Hey guys,

I am working on my buddies truck it's a 1996 Chevy K1500 with a 305 and a 5 Speed Manual Tranny.We recently put in another 305 with Less millage on in, before we install the motor we changed the the timing chain, timing chain gears, cap and rotor, water pump, oil pan gasket, new belt,new rad, new intake and gaskets, Distributor shaft and new ACDelco plugs and wires Plugs are gaped correctly. We installed motor and timed with timing light. Although when you are going down the road in 5th gear at a low RPM the engine back fires misfires and runs like a bag of ****. I am thinking maybe the ignition control module is bad? If any one could shine some light on this problem that would be great.

Thanks
RitualJman

 

Is it setting any codes? Have you checked the fuel pressure/fuel filter? Also drain some fuel into a clean bottle, let it sit. Make sure you don't have bad gas or possibly water in the fuel.

 

We have checked fuel pressure and also we started with a little bit of water in the fuel, although we drained the tank let it dry then roughly half filled the tank. Although we took the truck to our local GM dealer they charged me almost 500 bucks and couldn't tell me what the problem was, yet the had the truck all day. ALso the only codes i am getting are for the O2 Sensor although i replaced them with new ones just before motor was swapped.

 

Are you still getting O2 codes, and if so, what are they? What rpm in 5th gear is this happening? It might be the ignition timming doesn't like that low of rpm in that high of gear.