle position sensors "fail" between closed throttle and 15% open throttle. If you think about it that is the position where they spend the most time. They develop a sort of dead spot but at a different position can seem fine.

 

Well, you guys have my attention. I will ohm that sucker out as well. It just doesn't make sense for something like that to be the problem, since I haven't touched it, and it worked fine before I took the head off. I hope that's it; we'll see.

 

The best way to check for vac leaks isn't visual inspection - it's spraying them down with carb cleaner, etc. I'll bet it's either vacuum or timing.

 

Well, it was a vacuum leak. I thought it sounded like one, but I couldn't find it. Couldn't use brake cleaner or propane. because the engine only ran at a higher rpm anyway. I fond it by feel. Loose bolts back by the 'EGR. I thought I checked them. I feel stupid, but at least it idles now. Thanks for the help .