The Stupid Engine Questions Thread

Brandon_Lutz said:

I've got a 95 GMC K2500 with the 350 TBI that I'm having some issues with. About two weeks ago we got a patch of bad weather where it pretty much rained for 2 weeks straight non stop. Around that time my truck began to develop a miss around 70 to 75 mph (Anything below that seemed fine). I figured with everything being wet and humid for so long and consistently that I was probably getting moisture into the ignition system. I examined my wires and cap and found carbon tracing on two wires. Upon removing the cap I found a ton of corrosion and tracing inside the cap and the rotor.

Last night I replaced the rotor, cap, and all of the plug wires. Things seemed to be running great. Truck was idling fine and it got back some lost power it had been lacking for a while. I did a few test runs and everything seemed fine. Got up to about 75 with no misses, etc..

Got back to the shop, buttoned everything up and headed home. About 15 mile into my trip, the truck started to miss/surge again around 75 mph/2000 RPM. Slowed down to about 55 to 60 on the interstate and things appeared to run smooth. Anytime I got about 70MPH it would begin to miss/surge again. Finally got into town and came to a red light, truck felt like it was trying to lunge forward while I had my foot on the brake and the idle was rough. Got home a few blocks later and the truck was missing badly under idle.


At this point I'm not sure where to turn to next as I cannot decide if this is a fuel problem or an ignition coil issue (I didn't replace it last night) I'm having some of the same symptoms that I had before but now I have the surging/rough idling issue. I've ordered an adapter to check my fuel pressure at the TBI but that won't be here until Wednesday. Thoughts until then on what could be causing the issue? I inspected the parts I replaced last night and I don't see any new carbon tracing. I also can't see any on the Ignition coil, but it's pretty filthy so it could be hiding some of it.

I also replaced the fuel filter on it last night as well so I know it is not clogged.

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Blue Turd said:

I second checking out the control module. I had similar issues when I installed a high performance coil. After about 15 mins, the module would overheat and the motor would stall out at anything above like 1500 RPM.

Upon inspection the thermal paste that helps keep it cool had dried out completely. It probably would have been fine if I just cleaned both surfaces and reapplied paste, but I opted to just change out with a new one.

I put in an AC Delco Professional ignition control module that is supposedly better built to take the stress of a higher voltage coil. It wasn't much more expensive then the stock part. Either would be fine for you if you plan on running a stock coil.

Just don't buy the no name brands module from the auto parts store, as they are junk. I'd spend the extra cash on the AC Delco.

The part is located under the distributor cap. It was not that expensive either, even for the professional grade one I purchased.

Engine has been running great ever since.

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beardeddummy said:

Best headers for 5.7 vortec

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beardeddummy said:

Full length I have shorty's now

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