89`chevy truck 1500, 4.3 thottlebody


Old 04-12-06, 04:02 PM
reyes45's Avatar
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Join Date: Mar 2003
Location: Michigan, USA
Posts: 71
Cool 89`chevy truck 1500, 4.3 thottlebody

This 89 chevy truck has a high idle problem. It doesn`t matter if the engine is hot or cold, it idles at about1500 or 1600 rpms. I changed the IAC valve and checked timing and problem still persists. By the way, it`s going on 500,00 miles.
All sujestions are welcomed. thank you.
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Old 04-12-06, 04:28 PM
Join Date: Aug 2003
Location: Barre,Vermont
Posts: 472
I'm gonna say the TPS voltage is too high. Probably due to a failed sensor. TPS voltage should fall to around .6 volts with the throttle released. There's three wires at the sensor. One should have five volts, the other .6 at idle and around 4.5 at WOT and the other should have 0 volts(ground).
Old 04-12-06, 06:42 PM
Join Date: Dec 2001
Posts: 2,538
take some carb cleaner and spray around the base of the throttle body to check the tb gasket for leaks they are pretty well known for high idle and a leaking base gasket.
Old 04-12-06, 10:48 PM
Join Date: Apr 2006
Posts: 8
Exclamation if all else fails

there are two knockouts on the bottom of carb/tbi some times things are just too worn and the carb shold be removed and knockouts removed and adjusted you will make it easier to adjust by usin a knockout adjustment tool . PLEASE keep in mind this is accurate for carburated or tbi models hope this helps
Old 04-13-06, 09:29 AM
Join Date: Dec 2001
Posts: 2,538
dont remove any plugs from the tbi.
Old 04-14-06, 03:02 PM
Join Date: Aug 2003
Location: Barre,Vermont
Posts: 472
mmm yeah Bejay, ur right about the throttle body gaskets, I forgot about those.

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