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High idle?

Tiny
LOWX2
  • MEMBER
  • 7 POSTS
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.
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Wednesday, January 20th, 2021 AT 7:29 PM (Merged)
Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
Yes, it could. You should at least get a code 12?
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Wednesday, January 20th, 2021 AT 7:29 PM (Merged)
Tiny
LOWX2
  • MEMBER
  • 7 POSTS
Ok. No codes other than 12. Where might this wire go to? I found nothing of it in my haynes manual.
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Wednesday, January 20th, 2021 AT 7:29 PM (Merged)
Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
If it is on the back of engine, may just attach to the firewall?
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Wednesday, January 20th, 2021 AT 7:29 PM (Merged)
Tiny
MICHAEL26
  • MEMBER
  • 7 POSTS
  • 1993 CHEVROLET S-10
  • 100,000 MILES
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?
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Wednesday, January 20th, 2021 AT 7:29 PM (Merged)
Tiny
LOWX2
  • MEMBER
  • 7 POSTS
I hooked up a wire from the block to the firewall. I will post a reply later as to how I made out.
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Wednesday, January 20th, 2021 AT 7:29 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,755 POSTS
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.
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Wednesday, January 20th, 2021 AT 7:29 PM (Merged)
Tiny
LOWX2
  • MEMBER
  • 7 POSTS
Jump started the blazer, same issues. Took the battery to get charged.
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Wednesday, January 20th, 2021 AT 7:29 PM (Merged)
Tiny
MICHAEL26
  • MEMBER
  • 7 POSTS
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
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Wednesday, January 20th, 2021 AT 7:29 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,755 POSTS
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.
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Wednesday, January 20th, 2021 AT 7:29 PM (Merged)
Tiny
JNYBOB
  • MEMBER
  • 1 POST
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!
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Wednesday, January 20th, 2021 AT 7:29 PM (Merged)
Tiny
MICHAEL26
  • MEMBER
  • 7 POSTS
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?
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Wednesday, January 20th, 2021 AT 7:29 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,755 POSTS
No, the IAC wouldn't affect that. Check the linkage to the transmission.
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Wednesday, January 20th, 2021 AT 7:29 PM (Merged)
Tiny
NATY RAY
  • MEMBER
  • 1 POST
  • 1992 CHEVROLET S-10
  • 220,000 MILES
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.
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Wednesday, January 20th, 2021 AT 7:30 PM (Merged)
Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
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.
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Wednesday, January 20th, 2021 AT 7:30 PM (Merged)
Tiny
PSYCH
  • MEMBER
  • 1 POST
  • 1991 CHEVROLET S-10
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 274,000 MILES
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.
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Wednesday, January 20th, 2021 AT 7:31 PM (Merged)
Tiny
MONTICELLOROB
  • MEMBER
  • 4 POSTS
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?
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Wednesday, January 20th, 2021 AT 7:31 PM (Merged)
Tiny
NAP
  • MEMBER
  • 2 POSTS
  • 1986 CHEVROLET S-10
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 170,000 MILES
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.
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Wednesday, January 20th, 2021 AT 7:32 PM (Merged)
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Clean out the idle air control valve and also look for vacuum leak-start here
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Wednesday, January 20th, 2021 AT 7:32 PM (Merged)
Tiny
NAP
  • MEMBER
  • 2 POSTS
Thank you very much, I will check that out right away.
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Wednesday, January 20th, 2021 AT 7:32 PM (Merged)

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