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S-10 Blazer stalls when engine is hot


christian1218
10-10-2009, 04:43 PM
I have a 92' s-10 Blazer with the 4.3 TBI vortec engine 4x4. The problem im having is that she runs fine till she is hot then when you come to a stop or a slow drive she will stall but if you take it out on the highway it runs great again. Just the low RPM's she will stall but only when engine is hot. Ive had the computer read and there are no codes. I've changed bad vacum lines, fuel filter, spark plugs, and spark plug wires. any help is appriciated thanks.

MT-2500
10-11-2009, 09:01 AM
I have a 92' s-10 Blazer with the 4.3 TBI vortec engine 4x4. The problem im having is that she runs fine till she is hot then when you come to a stop or a slow drive she will stall but if you take it out on the highway it runs great again. Just the low RPM's she will stall but only when engine is hot. Ive had the computer read and there are no codes. I've changed bad vacum lines, fuel filter, spark plugs, and spark plug wires. any help is appriciated thanks.

Is it stalling from low engine RPM.

What is engine rpm in park and drive engine hot?

MT-2500
10-11-2009, 09:23 AM
Things to check are dirty or bad IAC valve or pcv valve and or egr valve sticking open.

christian1218
10-11-2009, 01:13 PM
The truck doesnt have an RPM gauge. Its an automatic. But usually any speed under 25 mph and she will stall when the engine is hot. Im about to check the fuel pressure in the next couple of days to rule out that. as far as the EGR valve how do you check if its sticking? Because it seems to have good range of motion when i move the throttle while engine is off.

MT-2500
10-11-2009, 04:34 PM
Vacume or electronic egr valve?
On egr valve pull it when it is dying and see if carbon is sticking it open.
Any check engine lifghts on?
Is the idle good hot in park or when you put in gear foot on brake?

christian1218
10-11-2009, 05:50 PM
its a vacume egr. There are never any check engine lights or codes on computer. It only idles good untill the engine gets hot. When the engine is hot it doesnt matter if its in park or drive or neutral all 3 ways it will be very eratic and want to die. Ill try to pull on egr when its dying. the problem is i have to drive it for 10-15 mins till it runs badly and im usually by myself.

MT-2500
10-12-2009, 08:10 AM
its a vacume egr. There are never any check engine lights or codes on computer. It only idles good untill the engine gets hot. When the engine is hot it doesnt matter if its in park or drive or neutral all 3 ways it will be very eratic and want to die. Ill try to pull on egr when its dying. the problem is i have to drive it for 10-15 mins till it runs badly and im usually by myself.

You need to get a scanner on it and check IAC valve opeation.

But try unpluging iac valve and egr valve when cold engine running and idling good.

Then see if it goes to pot after warm up.
Post back what you find.

TCGrove
10-12-2009, 08:54 AM
How many miles are on it? I've had many if not all the problems that many people post with my 99 Blazer 4x4 with 155,000 miles. For two years now I've had trouble with the thing losing power when going to accelerate, rough idle (especially when stopping), etc. I've changed fuel filters, pump, rotor, wires, plugs, cleaned MAF...but just recently did one that worked miracles.... I changed my O2 Sensors. I tested the one with an ohm meter and propane torch (there's two of them to replace) and found the voltage to be all over the place. I guess these things do wear out. My Blazer runs great now...even better gas milage (if you call 18.4 mpg better than 17 mpg haha). O2 sensors don't read until they hit something like 600 F. The voltage then swings from 0.1 to 0.9 volts and adjusts your fuel to air ratio to hit 1 : 14.7 or something like that. Just some food for thought if your having trouble once the engine heats up.

christian1218
10-12-2009, 09:58 AM
You need to get a scanner on it and check IAC valve opeation.

But try unpluging iac valve and egr valve when cold engine running and idling good.

Then see if it goes to pot after warm up.
Post back what you find.




I will try this but to tell you the truth i dont know where the idle air control valve is located or how to diconnect also with the egr do i remove the vacum lines? and should i plug them whne trying this?

MT-2500
10-12-2009, 10:16 AM
I will try this but to tell you the truth i dont know where the idle air control valve is located or how to diconnect also with the egr do i remove the vacum lines? and should i plug them whne trying this?

Iac valve is on the TBI.
About 4 wire square plug in .

Just unplug the vacuum hose on egr valve,

christian1218
10-12-2009, 01:37 PM
i tried to unplug the iac and egr vacume hoses. at just idling it was fine. but pluged both back in and drove for 10 mins and slowed down and it died. then just unpluged vacume line off egr and still died, pluged vacume lines back in and unpluged iac connector and it doesnt die but idles really high.

MT-2500
10-12-2009, 02:21 PM
i tried to unplug the iac and egr vacume hoses. at just idling it was fine. but pluged both back in and drove for 10 mins and slowed down and it died. then just unpluged vacume line off egr and still died, pluged vacume lines back in and unpluged iac connector and it doesnt die but idles really high.

Sounds like pcm is not controling IAC or iac valve is not working right.

You need to get it on a engine capable scanner and check out IAC valve and iac control.

christian1218
10-12-2009, 05:35 PM
Sounds like pcm is not controling IAC or iac valve is not working right.

You need to get it on a engine capable scanner and check out IAC valve and iac control.




What is the PCM and where would it be located? Where would one find an engine capable scanner?

MT-2500
10-12-2009, 05:38 PM
What is the PCM and where would it be located? Where would one find an engine capable scanner?

The PCM is powertrain control module/computer.
Most good repair shops have the engine capable scanners.

christian1218
10-12-2009, 08:11 PM
so i made an appointment on friday to look at her. They say they are gonna do fuel press test, injector test, starter test, alenoid? test, and computer check. Maybe more. i dont know. but still plan on tryin more till then because they say $75- $175 to look at it.

christian1218
10-13-2009, 04:54 PM
The PCM is powertrain control module/computer.
Most good repair shops have the engine capable scanners.


could all this be from the vacume line on the master cylinder? Because on the master cylinder the connector that conects the vacume line to the master cylinder is a round connector that is wiggly and i dont know if they all feel like that.

christian1218
10-13-2009, 04:58 PM
could all this be from the vacume line on the master cylinder? Because on the master cylinder the connector that conects the vacume line to the master cylinder is a round connector that is wiggly and i dont know if they all feel like that.

MT-2500
10-13-2009, 05:46 PM
You can pull it and plug vacuum line for a test.
But you will have very little brake.
So do not drive it plugged.
Just for a test.

christian1218
10-13-2009, 05:57 PM
well i pulled it off and could hear air leaking out while doing it and i havent drove it since yesterday so i think its probally holding good pressure. And the valve in the connector still has spring action so its probally good right? Also its virtually impossible to recreate the problem while not on a test drive. i tried for like an hour yesterday while parked, and ran it the entire time with out a problem but as soon as your driving for 10-15 mins then the problem is there.

MT-2500
10-13-2009, 06:15 PM
well i pulled it off and could hear air leaking out while doing it and i havent drove it since yesterday so i think its probally holding good pressure. And the valve in the connector still has spring action so its probally good right? Also its virtually impossible to recreate the problem while not on a test drive. i tried for like an hour yesterday while parked, and ran it the entire time with out a problem but as soon as your driving for 10-15 mins then the problem is there.

Valve spring action does not mean much.

If you can not hear vacuum leak at it with brake on or off.
And it does not change idle with it pulled and plugged it should be good.

christian1218
10-13-2009, 07:51 PM
Valve spring action does not mean much.

If you can not hear vacuum leak at it with brake on or off.
And it does not change idle with it pulled and plugged it should be good.


Well i changed the IAC valve and then drove it on the highway for 17 miles then had to slow down for an off ramp and it stalled again. It would not start for about 20 mins. Just turns over but no fire. Usually it will atleast try to fire. I then pulled off the vacume line off the master cylinder and pluged the hole and no change, reatached it and waited about 5 more mins and tried to start again and it fired and drove 1 foot till it died again and so i just left it there and will drive it home tomorrow when its a cold engine again.

MT-2500
10-14-2009, 09:08 AM
When it stalls you need to check for lose of spark or fuel.

christian1218
10-15-2009, 07:09 PM
so i dropped the truck off at the repair shop and they are going to run there tests on it tomorrow. When i find out what they find i will post it. They promiced me they would try to duplicate the problems before they do the tests.

christian1218
10-16-2009, 05:02 PM
so i got the truck back and they said the ignition control module is shot. sho i bought one and gonna go throw it in real quick and hope thats it!!!

christian1218
10-16-2009, 06:58 PM
So i just took it for a test drive with the new part "ignition control module" and it works like a champ. Thankyou very much on all the help. I really appriciate it.

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