My engine will not idle?

Tiny
COALWOLLF
  • MEMBER
  • 2002 CHEVROLET BLAZER
  • 4.3L
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 166,000 MILES
Okay, so here is my problem. It was running last week but rough backfiring in the cylinders and acting like it was not getting enough fuel. So naturally I looked at the fuel system pump seems to be turning on and working, no leaks, and seems to be getting to the injectors. Replaced the filter and it ran a little better but not much. Stopped and had the codes read and it had a few but I need to get a new reader to tell you them all I know that four of them where the knock sensor, mass air flow, and two o2 sensors. So I replaced the maf sensor, air filter, and tried to start it but now it only runs for a few seconds then fades out and stalls it will start up again but will not idle no matter what I do and I have looked at what I can think to look at so any ideas? I also know it is not the injectors since it also had no signs of that either.
Tuesday, October 30th, 2018 AT 12:16 PM

50 Replies

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Good afternoon.

This sounds like you have a vacuum leak, dirty throttle bore or the IAC motor is not working but to be sure lets check out these guides to help us fix it.

https://www.2carpros.com/articles/stall-at-idle

and

https://www.2carpros.com/articles/throttle-actuator-service

and

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

if okay the first thing I would do is check the actual fuel pressure. Low fuel pressure will cause all these codes.

You can rent a tester at a parts store. There is a test port on the supply line back by the distributor. The tester just goes on that fitting for the test.

Roy

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator
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Tuesday, October 30th, 2018 AT 1:03 PM
Tiny
COALWOLLF
  • MEMBER
  • 2 POSTS
The knock sensor and the mass air were both the problem. The mass air flow was bad and the knock sensor was unplugged and bad I bought a new one of both and installed them and it is running fine.
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Wednesday, November 7th, 2018 AT 3:59 PM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Okay, good find.

Glad you got it fixed.

Roy
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Wednesday, November 7th, 2018 AT 4:08 PM
Tiny
GERALD JACOBS2
  • MEMBER
  • 2 POSTS
  • 2002 CHEVROLET BLAZER
  • 116,345 MILES
I'll start the car and and take my foot off the gas it'll cut off. It won't keep up with rpm.
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Saturday, January 30th, 2021 AT 8:48 AM (Merged)
Tiny
JONNYB1963
  • MECHANIC
  • 252 POSTS
HI Gerald,

Based on what I read here it could be a couple of things.

First it could be the Idle Air Control valve is not working properly. (See link below)
https://www.2carpros.com/articles/idle-air-control-valve-service

Or it could be a large vacuum leak (See link below)
https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Just note that if it is a vacuum leak it would have to be significantly large, something the size of the PCV valve line.

Regards
Jon
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Saturday, January 30th, 2021 AT 8:48 AM (Merged)
Tiny
HANSENCOLT45
  • MEMBER
  • 6 POSTS
  • 2002 CHEVROLET BLAZER
  • 4.3L
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 174,000 MILES
My vehicle started shortly after hurricane Michael, acting up. It would sputter every now and then when I sustained a specific speed and rpm for too long, and would sputter or stall when idled or stopped, and only idling at 50 rpm. Whenever it has shut off I have been able to jump into neutral and start it did not back up. Tried cleaning my throttle body, used some sea foam to clean the fuel system. It has aggressively gotten worse however. I took it to my mechanic and he said it seemed to be misfiring and suggested a new distributor cap (I do not think it has one) new plugs and injectors. I have been trying to make it last as long as I can without the parts because my money is tight since hurricane Michael came through Panama City. Last night it shut off when I was slowing down but now it does not start back up. I am about to go try to change my spark plugs in hopes I can at least get it home. Any and all help is welcome. Please
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Saturday, January 30th, 2021 AT 8:48 AM (Merged)
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 44,215 POSTS
Hello,

I would start with a tune up but let's check the battery and the connections which can cause the issue you are describing. Here are two guides that should help us get started:

https://www.2carpros.com/articles/how-to-tune-up-a-car-engine

(use OEM parts)

and

https://www.2carpros.com/articles/everything-goes-dead-when-engine-is-cranked

with

https://www.2carpros.com/articles/car-battery-load-test

Please run down these guides and report back.

Cheers, Ken
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Saturday, January 30th, 2021 AT 8:48 AM (Merged)
Tiny
GERALD JACOBS2
  • MEMBER
  • 2 POSTS
  • 2002 CHEVROLET BLAZER
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 162,157 MILES
When I start it it will start, but soon as I take my foot off the gas it shuts down.
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Saturday, January 30th, 2021 AT 8:48 AM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,779 POSTS
This can be the result of a few things. An engine vacuum leak, dirty throttle body, or even the idle air control valve.

What I suggest is to first confirm there are no engine vacuum leaks. Here is a link showing how that is done:

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

Next, consider cleaning the throttle body / throttle plate. Here is a link showing how that is done:

https://www.2carpros.com/articles/throttle-actuator-service

If that still doesn't help, then I suspect it is related to the idle air control calve (IAC). The IAC is responsible for maintaining idle speed. Take a look through this link. It shows in general how one is serviced and the second shows general replacement.

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

https://www.2carpros.com/articles/how-to-replace-an-idle-speed-control-motor-iac

__________________

Here are directions specific to your vehicle for replacement. The attached pics correlate with the directions.

________________

2002 Chevy Truck S10/T10 Blazer 4WD V6-4.3L VIN W
Procedures
Vehicle Powertrain Management Fuel Delivery and Air Induction Idle Speed/Throttle Actuator - Electronic Service and Repair Procedures
PROCEDURES
IDLE AIR CONTROL (IAC) VALVE REPLACEMENT

REMOVAL PROCEDURE

pic 1

1. Turn OFF the ignition.
2. Remove the air cleaner outlet resonator.
3. Disconnect the idle air control (IAC) valve harness connector.

pic 2

4. Remove the IAC valve mounting screws.

pic 3

5. Remove the IAC valve and O-ring from the throttle body assembly.

CLEANING AND INSPECTION PROCEDURE
1. Clean the IAC valve O-ring sealing surface, pintle valve seat, and air passage.
Remove excess carbon deposits with a small amount of carburetor cleaner on a parts cleaning brush. Follow any instructions on the cleaner container regarding cleaner usage.
DO NOT use a cleaner containing an extremely powerful solvent such as methl ethyl ketone.
Shiny spots on the pintle and seat do not represent a bent or misaligned pintle shaft.
If heavy deposits are present in the air passage, remove the throttle body for a complete cleaning.

IMPORTANT: DO NOT reuse the original O-ring.

2. Replace the IAC valve O-ring.

INSTALLATION PROCEDURE

IMPORTANT: Use an identical pan when installing a new idle air control (IAC) valve. The IAC valve pintle shape and dimensions are designed for specific applications.

pic 4

1. On a new IAC valve, measure the distance between the IAC valve pintle and mounting flange. Use finger pressure to slowly retract the pintle if the distance is more than 28 mm (1 - 1/8 in).

pic 5

2. Lubricate the IAC valve O-ring with clean engine oil.
3. Align the flange holes with the mounting holes on the throttle body assembly.
4. Insert the IAC valve through the O-ring into the throttle body assembly.

NOTE: Refer to Fastener Notice in Service Precautions.

IMPORTANT: The screws used to attach the IAC valve are coated with thread locking adhesive. Clean the attaching screw threads and apply thread locking material GM P/N 1052624 or equivalent.

pic 6

5. Install the IAC valve mounting screws.

Tighten
Tighten the screws to 3 N.m (27 lb in).

pic 7
6. Connect the IAC valve harness connector.

pic 8

7. Install the air cleaner outlet resonator.
8. Perform the IAC Reset procedure:
8.1. Turn ON the ignition, with the engine OFF, for 5 seconds.
8.2. Turn OFF the ignition for 10 seconds.
8.3. Start the engine and check for proper idle speed.

Let me know if this helps or if you have other questions.

Take care,
Joe

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Saturday, January 30th, 2021 AT 8:48 AM (Merged)
Tiny
COOLWOOD42
  • MEMBER
  • 2 POSTS
  • 2001 CHEVROLET BLAZER
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 77,000 MILES
My car ran just fine until yesterday when I stopped at a store, shut it off. When I came out and started the car it would not idle in drive. If I put it in neutral it would idle but very poorly. I drove home between drive and neutral at stop signs to keep it running. This morning the car seems to be fine, It had been sitting out for about 4 days in the cold. But I have driven about 25 mile with no problems before it acyed up
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Saturday, January 30th, 2021 AT 8:48 AM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,779 POSTS
Has the check engine light come on? Also, when was the last tune up?
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Saturday, January 30th, 2021 AT 8:48 AM (Merged)
Tiny
COOLWOOD42
  • MEMBER
  • 2 POSTS
Yes, actually its been on for some time. The dealer says nothing is wrong and just resets it. I guess just some kind of error code. The car does have an extended warranty, maybe they just dont want to fix it
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Saturday, January 30th, 2021 AT 8:48 AM (Merged)
Tiny
BETSYBLZR2000
  • MEMBER
  • 2 POSTS
  • 2000 CHEVROLET BLAZER
2000 Blazer 4WD 78,500 miles Automatic
Just recently I have had issues with my blazer quitting after stopping at a stoplight. Generally when I first drive the vehicle it runs fine but after driving for a while and I stop at a light - then I press on the gas - it will just quit - it will start right back up and I can be on my way. Then randomly at another light it will quit.
I just had a 75, 000 mile service where they replaced the fuel filter and spark plugs and whatever else goes along with it. However it will still quit running randomly after its been running for awhile. And not sure if it matters but its las vegas so its been 110 degrees out lately. Also when the air is running sometimes when you step on the gas - it doesnt always move right away. What do you suggest?
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Saturday, January 30th, 2021 AT 8:49 AM (Merged)
Tiny
2CARPRO JACK
  • MECHANIC
  • 11,533 POSTS
When you say it doesnt move right away, does the engine rev up like the trans is slipping? When it dies, does it sputter out like it has run out of gas or does it just shut down?
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Saturday, January 30th, 2021 AT 8:49 AM (Merged)
Tiny
BETSYBLZR2000
  • MEMBER
  • 2 POSTS
I guess when I say it doesnt move - I am pressing on the gas many times to the floor but the blazer doesnt accelerate, it is moving at a maybe 5 miles per hr but wont go any faster - then finally it does move and accelerate.
When it stalls it always been after stopping at a stop light - I go to press on the gas to go and sometimes it will move forward but be jerky then stall, but then there have been times when I have stepped on the gas and it has just quit. It always starts right back up and I can be on my way.
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Saturday, January 30th, 2021 AT 8:49 AM (Merged)
Tiny
2CARPRO JACK
  • MECHANIC
  • 11,533 POSTS
Start by having the PCM scanned for trouble codes
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Saturday, January 30th, 2021 AT 8:49 AM (Merged)
Tiny
MATTCHEVYGUY333
  • MEMBER
  • 4 POSTS
  • 1999 CHEVROLET BLAZER
  • 157,000 MILES
I found a sensor or solenoid on the transmission that when I unplug it it doesnt do it but the truck doesnt have an acceleration if someone can tell me what this sensor is it plugs into the tranny has like 10 prongs and 2 sets of wires hooked into it

Please help

Thanks matt
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Saturday, January 30th, 2021 AT 8:49 AM (Merged)
Tiny
MHPAUTOS
  • MECHANIC
  • 31,937 POSTS
I feel that you have unplugged the main transmission harness, from what you describe I feel that the TTC lock up solenoid has failed, I suggest that you get a diagnostic scan done to confirm this, start here.
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Saturday, January 30th, 2021 AT 8:49 AM (Merged)
Tiny
LILENGLAND1Q
  • MEMBER
  • 1 POST
  • 1996 CHEVROLET BLAZER
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 190,000 MILES
When I step on the brakes, I get resistance as it only goes down a bit and the car doesnt slow down. I have to step on it hard to stop the car and I hear what sounds like a hissing hydraulic sound. My car sometimes stalls when I try to move after a stop. I usually put it in park at a stop sign to prevent this stalling.
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Saturday, January 30th, 2021 AT 8:49 AM (Merged)
Tiny
SWILLIAMS
  • MECHANIC
  • 597 POSTS
That sounds like a bad vacuum booster unit. When the pedal goes down is it much harder than it used to be? If so check the large line to the booster and the check valve as well. If they are OK Disconnect the hose and plug it. Now test drive it. If the stalling has gone away and you don't hear the hissing the booster is bad. Not hard to change out if you're mechanically inclined.
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Saturday, January 30th, 2021 AT 8:49 AM (Merged)

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