1992 Chevy Silverado hesitating acceleration

Tiny
GLENNMCMILLAN
  • MEMBER
  • 1992 CHEVROLET SILVERADO
  • 6 CYL
  • 4WD
  • MANUAL
  • 18,000 MILES
My truck hesitates on acceleration, but gets a little better when it gets to 160*. When first started the idle fluctuates up and down. Items i've replaced, map sensor, idle air control valve, throttle position sensor, egr valve, fuel filter, fuel injectors and connectors, distributor, ignition control modual, timing chain, tempeture sensor, ecm, plugs, wires, cap and rotor.I have no codes to be read. And after 100's of dollars I still have the same problem as when I started.
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Friday, July 3rd, 2009 AT 11:45 AM

3 Replies

Tiny
BUDDYCRAIGG
  • EXPERT
Wow, you've thrown a lot of stuff at this thing.

Surging idles can be a nightmare to solve.

A few more things to check out.

If you have a slight vacuum leak, the ECM keeps trying to control the idle with the IAC, but it doesn't respond like it's supposed to, so the ECM keeps adjusting it back and forth.

I know this will sound crazy, but sometimes cleaning where the ground wires attach to the engine helps.

Might check the fuel pressure to see if it is staying steady.

And on rare occasion, even though you should never have to do it, I have adjusted the throttle plate stop screw a little one way or the other and that seemed to help it.

Sometimes there is just no silver bullet for idle problems.

If you unplug the IAC, does the idle stay steady?
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Friday, July 3rd, 2009 AT 9:25 PM
Tiny
GLENNMCMILLAN
  • MEMBER
I did a vacuum check and it showed good I have the idol thing better but the truck still hesitates when I give it gas. Thanks for the help and if I ever fix it, i'll let you all know how I did it
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Monday, July 6th, 2009 AT 3:06 PM
Tiny
BUDDYCRAIGG
  • EXPERT
Can you do a fuel pressure test and blip the throttle a few times. The pressure should go up just for a second or two when you open the throttle and the vacuum goes down.
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Monday, July 6th, 2009 AT 4:42 PM

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