high idle?

Hello,

Usually this is caused by a vacuum leak, and if the RPMs are that high, then a major one. Here is a link to a guide explaining how to track down vacuum leaks. Please pay special attention to the intake manifold portion of the guide.

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Please go through the guide and get back to us with what you find out.

Thanks,
Alex
2CarPros

Hello,

It could be the throttle valve is not shutting or sticking open, Clean and adjust it and check the throttle cable adjustment. There could also be a massive vacuum leak check the intake gaskets for vacuum leaks. Check the EGR valve for sticking open, Check the brake booster hose and all vacuum lines. Check the Idle Air Control motor pintle for carbon sticking and the throttle valve idle adjustment for tampering. Check the correct positive crankcase ventilation (PCV) valve, properly installed and proper operation of the PCV valve. Check for restricted air intake system. I'm attaching repair guides and component location below. Let us know if you more info.

https://www.2carpros.com/articles/engine-idles-too-high

https://www.2carpros.com/articles/idle-air-control-valve-service

Thank you
Loe T.

I just did the heads went to start it and at first backfired and would shut off. Checked the plugs which were new and three of four was fouled out and the fourth one looks untouched. Changed the coil pack and control module now my idle is 3,000 rpm's to 3,300 rpm's.

Good morning.

Are the plugs fouled with fuel or oil?

The high idle may be from a vacuum leak when you re assembled. Go over your work and make sure all the hoses are connected.

Make sure the throttle body plate is closing at idle as well. If the plate is partially open, it will give you this condition.

Roy

https://www.2carpros.com/articles/engine-backfires-while-running
https://www.2carpros.com/articles/engine-idles-too-high

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

They are fuel fouled do you by chance a simple vacuum hose diagram?

Diagram.

Check your injectors to see if they are delivering too much fuel.

Roy

How do I check them?

You need an injector tester to see the on time commanded by the ECM. You can rent a tester at a parts store to verify.

Roy

https://www.2carpros.com/articles/how-to-test-a-fuel-injector

I have a 2.2L 4-cyl. standard, 2 wheel drive. The idle is between 1000-1300 rpms. I have replaced the throttle position sensor and the idle air sensor. Also, the throttle body adjusting screw is backed out as far as it can go. Any ideas on what could be causing the idle to stay up this high(it should be about 750-800 rpm at idle)?

These trucks had a problem with the throttle body gasket blowing out. Please remove the unit to inspect.

These guides can help as well


https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

https://www.2carpros.com/articles/engine-idles-too-high

Please let us know if you need anything else to get the problem fixed.

Hello. I have a nasty high idle in my 95 chevy s10. I have replaced every single electronic component that would effect the idle. The weird thing is that when I unplug the idle air control valve from the computer, the truck doesn't idle high.

Any help would be appreciated. Thanks

Try cleaning the IACV out-don't work-look for a vacuum leak-also check the TPS

I have already done all of that and I still have a intermittent high idle.

just got a 94 chevy s10 it runs great but the idle is to high im not sure what it could be or where to start.

first thign to do is check for vaccum leaks.

check everything after the MAF sensor. if you dont find anything move onto checking for proper function of the pcv valve.

Engine Performance problem
1994 Chevy S-10 6 cyl Four Wheel Drive Automatic

i did a motor swap on my 94 s10 blazer. after completion, it had a high idle, around 1200 rpms. i drove it till the battery died from trying to start it. when i first put the battery in, it fired right up. As the week past, it wanted to turn the motor less and less, til it died altogether. recharged the battery, it did the same thing. i am at a loss right now. anything you could tell me so i can get this truck back in good working order would be greatfully appreciated.

cont>... also there was a ground wire of some sort that came from the back of the motor and went somewhere. on the donor motor and the original motor, the end that went somewhere were both missing the ring terminal. it was just the wire atteched to the motor.

Was the donor vehicle the same year--make --model and engine size? Sometimes you have to get the computer from the donor vehicle, if there is any difference. Any applicable mil codes. Can you communicate with the computer. You can check spark at the plugs and fuel pressure, if vehicle is hard to start.

Then, attach the wire to the chassis, if ground.

the donor motor was the same block, i think from a 92. all the plugs went to the same place, except on top of the a. c., which i removed altogether. as far as computer from the donor blazer, the truck was smashed after the motor was pulled.

You should be able to check mil codes? You use a jumper wire between the A & B terminals at the datalink connector, turn the key just till the dash lites come on, no further. The mil starts flashing, you count the flashes to get the codes. If no communication with computer, not sure what to tell you?

no codes. it did shoot a code when i first fired it up, but from the battery dieing, i am sure it was lost.
could the ground wire not being hooked up cause these kinds of problems? it is the bare wire the goes from the back of the motor to i have no clue where.

Yes, it could. You should at least get a code 12?

ok. no codes other than 12. where might this wire go to? i found nothing of it in my haynes manual.

If it is on the back of engine, may just attach to the firewall?

have replaced a v6 motor into chevy s10 ext cab. engine idling high now. tps, auto air sensor, and coolant sensor could affect it?? i was told could be my temp sensor. these sensors are the same sensors from old motor that i had tooken out, never had this problem til i replace the motor. I know tps controls the idle , and tells it when to shift gears, but when i go to unhook the temp sensor when engine running high it idles way down then back up to high. but doesnt start when sensor is unplugged. tps unhooked doesnt change anything. what could my problem be???

i hooked up a wire from the block to the firewall. i will post a reply later as to how i made out.

The idle air control valve takes care of the idle. check for vacuum leaks too. If this is the 4.3L, check the intake for leaks. It was a common problem.

jump started the blazer, same issues. took the battery to get charged.

I have checked every vaccum every hose is brand new connected good. have one more question on this, On the radiator .. why would my top hose collapse , block is full as well is the radiator is full of coolant. its hot but no coolant. engine never gets hot either. i have changed the thermostat new. I will check all these tomm and replace what u have suggested. and i will donate something for your help. its just so aggravating! thanks

Not a problem... The upper rad hose should have a spring inside of it to prevent that from happening. Are you sure the thermostat was installed in the correct direction? Also, is this the 4.3 and not the 2.8? As far as a vacuum leak, I understand all the new hoses are new, but the intakes on the 4.3 from back then had problems with leaks. As far as the IAC, remove it and clean it. Have a helper turn the key on and off. You should see the pintel move a little. What happens is on a fuel injected engine, the throttle plate closes completely when you are off the gas. However, the engine needs air to run. That is where the IAC comes in. The pintel valve at the end allows metered air to enter the intake based on what the computer tells it.

As far as donating, if you can great. If you can't, please don't worry about it. We are here to help. Regardless, let me know what you find.

LOWX2, The cable that is attached to the block, should be a ground. It should be flat and about an inch wide with no insulation, unless it had been replaced. Remove the cable from the block and clean both ends with a wire brush. Clean the block and the firewall where you will attach the cable with the wire brush. Attach the cable with good clean bolts and make sure the connections are tight. Give time for the ecm to reset itself. Let us know if this works. A bad or lose ground can cause many problems. Good luck!

what can cause the transmission to not shift until around 25mph and its not shifting into passing gear. Trans was fine before, could the IAC valve have anything to do with that?

No, the IAC wouldn't affect that. Check the linkage to the transmission.

When the truck is started the truck idles up and down eventually it will cut off if I don't give it gas. Even then it wants to choke out. If I sit still and let it run with my foot on the gas it will run fine for a while but when I'm at a stop light or stop sign it wants to choke down and cut off. The problem gets worse if I turn on the air conditioner.

Usually, with idle issues, I clean the throttle body and check idle air control system. You may also need to check egr and map sensor. The vehicle runs ok, going down the road?

Can you check applicable mil trouble codes? You should be able to check those codes, yourself. You use a jumper wire between the A & B terminals at the data link connector. Then, turn key just till the dash lites come on ,no further. The mil on the dash starts flashing, you count the flashes to get the codes. Your looking for two digit codes.

This is opposite of the usual question.
When my truck is started, it idles at normal speed for 5-15 minutes; after that, it suddenly revs up around 3500rpm. If I tap the gas pedal, the truck usually dies (not always). Then it is hard to start. Usually I have to let it sit for at least 15 minutes, then I go through the same routine when I start it.
I've had the truck sitting for the past year, but I did put Sta-bil in the gas and I used the truck 6 months ago and it ran great.
Where do I start?
Thanks.

My friend has 93 S10 V6. He said it ran fine until the hired help steam cleaned the engine. After that, gas had to be poured into the intake for it to crank, then it would idle very high. When the mass airflor sensor was disconnected, it would idle at normal speed but ran rough and acted as if it were running very rich. Also, with the mass airflow sensor disconnected, it would crank without being primed. Also, when running, if one of the two injectors was disconnected, it would idle down but idle rough.

I replaced the mass aiflow sensor. It no longer needs to be primed with gas to crank, however it still idles at a high rpm.

Any suggestions or solutions?

I have a 1986 s-10 pick up with a 2.8 liter and automatic transmission. why does the engine idle increase alot when i put this truck in gear? in neutral or park it seems to idle ok or at the right RPM. but as soon as i put it in any gear the RPM revs high. too high.

Clean out the idle air control valve and also look for vacuum leak-start here

thank you very much, i will check that out right away.