Mechanics

SEVERE ENGINE BUCKING/MISSING UNDER LOAD (IN OVERDRIVE)

All Other Makes All Other Models

Hello. My Silverado has a 350 vortec engine. When at or near highway speed, it will start severely missing, bucking, and hiccupping, most of the time under load (up hills) and even on flat roads sometimes. This always happens in overdrive. If I accelerate to drop to a lower gear, the missing problem goes away until it goes back into overdrive. This condition has been happening for over a month, and getting worse by the day. The truck has a recent fuel pump, and (1) O2 sensor (suggested by an engine scan as not working properly, so it was replaced), and today I replaced the cap and rotor. I don't know what else to try. Please help!
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Theskymarty
April 14, 2013.




What year is it? Then scan for codes and check fuelpressure also check for a vacuum leak.

Tiny
Hmac300
Apr 14, 2013.


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