Misfire between 45-55 mph

[Mangonesailor]

Brand new cap rotor and whole distributor

Have your ignition control module tested at an auto parts store. I've had one go bad in a 4.3 before. I'd have to pull over and let the engine cool off before I could get down the road again. Basically wouldn't let the ignition timing advance.

 

[letitsnow]

1997 k1500 5.7l, misfires between 45-55 mph. No codes it’s done this even after a tune up and changing a bunch of parts

Are you sure that the tq converter locking up isn't what you are hearing?

 

[_nickjoseph]

Are you sure that the tq converter locking up isn't what you are hearing?

It locks up yes but it just doesn’t feel right. It feels sluggish and like there’s no power. My uncle told me it’s probably because my exhaust is cut right after the cats, the kid before me did that to it

 

[Squirrelizer]

Fuel Pressure Regulator? Mine ran pretty choppy with a bad fuel pressure regulator.

 

[Chevy-SS]

I had same truck, same engine, and same problems. My issue turned out to be fuel pump. I tried a couple of off-brand pumps and they only lasted a month or two each, it was ridiculous. I then bought OEM fuel pump and truck ran like new.

Maybe the first thing I would try is replacing the fuel filter and run a bunch of injector cleaner in the fuel.

Spark plug wires may look OK, but they could be cross-firing. I would recommend separating them from each other as much as possible to see if that helps.

 

[_nickjoseph]

Fuel Pressure Regulator? Mine ran pretty choppy with a bad fuel pressure regulator.

Had that changed supposedly when I upgraded my fuel injectors

 

[_nickjoseph]

I had same truck, same engine, and same problems. My issue turned out to be fuel pump. I tried a couple of off-brand pumps and they only lasted a month or two each, it was ridiculous. I then bought OEM fuel pump and truck ran like new.

Maybe the first thing I would try is replacing the fuel filter and run a bunch of injector cleaner in the fuel.

Spark plug wires may look OK, but they could be cross-firing. I would recommend separating them from each other as much as possible to see if that helps.

I have the wire looks seperating them and have changed the filter and ran so much cleaner through. I can try the pump I guess it won’t hurt since my needle bounces all over the place anyways

 

[Mangonesailor]

You mentioned in your original post you "changed a bunch of parts" and did a tune up.

So, what parts are new? Do you still have the old stuff? Have you gotten the ignition module tested?

 

[_nickjoseph]

You mentioned in your original post you "changed a bunch of parts" and did a tune up.

So, what parts are new? Do you still have the old stuff? Have you gotten the ignition module tested?

I’ve changed the distributor ,cap and rotor and sensor. I’ve changed all plugs and wires and upgraded my fuel injectors and changed the egr valve. Also changed the tps. No how do I get the ignition module tested?

 

[Schurkey]

Connect a scan tool, look at the data stream. The answer is almost certainly in there.

Verify fuel pressure. Wouldn't hurt to verify cranking compression.