acceleration knock

[Chevy1925]

any other suggestions? I dont normally like "throwing parts" at things, but everything seems to point towards injectors. Testing them cost me like 500 bucks last time so I'm trying other ways to figure it out.

you would need to do as suggested before. pull the valve covers and swap the injectors and/or go thorugh and verify all the wiring is correct, ohm the solenoids, and so on. everything does seem to point toward injectors, you have not actually gone in and physically tested things. the only thing pointing to them is others on here based on the video and pics you gave. thats all the info we have to work with so thats all we can give for a probable cause. going deeper will solidify an answer.

your other issue with balance rates is you have a fresh engine thats not completely broke in. its going to skew balance rates IF the bad balance rate cylinder is off on compression in comparison to others.

 

[danzick]

So, going forward, I should do a compression check, and pull the valve covers and ohm the injectors? I dont see swapping the injectors telling me much. If it was just one injector, wouldnt shutting it off while driving kill the knock? it doesnt change the knock. and when my rates decide to act up, its sometimes 3 or 4 cylinders that act up. What should the injectors ohm at?

 

[2004LB7]

So, going forward, I should do a compression check, and pull the valve covers and ohm the injectors? I dont see swapping the injectors telling me much. If it was just one injector, wouldnt shutting it off while driving kill the knock? it doesnt change the knock. and when my rates decide to act up, its sometimes 3 or 4 cylinders that act up. What should the injectors ohm at?

leaking injectors don't always shut off. it can still skew the numbers. moving it do a completely different cylinder and then checking balance rates again and see it follows.

injectors are about 0.5 ohms. you can start by unplugging the harness right at the valve covers and checking ohms there. if you get any over one or so ohms above the meters baseline then you may need to pull the covers and check. but I'd be pulling them anyways as if it's not the solenoids it may be the nozzle or internal so the injectors would have to come out anyways

 

[danzick]

ok. ill investigate further. thanks for the help.

 

[danzick]

I just remembered, When I removed the harnesses, I didnt mark where they went. like left front, left rear, I just threw them in a pile. Does that matter? all 4 looked the same, so I didnt even think about it.

 

[2004LB7]

I think I'd be very hard to mix them up from that. some would be really long while others wouldn't reach

 

[danzick]

im talking about the small harnesses that go under the valve covers.

 

[2004LB7]

im talking about the small harnesses that go under the valve covers.

well, that's definitely possible. red set to the right. orange on the left. polarity doesn't matter

 

[LSxBakakos]

Definitely sounds like an injection issue vs a mechanical one. Compression and leak downs never hurt to run regardless of time on an engine.if it will ease your mind engine wise get a filter cutter(20 bucks on summit) spin the filter,cut and inspect it. Wether it's my daily, my Duramax etc I inspect every filter, every change. Magnetic could be numerous things, which is less worrisome in a sense. non ferrous or "stripper glitter" is when I would worry. If the valve covers do have to come off I'd verify lash again although the video sounds more like a fuel knock/rattle. If it's possible that it acts up under rpm/no load have someone hold the rpm up and either use a stethoscope or a long handled screwdriver as one, and pinpoint where exactly it's coming from

 

[danzick]

It wont do it under rpm without a load. It will only do it driving, while the turbos spool. I have not had a chance to tear into it. I'm going to try and get them out today. I'll start with the passenger side since #3 injector is the one that is by far the worst. I have cut a couple of filters apart. There was a little aluminum in the filter, but I'm pretty sure they were left over pieces from my last blow up that I couldn't get completely cleaned out. LIke my s475, and the drain and possibly feed lines. I called my machine shop and told him what I found in the filter, and he said If the pieces I described to him were new, Id have a real big problem and notice something way off by now.

 

[danzick]

ok I did a compression check. The numbers are really low, but I think I can blame that on my crappy Horrible freight tester with a home made welded fitting to an old glow plug I gutted out. They all seem pretty close. I did number eight last, and that was after the battery charger had a chance to catch up and it spun over noticeably faster than the other 7. My elevation is 4500 ft. Not sure if that has anything to do with it.
1-240
2-240
3-240
4-245
5-240
6-245
7-245
8-255

 

[08lmm72mm]

Well with numbers like those and if you think it's because of your tester I'd get a better quality tester otherwise it's still a guessing game?

 

[danzick]

I was mostly looking for large differences between the cylinders. It doesn't seem have any of the symptoms of low compression. Especially if all 8 were that low. Passenger valve cover off. Nothing looks obviously out of place to me. Anyone see anything?

 

[danzick]

checked the passenger side valve lash. There were a few that the .012 feeler was a bit tight, and one the .012 feeler was a tad loose. I'd guess no more than .001 tight or loose.

I also ohm the injectors. 3 were 0.4, one was 0.5-0.6.

 

[danzick]

Looks like a copper washer may have been leaking a little bit. Would that cause my symptoms? It's the number 5 cylinder.

 

[2004LB7]

Looks like a copper washer may have been leaking a little bit. Would that cause my symptoms? It's the number 5 cylinder.

very well could be. blow by on the copper washer could sound like a knock. you said it would only do it under a load?

also that 4th injector seems to have been running hotter than the others based on the color of the body. unless there is another explanation for the difference in color

 

[danzick]

Not that I can think of. It didn't leak enough to get anything past the oring on the body. Funny, when I go back and look at my pictures, number 5 was the most stable as far as balance rates go. And yes, it only happened under a load BEFORE the boost came on. Wonder why the seal broke? everything was so clean when I assembled it. Everything was new. The seal between the cup and washer was good, but you could clearly see where it leaked past between the washer and the nozzle. Last time I used Vaseline when I installed to keep the washer attached to the injector. Maybe that was the problem? this time I set the washers down in the cup before hand dry.

 

[2004LB7]

reused the hold down bolts? maybe it stretched enough to not get the down pressure needed to crush the washer. what does the washer look like compared to one that sealed good?

 

[danzick]

I dont think any of them stretched. You can usually feel when a bolt stretches while torquing and after just torquing them they all felt the same. You can see how it clamped down heavily on the one side, but just didn't seal on the one side? Possibly a defective washer that was not flat?

when I go around it with a pair if calipers, the shiny spots all measure about 2mm down to about 1.98mm and where it didnt seal, it measures 1.92mm. not sure if thats definitive or not,but an observation.

 

[LSxBakakos]

As the builder said if there was metal like that you'd for sure be having an issue, only downside is debris is never good to have floating around for bearing surfaces or anything else. Considering I just had my valve covers off to do mine there's nothing I see out of the norm in the picture. The .001 difference in lash I wouldnt say was the noise you were chasing. As far as the copper washer I had one that looked identical when I pulled out my stock sticks, mine didn't make noise but every scenario is different, however that cylinder did have discoloring in the injector body and was more difficult to remove than the others. As 2004lb7 stated a compression leak could sound like a knock and would make more sense under load. Unfortunately no matter how sure we all are on doing our part right sometimes qc isn't tight enough and defective parts make their way out the door. Fingers crossed that's your issue, just wonder the price on having them cleaned/checked since you've already got them out