HefLozano88

I talked to a buddy of mine that used to be a GM mechanic, he said it sounded electrical. I put dielectric grease in every connector in the engine compartment and replaced all the plug wires with MSD 8.5 mm wires and put grease in those as well. The only parts left would be the coils.

How would I know my cat is clogged? Besides replacing it lol

As for the trans, it does it while sitting in the driveway after it has been driven, it wants to die like running out of fuel or misfiring on some cylinders, so I am ruling out the trans. It started out only under a load. It started with a little blip while accelerating from a stop or while moving and trying to accelerate. But it had a knock sensor code, so I replaced the knock sensors and the wire harness to the sensors, intake man gaskets, valve cover gaskets, injector seals, cleaned the throttle body. Once I did all that is when it started doing what it is now which is worse hesitation and missing. No codes. since the new symptoms I have replaced the plugs and wires, and put dielectric grease in all connectors, and cleaned the MAP sensor. I have 60 PSI fuel pressure while running. I don't see the injectors only failing when hot, same goes for the fuel pump. I think it may be a coil or 2, or possibly the cat which would act up once hot.

HefLozano88

I thought that maybe also until I disabled the traction control and it still does it. But thanks for the input.

in2pro

Don't go too crazy with the dielectric grease, as its not conductive and could cause poor electrical connection to the plug and wire... the grease is primarily for the boot so it won't stick and will act as a moisture barrier and is resistant to breakdown under high temperatures...

As for checking out the cats, a scan tool that can read the O2 sensor data can tell you the condition of the cats... see this link for a better understanding..
https://chevroletforum.com/forum/exp...ks-like-60456/





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HefLozano88

I am taking it to my buddies house that has a scope to map out everything from fuel consumption on each cylinder to which cylinders are misfiring. So hopefully I will have some answers tomorrow. Wish me luck.

HefLozano88

So after having it hooked up to a scan tool for over 3 hours, I am no closer to an answer. It told me that all sensors are working properly and the random misfires are on all cylinders. But now tonight some good news I guess. It died just as I pulled it into the driveway, will not restart. No engine light but A code. P0336 crank shaft position sensor. I am going to replace it in the morning and see if it will restart. I hope this is the last part I buy for this issue.

HefLozano88

UPDATE:
well I replaced the crankshaft position sensor. It still hesitates and still wants to die after warming up. And no new codes, so the sensor probably was just a coincidence that is failed. It seems to idle smoother while just sitting but still wants to die.

Joe In NY

I would wipe off the excess di-electric grease. That is NOT helping your spark. You only need a little on the boot material to seal the boots well and make it easier to install and remove the wire sets. Also, make sure the wire are fully on. When I just replaced them on our burb I really had to rotate them around wiggle them a lot till the clicked and sat properly...

I would get a vacuum check and also make sure that the throttle body is clean. I don't know if the Gen III ls-base motors have a separate IAC, I know the Gen IV's dont... But if it does, make sure that is clean and able to move...

HefLozano88

I really didn't use that much grease, and the symptoms before and after are no different. I am leaning towards a bad coil or 2, or a clogged or bad injector. I am going to check to ohms on all the injectors, if that's okay then I will pull them out and clean them out, and then if that doesn't seem to be it then I bought 1 new coil, I plan on swapping it out 1 at a time to see if I find a bad one. If they all seem to be okay then I will have checked everything. and will be at the point of pulling out my hair haha.

Joe In NY

Unplug ALL connections and make sure they are clean, and when re-attcting the plugs make sure they a firmly together. Bad connections can cause all sorts of things... Pull off the Vortec cover and check all the small vacuum lines, vacuum connections, and all the electrical connections...

This one major reason why I love the carbureted 351W in our boats, when they don't run right (very rare), its easy to diagnose and repair!

HefLozano88

I'm loosing my mind!

So after taking a break on it to collect my thoughts, I took my intake off again. before I took it out I removed the throttle body so wouldn't have to disconnect the coolant lines. I stood the intake up on its end where the throttle body would sit and about an 1/8 of a quart of oil dumped out. I have no clue where it came from. Possibly valve stem seal? Possibly rings? not my pcv valve because in 2002 they got rid of that valve and just made an outlet on the drivers side valve cover and inside is a baffle to stop oil from being sucked up. I am going to do a compression test next. Any other suggestions would be great. Thanks


So compression test done. cylinders 1 and 5 have upwards of 170, and the rest are between 150 and 160. Rings are good. Valves are good.