92 chevy truck idling problem

Brandon350 · 09-03-2006, 03:16 PM

Hello all I am new here. I have a question about a 92 1/2 that I am working on for a friend, He bought it with a spun main bearing, I remember when he first got it, it had some idling issues kinda sputtered a little bit, we tore the motor out rebuilt it and put it back in, the motor runs fine going down the road while accelerating but if you stop it idles down and dies, I read the codes and read 13 which is the oxygen sensor and a code 34 for the map sensor, I noticed when we took it apart there is a vacume port on the intake manifold behind the throttle body and someone plugged, I run the map sensor port into the back of the throttle body, do I have a vacumme issue, when you first start it up for about the first 10 to 15 seconds it surges during idling then it picks up and idles about 800 to 1000 rpms. I am lost right now, This truck has been a nightmare from the begining from two different heads on it the wrong exhaust manifolds a cobbled y pipe to make the manifolds work, just one thing after another. Any Ideas what could be my idling issue? Any help is appreciated. Thank you.

chevyguy · 09-03-2006, 11:39 PM

Holy cow, where to start wiht a pieced together truck. I am at a loss.

bradrhale · 09-04-2006, 05:59 AM

get rid of it and start over?? yank everything out and put another rebuilt engine with new exhaust??

chevyguy · 09-04-2006, 08:36 AM

i see alot of troubles in your future. You bought someone elses problem with this one. This is usually what happens when a moron gets under the hood. He hosed it up and sold it to you.

MexToy93 · 09-05-2006, 10:32 PM

Have you replaced the MAP Sensor?

Larry O'Daniel · 09-06-2006, 01:15 PM

Sounds like the idle air speed motor in the back of the throttle body is carboned up and not working. Get some B12 Carb cleaner, spray it down the throttle body to the rear and soak the idle air shaft. If you want, pull the idle air motor off and soak the shaft down good, rinse off all loose debris, and put it back. Gotta get that motor to move freely and work that idle air. If all else fails you can replace it but I would try the cheaper route first. Good luck.

Brandon350 · 09-13-2006, 06:41 PM

I finally fixed the problem, it was a multiple of things, bad egr valve, map sensor, bad oxygen sensor, and had a small vacumme leak under the throttle body. Thanks for all the suggestions.

09-03-2006, 03:16 PM	#1
Brandon350 Junior Member Join Date: Sep 2006 Posts: 2	92 chevy truck idling problem Hello all I am new here. I have a question about a 92 1/2 that I am working on for a friend, He bought it with a spun main bearing, I remember when he first got it, it had some idling issues kinda sputtered a little bit, we tore the motor out rebuilt it and put it back in, the motor runs fine going down the road while accelerating but if you stop it idles down and dies, I read the codes and read 13 which is the oxygen sensor and a code 34 for the map sensor, I noticed when we took it apart there is a vacume port on the intake manifold behind the throttle body and someone plugged, I run the map sensor port into the back of the throttle body, do I have a vacumme issue, when you first start it up for about the first 10 to 15 seconds it surges during idling then it picks up and idles about 800 to 1000 rpms. I am lost right now, This truck has been a nightmare from the begining from two different heads on it the wrong exhaust manifolds a cobbled y pipe to make the manifolds work, just one thing after another. Any Ideas what could be my idling issue? Any help is appreciated. Thank you.

09-03-2006, 11:39 PM	#2
chevyguy Senior Member Join Date: Sep 2005 Location: ALABAMA Posts: 3,160	Holy cow, where to start wiht a pieced together truck. I am at a loss. __________________ When i die, i dont want to walk gracefully thu the pearly gates and turn in a unused body. i want to go sliding thru sideways and turn in a body that has been completely used up.

09-04-2006, 08:36 AM	#4
chevyguy Senior Member Join Date: Sep 2005 Location: ALABAMA Posts: 3,160	i see alot of troubles in your future. You bought someone elses problem with this one. This is usually what happens when a moron gets under the hood. He hosed it up and sold it to you. __________________ When i die, i dont want to walk gracefully thu the pearly gates and turn in a unused body. i want to go sliding thru sideways and turn in a body that has been completely used up.

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09-04-2006, 05:59 AM	#3
bradrhale Moderator Join Date: Apr 2006 Location: Texas Posts: 3,605	get rid of it and start over?? yank everything out and put another rebuilt engine with new exhaust??

09-05-2006, 10:32 PM	#5
MexToy93 Full Member Join Date: Aug 2006 Posts: 19	Have you replaced the MAP Sensor?

09-06-2006, 01:15 PM	#6
Larry O'Daniel Senior Member Join Date: Jul 2006 Location: Tulsa, stationed at Ft. Sill, OK Posts: 90	Sounds like the idle air speed motor in the back of the throttle body is carboned up and not working. Get some B12 Carb cleaner, spray it down the throttle body to the rear and soak the idle air shaft. If you want, pull the idle air motor off and soak the shaft down good, rinse off all loose debris, and put it back. Gotta get that motor to move freely and work that idle air. If all else fails you can replace it but I would try the cheaper route first. Good luck.

09-13-2006, 06:41 PM	#7
Brandon350 Junior Member Join Date: Sep 2006 Posts: 2	I finally fixed the problem, it was a multiple of things, bad egr valve, map sensor, bad oxygen sensor, and had a small vacumme leak under the throttle body. Thanks for all the suggestions.