Got the codes! #22 (tps sensor signal voltage low) and #35 (idle air control sensor circuit fault.
If the TPS and IAC wiring look OK replace both parts. The TPS is a primary input for shifting and the IAC is the computer’s throttle. If it runs better when those are replaced flush the radiator and service the transmission.
I don’t see any exposed wires. Are the TPS and IAC parts that I can replace myself?
Both parts are easily accessed under the air filter and relatively simple to replace. I don’t know how experienced you are or how well equipped your tool box is, though. A god phillip head screw driver will remove the TPS and when installing the new one the slot and tang must be lined up. The IAC has a 32mm hex and once loosened can be removed by hand and the new one installed, hand tightened and then snugged tight with the wrench. If you replace the parts the engine will be somewhat balky when restarted and it will take a minute of so for the computer to recalculate the input from the new pieces. If you start the engine with the air filter off and the intake air sensor is in the filter housing the engine will run somewhat rich. but I believe your air temp sensor is in the manifold.
I’ve identified the TPS and will try replacing it on Sunday. The IAC I’m a little doubtful about. I found a couple of videos on replacing IACs but not my specific vehicle. Is the IAC the big brassy hex bolt sticking out from beneath the air filter? Facing the engine, it’s on the left side (pretty close to the TPS).
I have to say maury, you don t seem surly at all…
When standing at the front bumper looking over the throttle body the IAC is at about the 2:00 position and if you can turn it 1/4 turn outward with a wrench it should easily unscrew with finger pressure. Installing a new one requires no adjustment but it is advisable to spray a carburetor cleaner down the key hole shaped opening that is the air input for the IAC before installing the new one.
And I came from a long line of surly individuals. In fact I am the reigning surliest in the family at this time. We are an under appreciated asset.
I’m the epitome of humble. I bought a 1993 S-10 with a rebuilt engine two years ago for $2000 and I feel lucky. But there are problems, and I’m trying to sort them out and I can’t thank you enough for your helpful advice. That’s easy enough to type, but I’m not a wealthy guy so anything that I can learn to fix on my own is very appreciated and I hope I’ve said that enough.
Thanks!
I replaced the TPS, but not the IAC yet. I started the engine and the idle was super high. I waited a few minutes with the engine running, and it seemed to calm down a little, but not much. I drove it around the block and now the check engine light stays on and the gear jerking between 1st and 2nd is still happening. I disconnected the battery and let the codes clear out. Started the engine again. Same rich idle and check engine light (plus a new one “Check Gages”). I check the codes again, getting the #22 code for the TPS again, but nothing for the IAC this time. Replacing the TPS seems to have made an intermittent problem a constant one. Unless my truck is just in a bad mood today.
I’m reading a lot of similar symptoms on other sites and the possibility of replacing the shift solenoids comes up a lot (especially with the gears jerking between 1st and 2nd). Whaddya think?
Change out the IAC and see how it runs.
First things first!!!
Then you can tackle the shifting problem when you have the engine running smooth.
Yosemite
Okay, I replaced the IAC. I even tried to clean the throttle body up a bit, but there were too many things attached to it for me to feel comfortable disconnecting, so I just cleaned up what I could get to. Put everything back together, start er up and now it’s idling so high it’s kinda scary plus there’s a high-pitched whine along with it now. I tried to let it run for a minute (someone here told me that it would run crazy for a minute until the computer had time to adjust) but I was terrified of being horribly burned in a gas explosion.
I went back out and cleared the computer codes. Start it up, same really high idle and whine. I let it go for about a minute and a half. It lowered a LITTLE after a few seconds, then came back up. It’s so much worse now, since I replaced both parts. It seemed so simple to unplug the old TPS (and IAC) and plug the new one in, but could I have done it wrong? When I lifted the air filter housing up and was trying to get to the bolts for the throttle, I lifted off a metal cylinder to get to the bolts and noticed that the seal all around the bottom of the cylinder was chipped and dried out. I used throttle cleaner and cleaned it off. Do I need to get a replacement seal?
Kinda sounds like you have an air leak somewhere in the intake piping.
First, a fast idle is usually the result of a vacuum leak on a MAP controlled EFI system. Was this the cylinder that you removed?
If so replacing the gasket might reduce the idle speed.
Look around for vacuum hoses that aren’t properly connected also.
This is the metal cylinder I mentioned. I don’t know if you can see, but there are definite gaps along the bottom.
try spraying cleaner into the hole where the iac enterd also. maybe a toothbrush or bottle brush too.
definitely may be air leak or vacuum rather, causing the whine youheard.
did you replace the o-rings on the iac and tps? they should have had one on them or around the holes from which they were removed
I did clean the IAC hole but I didn’t replace the o-ring on the tps. I just now pulled the tps back off and put the old o-ring on it. When I went to put it back on, it wouldn’t slide straight on like it did the first time. I had to turn it (out of screw hole alignment), slide it on and then turn it back to screw hole alignment. I’m clearing the computer (again) now and will crank it up in a minute.
Ok it didn’t make any difference.