bryontro

Has anyone had any experience with this type of problem? 1992 3.0 V-6 that stumbles and hesitates after warm-up only.

1.When cold (approx 10 minutes after first start) it runs beautiful, no problems.

2.Once the temp needle starts to climb the truck starts to stumble and hesitate.

3.Acceleration is unresponsive compared to when cold. Steady state throttle is fine.

4.Just checked plugs today. All 6 are pearl white (looks like it is burning lean)

5.Took a look at the oxygen sensor. It “looks” to be original and a heated type. Was thinking that it could be the problem since cold temp “open loop” runs great. Just a guess though.

6.The plugs and wires have been changed a couple of months ago with no improvement.

7.Also had the injectors cleaned on the vehicle with the type that runs the engine with the can of cleaner (fuel pump disabled). The truck ran for 30 minutes on that can of cleaner. Truck was a bit smoother but the problem is still there.

8. I have not replaced the fuel filter yet but full throttle is smooth just not all there and idle is perfect hot or cold.

I saw a thread where a guy had the same exact issues with a 22RE and he took apart his TPS and cleaned it. He said that that was the fix. I just wonder why it doesn’t do it when the truck is cold. Just want a couple more points of view before I tear apart my TPS. Also noticed that my TPS seems to be connected to a vacuum actuator, what is the deal with that? What is in my head is that the cold start injector is maybe masking the problem during the first couple of minutes that the truck is running. By the plug though the truck is running leaner than I am used to seeing on other cars/trucks. Any help would be great!

Fink

I did have that problem a little while ago but some new Bosch Plugs fixed it.

I do have this problem though however, sounds similar...here is the link:

https://www.yotatech.com/forums/show...threadid=14525

Read that, another problem I am having is when I first start it.

But my rig is at the shop now, when I get it back if the problem is fixed I will let you know what they found. Hope that helps ya, if you have anymore questions feel free to PM me anytime!

AgRunner06

Here is a website about the TPS.

I would change the fuel filter and the O2 first and see if that clears up the problem. The O2 shouldn't make it hesitate, but you shouldn't be running lean.

Good Luck

bryontro

It was the TPS. Check out this thread for what I did.
https://www.yotatech.com/forums/show...threadid=12860

Sac State

Bryontro: How do you like your Scorpions?

rreed

I'm new to these Toyota vehicles so please go easy on me. Where is the TPS and what does it take to get it out of there? My GF has a '92 V6 that's occasionally hesitating--sometimes severely--at take-offs when the vehicle is warm. Souds like the same problem you're describing.

AgRunner06

It's on the side of the throttle body. If you go to the link that I posted above it will give you all the info you need.

Fink

Check the entire Throttle Body assembly...got the rig back from the shop yesterday, it was all gummed up and sticking everytime I hit the acclerator.

Get some carb cleaner and clean that SOB!!! Save you some money if you do it yourself!! I wish I had atleast TRIED!

Hope that helps!

rreed

Yeah I followed that lead after I posted. Next time I see her 4Runner I'll look it over. I hope the fix is as simple as that. The vehicle only has about 180K on it so maybe the TPS is a little gooey.

Thank you all very much for the help.

bryontro

I like them. They seem to perform pretty good and they are not loud on the street.

rreed

Okay so I tore into the TPS (god what a PITA to get it off there, taking the entire TB off and everything, three hours of tool-flinging, curse word spouting fun), or at least removed it foolishly expecting to be able to clean or do something otherwise useful. Aside from breaking the outside metal cover off, it's apparently a non user-servicable part. But it felt smooth through its range of motion. Testing w/ DVM showed consistent resistance. It didn't appear dirty anyway. As far as I can tell the part seems good. Oh, and if you mess w/ it at all, you WILL want to replace those lead/pewter insta-strip screws (thank goodness for vice grips) w/ some allen screws. From then you should be able to adjust it w/o having to fling so many tools and wake the neighbors w/ such profanity.

The TB itself only had a slight amount of black crud in it, not enough to warrant cleaning. And what the hell's with running a coolant line into/through the TB??? Only a foriegn car.

I did however calibrate it according to the TPS site mentioned in this thread. At least I think I did. I don't know what throttle stop bolt/screw dude was talking about, the only thing I could find on the TB the plate stops against is some kind of plunger thing on top. Not having the proper feeler guage w/ me last night I just set it @ 500 closed and left it at that. I'll call the GF today and ask her if it nearly got her killed pulling out into traffic again.

Thanks again all for the help.

bryontro

Make sure and apply vacuum to that diaphram. I took a hose and sucked on it. The stop is on the other side of the throttle body. I still have had good luck with mine so far. Don't know how long it will last though.

rreed

I pushed on it really hard to see if it would go back any and it didn't, for whatever that's worth.

After a long test drive that night of numerous starts and stops it didn't do it, and didn't do it all day yesterday. I'll check back with her later on to see if it's still having the problem.

rreed

Several days, or perhaps slightly more than a week later she said it hesitated again when trying to take off.

Any other ideas?

lsires

My truck (135k) hesitates after warmed as well. Sometimes when cold though.
Problem:
Occasionally when you are driving or just reving it will drop down to an idle. It does not stall. Sometimes it will drop down for a quarter of a second and jump back up to normal very frequently (a few times in 2 to 5 seconds) and sometimes it will only do it once every 10 seconds or once a day if at all. Sometimes it seems like it is more likely to occur when the turn signal is on, but this may be more a figment of my imagination. Typically it is fine for short trips. Rarely will it hesitate while cold.


I diagnosed the tps switch with a mitchel manual available at the public library and it needs some adjustment, I wouldn’t expect a mal-adjusted tps switch to create an intermittent problem like this though.

I am going to check out:

Replacing the fuel filter
Replacing a cracked dashpot cap (although this is more of an idle control I think, couldn’t hurt by being replaced)
Recalibrating the tps
Check for bare wires.

Any other suggestions?

winterunner

hi, I had the exact same problem on my 93 2.4L, I put a new tps in and nothing happened. It ran great when cold but after about 5 minutes it would idle really bad and acceleration was really sluggish until it hit 3500 rpm them it would kick. I brought in my truck to the muffler shop because it was running loud, and they said that it was loud because my o2 sensor had vibrated loose and blown out of the exhaust pipe. they put it back in and tightened it up and presto! It ran like new right away. I found myself speeding all over the place. Its been about a week and the engine light keeps coming on now. I think that the sensor was loose for a long time and may have been banged around and damaged. so I'm thinking of replacing it. It still acts up but only a fraction of what it once was.

I'll post my result after i inspect the sensor, but I would check out yours before messing with the tps, they're real easy to get to, but make sure the engine's cold... ouch.