4banginRunner

I've searched with no successful results.

Vehicle:
1987 4Runner, 22RE, 5spd swapped

Problem:
Will start and idle fine, after it warms up, it will not hold an idle. Idle drops to 500 rpms or less, 9 times out of 10, it will stall. When driving in 2nd gear, around 1500 rpms, i can stab the gas and it fells like the brake is on until about 2000 rpms where it accelerates like a bat out of hell (nitrous type thing).

Just replaced the Coolant Temp Sensor, cleaned the TB a bit and it did nothing but improve pre-warm-up idle.

I've read alot of possible problems. Just wondering what I should go "waste" money on next to try.

abecedarian

Check for vacuum leaks and check the duct between the air filter and throttle body for any cracks, etc. What rpm does it idle at when cold?

4banginRunner

Vacuum lines seem good.
Would a gap in the intake ducting cause this only after warm-up?
Cold it idles around 800 Rpm

4banginRunner

Just jumped E1 / TE1 no codes

86Crawler

try checking your timing. Mine used to do that and it was that my timing was to far advanced

abecedarian

yes, a gap in the inake could do it since there would be air getting into the engine that wouldn't go through the afm. The ecu makes the fuel mix rich during warm up and this could cause issues with it warm as the mix leans out.
the 800 rpm cold idle suggests either a leak in the duct, or the idle is set wrong. you should be about 750 rpm warmed up. my 88 idles about 1000-1100 on a cold start ~50F, my 91 idles about 1100 also when cold, then both settle to 750-800 when warmed up.
as mentioned, the timing being could also cause similar symptoms
a low idle could also cause the timing to be off.

4banginRunner

I'll check on the intake duct, I used a piece of heater duct from my old '82 pickup when I did my batt/intake swap, so it could defiantly be the culprit.

Also, how would timing be affected? This problem happened pretty much over night. The engine sounds normal when it does idle normal, so I doubt the chain went and the distributer hasn't been touched since I put new plugs, wires, cap and rotor on in January. J/w, since i don't really know that much about timing.

4banginRunner

Just changed the intake ducting from hard plastic heater duct to a 90* Jeep intake ducting....no change

4banginRunner

read the haynes manual and searched pirate

could possibly be the Auxiliary Air Valve?

how much of a bear is it to change?

4banginRunner

Fixed it ,picked up a TB w/TPS and air valve at the junkyard yesterday for $20. Cleaned the both, installed and it idled at 2100RPM!!! Played with the idle and got her back down to 750, runs good now. Just hope the problem doesn't work itself back.

DupermanDave

I'm having the same problem. Is it really necessary to fully replace the TPS and TB? I dont have a salvadge yard around here to pull one from.

Any other suggestions? Did it need cleaned, adjusted, modified?

4banginRunner

i'm pretty sure it was the TPS

i replaced both b/c, well the 4runner in the junkyard had um, and it was cheaper than buying new, $58.xx for a new TPS and $249.xx for a Air Valve

after putting the "new" TB on it runs a heck of alot smoother, probably b/c its cleaned so that helped to

DupermanDave

Hmm. Mine's pretty clean. When I did the head job a while back I cleaned it so well I could lick it. It was shiny. All of the carbon and dirt was gone. It went through a hot tank bath and then was touched up with carb cleaner.

Mine's idling really bad now. Didn't do it until I removed the air filter to clean it. So my issue may be something different.

4banginRunner

what type of air filter? AFM might be gummed up

Bigblock

Or broke the piping.
Bigblock

abecedarian

how to fix, Bigblock?

DupermanDave

Im using a K&N filter. I cleaned the AFM because I thought it might be dirty and gummed up as well. Still no change. I'll look into getting a new TB and TPS, though. I just have to find a junkyard around here.

DupermanDave

I pulled the cable from the TPS and my truck seems to idle better than when it's plugged in. My gas mileage dropped like a rock, but this points me in the proper direction.

Now that I know it's the TPS, should I just replace it or is there any tweaking I can do? I see two screws holding it in place and it seems adjustable. I've already read that TPS guide and it completely loses me with it's instructions. I have an OHM meter (just got it today) and I'm going to pull the sensor to test/replace it.

abecedarian

if you read the 4Crawler directions, testing the TPS requires it to be installed on the throttle body.

4banginRunner

x2 needs to be on the TB

http://personal.utulsa.edu/~nathan-b...34throttle.pdf