Mechanics

CHEVY WITH 4.3L

1996 Chevrolet S-10 • 6 cylinder 2WD Automatic • 125,000 miles

I have a 1996 Chevy S-10 with a 4.3L. The truck suddenly started running rough and backfiring with a P0300 troublecode. I have replaced the sparkplugs, plug wires, rotor, distributor cap, fuel filter, and camshaft position sensor. I also checked the fuel pressure at 55 psi. The coil checks out with ohm meter. No noticable vacuum leaks. It is still running the same. Suggestions?
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Swilsonsr
August 10, 2011.




Backfiring out exhaust or intake? You may have an injector problem.

Tiny
Fixitmr
Aug 10, 2011.
Exhaust

Tiny
Swilsonsr
Aug 10, 2011.
You bought some parts but it still could be a distributor related problem. Teh gear drive or the module or the hall pickup. Or your MAF could be dirty or your coil could also be acting up or it could be your injection system. And there's always the EGR to consider and I think your vehicle has 4 OX sensors? This engine system has been a veritable headache for too many owners! But most suffer injection woes. And it's almost always dirty/sticky popits or the fuel pressure regulator.

Tiny
Fixitmr
Aug 11, 2011.
I checked the coil with an ohm meter and it was in specs, but could it still act up. The truck runs the same whether cold or warmed up. Would there not be a troublecode for the others (MAF, OX sensors, EGR, and injectors)? With respect to the distributor, what and where is the module? Is the Hall pickup also known as the crankshaft position sensor? Is there any way I can bench test these items (Module, Hall pickup, EGR, OX sensors, and injectors) myself? Where would you start looking for the cause of the problem? Should I just replace certain items?

Tiny
Swilsonsr
Aug 11, 2011.
What about the crank sensor? Hall is cam position. Have you pulled intake to look at spider injection? Here's a test page/site for your stuff.

Tiny
Fixitmr
Aug 12, 2011.
Another thing. Take a compression test! These engines have been known to blow the head gasket between cylinders causing rough running and misfire code.

Tiny
Fixitmr
Aug 12, 2011.
Ok, I'm going to give it a try. Will let you know. Thank you
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Tiny
Swilsonsr
Aug 12, 2011.
I replaced the spider injection and fuel pressure regulator, The truck still runs the same with a P0300 code. Compression is normal in all cylinders. What else can it be?

Tiny
Swilsonsr
Aug 15, 2011.
Also the code reader has "inc" for catalyst mon, Evap Syst Mo, Oxygen Sensor Mon, Oxygen Sen Htr, and EGR system mon. Even after allowing the engine to run several minutes.

Tiny
Swilsonsr
Aug 15, 2011.
Inc means incomplete. You didn't complete a proper diving cycle to complete tests.

Tiny
Fixitmr
Aug 15, 2011.

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