Question about 1991 Chevrolet C1500

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1991 Chevy C1500 intermittent problem. Failed smog.

169,000 miles, 350 w/air, Auto. Intermittent rough idle/stall combined with what feels like vacuum assist on brakes going out. Failed smog (low 240 ppm and high speed 1830 ppm hydrocarbons). Replaced plugs,wires,rotor, dist cap and oil change. NO CHANGE. Tried to get computer trouble codes but alI I get is a very fast flashing with no pauses. Can not find any cracks or tears in vacuum lines. Sprayed around intake manifold looking for vacuum leak...nothing. Replacing O2 sensor tomorrow. QUESTION: On a fixed income, so should I just replace computer and vacuum assist?

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1991 Blazer 5.7, 142,000 miles, new plugs, air filter, PCV valve, knock sensor. Runs great, right up to when i tried to smog it. It had about 1/4 tank of fuel and about a half of bottle of smog pass, (just wanted to make sure) All was smooth until they started the vehicle to let it warm up! Then after about ten minutes it overheated. I had broke a live wire, which killed the two electric fans charged with cooling the engine. So there i sat for about a hour and half. After a simple repair the engine is now with a temp of about 205 to 210. They conduct the test. 209 hydrocarbons at low idle and 509 at high. They said the 509 is borderline but ok, the low idle hydro carbons is way out (there words). So they suggest I burp the cooling system, see a mechanic and try again. Then I had a aftemarket K

Posted on Aug 10, 2010

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I had a similar problem on my 350 with 265,000 miles; I had changed all of the sensors and the computer with no change. What did fix it was changing the EGR valve. Once that was changed the engine smoothed out and no stalling. Try this before changing out the computer; the EGR valve is around $65 and it is two bolts to change it out.

Posted on Mar 04, 2009

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Dont replace you o2 sensor crimp off the hose going to the brake booster if the idle smooths out the booster is your vacuum leak so replace it.

Posted on Feb 28, 2009

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http://technoanswers.blogspot.com/2012/10/gmc-sonoma-stalls-and-idles-low.html
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It can be issue with IAC( idle air control valve) causing the problem.


There are many other possibilities causing these idle issues. Engine idles rough.

There are few help links with solutions to troubleshoot such idle issues.

I suggest you refer the link below and follow its troubleshooting details:------

Click the link below:-----

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http://technoanswers.blogspot.com/2012/12/ford-expedition-iac-valve-replacing.html

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http://technoanswers.blogspot.com/2012/01/bad-miss-at-idle.html

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http://schematicsdiagram.blogspot.in/2012/03/stumbling-and-stalling-at-idle-after.html

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http://technoanswers.blogspot.in/2012/01/1999-ford-f-150-idles-rough-and-quits.html

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http://repairhelpcenter.blogspot.com/2012/01/engine-stumbles-coming-off-idle-when.html

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http://schematicsdiagram.blogspot.com/2011/12/erratic-idle-on-car.html

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http://repairhelpcenter.blogspot.com/2012/10/cold-start-problem-and-vehicle-shudder.html

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http://repairhelpcenter.blogspot.com/2011/12/low-idle-when-cold-out-side.html

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http://technoanswers.blogspot.com/2012/10/gmc-sonoma-stalls-and-idles-low.html

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http://schematicsdiagram.blogspot.com/2011/12/gmc-idle-air-control-iac-valve.html

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http://repairhelpcenter.blogspot.com/2011/10/1996-camry-intermittent-engine-failure.html

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High Idle Problem

http://repairhelpcenter.blogspot.com/2012/10/high-idle-problem.html

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http://schematicsdiagram.blogspot.in/2012/03/vehicle-stumbling-at-idle-and-shows.html

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Rough idle, staling and Erratic shifting?

http://technoanswers.blogspot.in/2012/03/rough-idlestaling-and-erratic-shifting.html

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While stop engine idles like cylinder missing?

http://schematicsdiagram.blogspot.com/2012/01/while-stop-engine-idles-like-cylinder.html

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These details will help.

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1 Answer

Ford Taurus idle missing


It can be issue with IAC( idle air control valve) causing the problem.


There are many other possibilities causing these idle issues.Engine idles rough.

There are few help links with solutions to troubleshoot such idle issues.

I suggest you refer the link below and follow its troubleshooting details:------

Click the link below:-----
Bad miss at idle? http://technoanswers.blogspot.com/2012/01/bad-miss-at-idle.html

-----------
Stumbling and stalling at idle after engine rebuild?

http://schematicsdiagram.blogspot.in/2012/03/stumbling-and-stalling-at-idle-after.html

------------
1999 Ford F-150 Idles rough and quits when gas pedal is pressed less?

http://technoanswers.blogspot.in/2012/01/1999-ford-f-150-idles-rough-and-quits.html

---------
Engine stumbles coming off idle when warm?

http://repairhelpcenter.blogspot.com/2012/01/engine-stumbles-coming-off-idle-when.html

------------------
Erratic idle on car?

http://schematicsdiagram.blogspot.com/2011/12/erratic-idle-on-car.html

-----------


Cold start problem and vehicle shudder around 2500 to 3500 rpms
http://repairhelpcenter.blogspot.com/2012/10/cold-start-problem-and-vehicle-shudder.html

----------
Low idle when cold out side?

http://repairhelpcenter.blogspot.com/2011/12/low-idle-when-cold-out-side.html

-----------
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http://technoanswers.blogspot.com/2012/10/gmc-sonoma-stalls-and-idles-low.html

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http://schematicsdiagram.blogspot.com/2011/12/gmc-idle-air-control-iac-valve.html

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1996 Camry intermittent engine failure while idle?

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Engine quits at idle?

http://repairhelpcenter.blogspot.com/2011/10/engine-quits-at-idle.html

-----------
Car overheats and Air blows hot at idle?

http://howtobyme.blogspot.com/2011/11/car-overheats-and-air-blows-hot-at-idle.html

---------

High Idle Problem

http://repairhelpcenter.blogspot.com/2012/10/high-idle-problem.html

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While stop engine idles like cylinder missing?

http://schematicsdiagram.blogspot.com/2012/01/while-stop-engine-idles-like-cylinder.html

---------
Idle flair is noticed on car? Rough idle? car will not idle? Erratic idle speed?

http://technoanswers.blogspot.in/2012/02/idle-flair-is-noticed-on-car-rough-idle.html

--------
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http://technoanswers.blogspot.in/2012/02/high-rpm-in-neutral-inconsistant-high.html

-------
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http://schematicsdiagram.blogspot.in/2012/03/vehicle-stumbling-at-idle-and-shows.html

----------
Rough idle, staling and Erratic shifting?

http://technoanswers.blogspot.in/2012/03/rough-idlestaling-and-erratic-shifting.html

-----------
While stop engine idles like cylinder missing?

http://schematicsdiagram.blogspot.com/2012/01/while-stop-engine-idles-like-cylinder.html

---------

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Thanks.

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1 Answer

1991 chevy c1500 stalling


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2 Answers

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1 Answer

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2 Answers

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