High Idle

So today i realized a new problem with my s10, its a 95 4.3 4 wd manual . I started my truck this morning and it had the normal idling sound, but i came back outside a few minutes later and it sounded like it was idling really high, so i drove it to school and everytime i would shift gears, it would just keep idling really high, has anyone else had this problem before?, my friends does this sometime, and he said it just happens every now and than. Φ if anyone can relate to this problem or explain to me what might be going on, i would appreciate it. ÆΦΓ :2cents:

Is that fuel injected or throttle body?

its the vortec, the first year of vortec, im pretty sure its fuel injected

yeah it is
hmmmmm i have no idea...sorry...if i think of something ill let you know.

alright i appreciate that, i just keep trying to think what it could be, it goes away after a while, like after 5 minutes its back to normal, i dont know if a fuel filter is clogged or maybe some other filter somewhere is malfunctioning. Im also thinking maybe my injectors are clogged, ill try cleaning them tonight and ill post you later

yeah if its not the injectors try the filter and yea keep me posted

throttle body is fuel injected.

Any vacuum leaks?

yeah...but its different than just fuel injection.

Yeah its a different METHOD but its still fuel injected

no vaccum leaks or anything, it all checked out fine, i think i figured out what the problem is though ive noticed that when it idles high its usually when the weather varies from hot to cold one day to the other. The problem i think is that the fuel is made richer to allow it to warm up, and in a way the truck is confused does this make any sense to anyone?

I came across this earlier when looking for other problems:

This answer is from: http://www.weberchevrolet.com/tech.htm

Question:
95 Chevy S-10 2.2L 4Cyl.
My truck has been running fine, but this morning I went to start it to go to work, and as soon as the engine went on, the RPM's went up 4500RPM's and stayed there. They have not dropped from there. I am do not have a clue why it just did that, but it was running fine yesterday. Need help.

Answer:
With the elevated temperatures we have been experiencing, ECM's and PCM's have been dropping like flies. Under the dash, on the right side this device is about the size of a small cigar box. If you can remove the two small screws holding it in place, there should be enough wiring to allow it to drop down. Now... ( this will not sound very technical ) taking a open hand, slap the side of the box one or two times, with the engine running. If it's what I suspect, the rpm's should drop. Circuit boards in vehicles are exposed to extremes, hot, cold, vibrations, you name it. After awhile the just give up the ghost. If this corrects the condition, its time to get a new ECM/PCM. I hope this helps.

isn't there an idle throttle positioning sensor on this vehicle?

The TPS or throttle position sensor is likely the problem. I wouldn't reccomend slapping the bottom of the ECM. I had to replace the TPS in my truck(94' 4.3 throttle bottle) and it fixed the problem. TPSs can be problems in many makes and models of vehicles.

Hehe, don't know why you brought this thread up from 4 months ago but.....

It is the IAC valve needs to be sprayed with carb cleaner, scrubbed with a toothbrush, rinse with the cleaner again and reinstalled.

it could be your intake gasget I had that trouble be for

I have the same problem. Mine occurs when it is damp and cold outside like below 60 degrees. It will idle high and exhaust will even turn black occasionnally because of really rich mixture. When it happens it usually fouls my o2 sensor. Makes it a real pain to drive in the snow. Besides it keeps stalling too from the rich mixture. Good luck pinning it down. Let me know if you do (89 S-15 4.3 TBI)

Have you timed your engine lately?

What you have could be a coolant temp sensor going bad.
If the signal sent from the coolant temp sensor shows that it very cold(default mode when bad) the ecm thinks it -40 and ups the idle.
A quick scan with a scan tool will pick that up fast.
Or remove the connector off of the sensor (up by the thermostat) and look at the connector wires does it look green or rusted if so clean them. Also you can use a jumper wire across the connector to fool the ecm that its hot and check for any rpm changes.
I just did that to the guy next doors 1995 4.3 was doing the same thing.
Fireplug

It will throw a cold if it was showing temperature problems.

P0117

Sorry M8
But they dont always throw a code. NOT if the sensor is still in it known working range but on its outer limits.
1995 high Idle problems where and are caused by
1. AIS/AIC Moter Automotic Idle speed/ Control on the throttle body. Remove it and clean it and also clean the throttle body with carb cleaner. The first restart might be hard to do it you use to much carb cleaner but that ok.
2nd Vacuum leak .anywhere in the system
3RD. Coolant temp sensor going out of range will cause a high idle, black smoke from exhaust, seen so many of this type and the AIC / AIS Motor dirty

my key board skills suck
lol
Fireplug

Were you saying IAC?

DAM DISLEXIC (spelling sucks too)
Yes IAC also sometimes called AIS in the aftermarket world.
ITs get harder when your old you are thinking 1 thing and typing something else and when you read it before you post it your mind tricks you . lol

BlazerLT
Does your scan tool let you get into the EGR system on the 4.3 and cycle the 3 EGR plungers.
The GM tech tool we had to do that on all the 4.3 s-10 trucks. Also if I remember right there was a recall (not told to the public) on the EGR Valve on the S-10 , Blazer .
We changed about a billion of them.
We had a bunch that would not set a mil light and just give a rough idle or it would set the mil with a random missfire code.
You all need to take your VIN number to a GM dealer and have them check to see if any recalls need done to the EGR system.
Fireplug

No, my tool does not allow for EGR plunger overrides.

I think the warranty was with the replacement EGR valves which were warrantied for longer periods of time due to their failure rates.

Too bad people can't just clean and reinstall them instead of having the dealer replace them all the time.