Not Your Common Rough Idle (04.5 LLY)

[hopkins_fam]

Yes its correct, i believe its not pulling because my pre-pump filter is a CAT unit and it also has a primer, not sure.

But i ordered a non primer base to swap it out and Im gonna do away with the pump fir now. Trucks starting to get a pretty loud fuel knock under load now

I took the outlet off the pump to see how it flowed, but it has a good stream (not a lot of pressure) its like pump, pump, pump. Not really a steady stream like a hand pump or something. The stream never stopped but looked like it may slow down a split second, pump, slow down, etc...

 

[PureHybrid]

Well take it apart and see! From what I remember they're a pretty simple pump.

 

[hopkins_fam]

Well take it apart and see! From what I remember they're a pretty simple pump.

Anyone know how they come apart exactly? Looks like its the top fitting half and bottom pump half are crimped together.

 

[PureHybrid]

If its the style I think it is, just remove the three mounting studs on top. The top plate will come off and the vanes pull out the top IIRC.

 

[hopkins_fam]

Still haven't really got anywhere. Hopefully i have a appointment with a local dealer to have the truck reflashed to give me a fresh starting point.

Also at warm idle my actual FPR is going from 4.1-4.5, I've tried e-mailing alligator about the warranty but still haven't heard anything back.

 

[04duramaxlly]

bump.. i am having this same exact problem.. did you ever figure out what was causing it?

 

[hopkins_fam]

It was between a bad injector or wiring. I swapped 2 injectors and the engine harness and never had another problem

 

[Burn Down]

I was about to recommend running a fuel return rate test on the injectors. My truck is doing the same as yours did, it will stumble and knock out of the blue, then run fine for a week then back at it again, it's become pretty constant now. I have swapped all the electronics. The only thing left is the harness or injectors... When I get un annoyed with it I planned on doing the return rate test on the injectors, I'm positive one or two of them is the problem. I think mechanically they are popping open whenever they feel like it. I have shut each one off with a tech2 and the rough idle and knock is still there. If nothing shows up on the return rate test then I will pull them and send them out to be tested, balanced and have the tips put on.

 

[hopkins_fam]

Mine was constant after 160-170 degrees.

I do have another LLY harness but the GPC plug is broke, but I also have the original harness that came off my truck (nothing was ever wrong with it) only thing missing on it is some loom and one injector connector.

Im getting ready to put the harness that came with my used engine on as soon as weather clears.

I think I may still have some wiring demons on the ECM/TCM harness side where my hydroboost has leaked forever all over the harness.