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Old 06-06-2004, 02:01 PM
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4.3 Vortec Woes..

I just bought a 93 4.3 Liter Vortec equiped Blazer for my commuter vehicle, and it has some issues. I;m engine savvy, but am not real familiar with these 4.3's, and just wanted to see if anyone has heard of this problem, or has any ideas on a likely cause. THe symptoms are as follows:

Hesitiation - usually as the RPM's rise in first and second gear, it hesitiates and feels like its holding itself back for a few seconds or longer...as it shifts into the next gear, things are smooth again.

I don't notice it as much at freeway speeds, mostly 1st-2nd gear acceleration (makes pulling into fast moving traffic not so fun)..

It does not do it everytime, sometimes is feels perfect, strong and smooth.. i would say that 80% of the time is does its hesitiation.

Black exhaust - the exhaust, especially during startup and warmup is very sooty and charcoal-like. There is not really any black smoke, but a nice black spot of soot on the ground quite quickly.

I don't think there is a blown head-gasket (compression good, oil looks fine). Maybe something EGR or fuel related?? Any help or ideas is appreciated.

Thanks

Paul

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Old 06-06-2004, 02:16 PM
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You should have a check engine light glowing.

Sticky EGR valve is the first thing that pops up in my noggin. If the EGR valve moves freely do an impedance check on the EGR position sensor. Make sure that the idle air control valve is functioning properly too.

If none of these things appear to be the cause then you may want to take it to a qualified tech or the dealership and have them test the ecu for stored trouble codes. If it has none then you likely have a problem with the ecu itself

Larry
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