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Harry Steven Posted on Sep 03, 2012
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2500 HD chevrolet low idle problem

During the winter on start up will not hold 1200-1300 RPM, have to manually keep up idle until warm. Idle after warm between 250 RPM and 500RPM

1 Answer

Marvin

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  • Chevrolet Master 85,242 Answers
  • Posted on Sep 04, 2012
Marvin
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Engine stalling and rough run issue at low speeds

This problem is commonly caused by a dirty automatic idle speed control valve and throttle valve. Buy a can of throttle valve cleaner (do not use carburetor spray cleaner!) from NAPA or Carquest (made by CRC chemicals) and spray it into the air intake while the engine is running, use up about 1/2 the can, engine will try to stall hold the speed up, shut it down and let it soak for 30 minutes, restart and blow out the remaining fluid, shut it down and disconnect the negative battery cable for 5 Min's to reset the base idle control

5 Related Answers

Anonymous

  • 34 Answers
  • Posted on Nov 14, 2008

SOURCE: ENGINE STALLS DURING COLD STARTS.

Sounds like an IAC motor, If you look near the trottle body there is a long cylinder with two bolts holding it on, the only other suspect would be a vacuum leak. -Jared

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Anonymous

  • 3533 Answers
  • Posted on Jan 09, 2009

SOURCE: At startup my 94' F150 will oscillate from high to low idle

I had this problem once on an econoline van and it was the plantum gasket but before you change this check all the vacuum lines and get a digital volt meter and test the voltages on the mass air flow sensor and if you have to change the plantum gasket auto zone can print you out a diagram stating all you have to remove to replace it

Anonymous

  • 1 Answer
  • Posted on Mar 06, 2009

SOURCE: 98 Isuzu Trooper stalls on cold start, idle issues..

I had the same issue on my 99 Trooper.

It would usually start when completely cold, but idle around 2k RPM.
It would drive fine. But if I shut it down, ran into a store, and came back out, it would start but immediately idle.
Had to ride the gas a little to get it into gear.
The Check Engine light has been going on and off for 6 months or so.

I took this to my local trusted repair shop (no Isuzu dealers within 200 miles).
The diagnosed the light, and found that the Intake Gaskets were bad or leaking.
The idling problem was related to the car not being able to control the amount of air coming in.

They replaced the Intake gaskets by the next day, and I haven't had a problem since. And no more check engine light, which has been on half a year.

Here's some details from my bill:
(1) Intake Gasket set $107.95
Misc materials $21.00
2.1 hours of Labor

The total cost to me was $345.00, and I definately don't feel gipped.

emissionwiz

Marvin

  • 85242 Answers
  • Posted on Mar 11, 2009

SOURCE: car idles low, stalls after start

Common issue at the shop (i'm a ford technician), here is what I do to correct it.
Here is the most common cause of surges and stalls at stops and low erratic idle speed and rough idle, it is the idle speed control air-bypass valve and throttle valve (IAC for short), they get full of gunk over the miles and cause idle issues (stalls, low idle) like yours, Get a can of intake cleaner from any local parts store, not carb spray, intake cleaner, it is made by a company called CRC, remove the air intake hose to the engine, hold the idle high so the engine won't stall, then spray the can of cleaner into the intake while keeping the engine running, use at least 1/2 the can, shut down the engine and disconnect the battery for 5 minutes, then restart and complete a number of mixed driving cycles, town, freeway, stop and go etc., after a few days the problem will go away as the system will relearn to the clean intake.

Anonymous

  • 1509 Answers
  • Posted on Nov 02, 2009

SOURCE: rough idle then stalls

Vacume leak or bad idle motor. With the car in park and running with the hood open listen for leaks moving your hand around the different hoses looking for a change in the sounds that you hear. The idel motor also makes the car idel up to 1500 RPM or so right at start-up then idel down, If it doesn;t the idel motor is likly. Check engine light is on when running? Test for codes, Follow code test charts don't skip any steps!.

Testimonial: "Found the problem vacume leak like you said."

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0helpful
1answer

Engine idles up to 2500 and after 5 or 7 seconds, goes back down to 1200 rpm 2002 escort SOHC

Clean out the throttle body carefully and replace the auxilliary air idle valve. There is a resetting process for this valve so dont just fit and hope!
Check on Google or forums but i think ...when fitted you turn on ignition but dont start car , then put the accelerator pedal slowly to fully open, hold it for a min then release. start and drive car until warm and the recheck.
If the idle is high then settles it is not an air leak. It is something stuck that then releases which is only throttle flap or idle valve. It is always a goid idea to replace fuel, oil, air filters on normal service intervals.
Roger
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High idle

The throttle position sensor may be causing your issue----This sensor monitors the outside air temp.In the winter the throttle opens up far because th.e air temp is cold and vice versus
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Idles@2500 rpm until engine warms up

old post
all do, everyone. but. the devil really is in the details with EFI.
this IAC valve does that,
to speed it up warm up , put in a 195F thermostat.
this assumes 800 RPM is hot.
most of these engines, do this. new. bewlow.

1: cold start, for 3 to 15sec, 2500 rpm , worse in alaska.
2: then the above DASH pot closes and IAC takes over, at ~1200
3: then as engine heats the IAC closed inch by micro inch a
its now 100% closed and the ECU not controls idle hot.
using the modulated ISC,
there is a fast idle feature on this year, 950 to1000 rpm hot
with these turned on.
1. headlights hot.
2: defrost glass, rear.
3: heater fan on.
4: a/c on if opted.
other wise 800 is normal hot.
0helpful
1answer

First Start Up

Is the check engine light on ? Sounds like the idle air control valve is not working.
0helpful
1answer

Engine runs in idle +/- 2500 rpm

Without checking your car physically, its not possible to give you any idea what it could be or not
0helpful
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Chevy Malibu Cold Idle Problem

Check the water coolant thermostat. If it is stuck in the "open" position you are heating up all the water in the coolant system and this will take time. The thermostat keeps the water in the engine until warmed up to almost normal running temperature, only then does it allow the coolant to enter the radiator.
1helpful
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My 1997 Chrysler Concord idles at 2500 to 3000 rpm when first started and when it warms a little it idles at 2000 rpm and stays there. When I start it right after I turn it off, it starts at 2500 rpm then...

Maybe a short to the TPS or something shorting it out. There's also the IAC that really controls the idle but usually it will cause the RPM's to go up and down a little erratic if bad. The MAF sensor can cause major problems as well but since you already swapped the TPS and it helped and then stopped I would focus on that sensor and especially it's wiring to and from the ECM. Be careful with the sensor signal wire to the ECM can blow it if more than 5v passes or spikes.
1helpful
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My car slams when put into drive. is it the idle

Yes, sounds like the idle speed is too high. If you keep driving like that, you will fry the torque converter / turbine. Since idle is computer controlled, you will have to take it for service tune up. There is one possibility that the rich, high rpm idle used for cold start is not disengaging properly after the engine warms up. Air conditioning will raise the idle speed by a couple hundred rpm, so avoid using it until you have the problem fixed. BTW.....warm engine rpm in idle, and neutral should be around 700-800. Anything over 900-1100 will result in a hard shift into 1st gear and dragging at stop lights.
1helpful
1answer

Engine knock hard over 2500 rpm

Does the oil light come on or the knock occur during the engine warm up after a cold start?
There could be a couple of problems causing the issue. You could have an oil pressure pump or pump pressure regulator sticking. I would have a mechanical oil pressure gauge installed and verify oil pressure at idle and 2500 rpms to make sure oil pressure is in normal ranges.
You could also have excessive piston rod bearing, crankshaft bearing or cam shaft bearing wear that will cause oil pressure to drop too low to prevent the rod knock your hearing at 2500 rpm.
You said a knock and not a ticking noise,so I don't believe a lifter is the issue at 2500 rpm.
Start with the oil pressure check and go from there.
Let me know.
Regards,
13helpful
1answer

Car idles low, stalls after start

Common issue at the shop (i'm a ford technician), here is what I do to correct it.
Here is the most common cause of surges and stalls at stops and low erratic idle speed and rough idle, it is the idle speed control air-bypass valve and throttle valve (IAC for short), they get full of gunk over the miles and cause idle issues (stalls, low idle) like yours, Get a can of intake cleaner from any local parts store, not carb spray, intake cleaner, it is made by a company called CRC, remove the air intake hose to the engine, hold the idle high so the engine won't stall, then spray the can of cleaner into the intake while keeping the engine running, use at least 1/2 the can, shut down the engine and disconnect the battery for 5 minutes, then restart and complete a number of mixed driving cycles, town, freeway, stop and go etc., after a few days the problem will go away as the system will relearn to the clean intake.
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