LBZ fuel knock, multiple misfires?

[DIGGLER]

I'm sure you guys have heard this before, but im new to the duramax club, and honestly i feel lost right now.
I bought my truck with an issue, and felt fairly sure it was fuel knock. the guy i bought it from said a gm tech took a look at it and said the issue was a piston wrist pin. sounds similar, i would say.... you can put your head above the engine and cant distinguish which side the noise is coming from. sounds like all over the place, honestly. i dont feel any blowing out of the oil fill, and there is a small amount of smoke out of the exhaust. it needs to turn over and sputter a few times to get started, and also seems to lose its prime after awhile.
i did a few logs with efi live, and the #2 injector had a balance rate of 11.5. the other cylinders were pretty much in tolerance other than #5, which was around 7. rail pressure was showing good, so i replaced #2 injector. truck runs exactly the same. did another log, and #2 is still 11.5 or more. i did the ice pick deal to no avail.
any suggestions? should i do a compression check on all cylinders? crank position sensor? faulty wiring?

 

[sweetdiesel]

I would test compression

 

[DIGGLER]

whats up with all the DTCs? i cleared them just before making the last log, and then rechecked them. all those misfire codes along with the crank position code has me wondering.
i assume the 2 failure to communicate with ecm/tcm module codes happened during cranking when the voltage dropped?

i ordered a diesel compression test gauge, i needed one anyways. hopefully it will be of help.

 

[JD4440]

Ice pick is not for an LBZ. Did you replace # 2 per EFILive or per firing order ? I may be wrong but I think there was an issue there

 

[RKTMech]

You seem to have some sort of wiring or module issue along with other separate issues. All stock truck?
Sorry for my ignorance but "ice pick deal" the problem dosent seem bad enough for self mutilation yet. Do check #2 compression anyway. Maybe gas in fuel?

 

[RKTMech]

Ice pick is not for an LBZ. Did you replace # 2 per EFILive or per firing order ? I may be wrong but I think there was an issue there

Good pull on poss wrong injector.....

 

[JoshH]

Ice pick is not for an LBZ. Did you replace # 2 per EFILive or per firing order ? I may be wrong but I think there was an issue there

The balance rates are correct to the cylinder number.

Like Simon said, compression test will provide more info.

 

[sweetdiesel]

Sorry for my ignorance but "ice pick deal" the problem dosent seem bad enough for self mutilation yet.?

:rofl:


It's for the lly injector to harness fix not role playing Dexter with your girlfriend

 

[RKTMech]

The balance rates are correct to the cylinder number.

Like Simon said, compression test will provide more info.

Ya but did he change the correct injector?

:rofl:


It's for the lly injector to harness fix not role playing Dexter with your girlfriend

Looked but only found a link to DP and dont want to become a member again just to read how people are fixing their harnesses with an ice pick. Es'splain Lucy......

 

[JoshH]

Looked but only found a link to DP and dont want to become a member again just to read how people are fixing their harnesses with an ice pick. Es'splain Lucy......

Poke an ice pick through the injector plug to push the contacts together so it makes a good connection.

 

[DIGGLER]

ice pick deal- basically pressed an ice pick into the injector connector to close the contacts closer together. looking at the connector, it seemed to jive, but as you said i never really saw people doing in on their lbz's. i did it anyway, since it didnt seem to cause any major damage, just 2 small holes in the plug.
the injector i replaced was in the front cylinder on the drivers side.
on my first post, i attached my latest log and dtc's for the truck, are those showing up for you guys?

my truck sounds EXACTLY like the one in these vids.
http://www.youtube.com/watch?v=rFFEocgPX_c

http://www.youtube.com/watch?v=HH24mm4Bguk

 

[Killerbee]

Just stumbled upon this thread looking for something else. Based on your DTC's, I would replace the ECM before proceeding.

 

[DIGGLER]

Just stumbled upon this thread looking for something else. Based on your DTC's, I would replace the ECM before proceeding.

HOLY COW. is there something i can do to rule out the ECM beforehand? are the ECMs on these trucks a high dollar item? (seems like everything else is!)

 

[Killerbee]

Yes. Take it to a dealer, and get the official diagnosis.

The ECM is not that expensive, unless you have the dealer do it. If you were in Phoenix, it would cost nothing to try.

I made that statement, because it looks familiar, I had another E35 that did something similar.

 

[McRat]

There are a few dealers on this site who sell ECM/TCM's, one is Guy at SoCalDiesel.

If you are going to be reflashing your truck, it's always wise to have a spare in your toolbox.

 

[DIGGLER]

i feel like a tard here, but can the dealership hook the ECM up to their computer without the truck? it is not driveable in its current state...

 

[Killerbee]

No, I don't think they have bench equipment. I could be wrong, as I have never asked the question.

 

[ripmf666]

Post the vin and we can see what other trouble this truck has had before at the dealer. Just me but doesn't look like a ECM fix looks like some new injectors and clean the fuel lines and tank. But before that take a comp test on all the cylinders to see what the Heath check is like there first.

 

[DIGGLER]

Vin is: 1GDJC39D46E263487

Story is, the guy was driving the truck along when it began knocking lightly. had it towed to the shop where the knocking got louder, and the tech diagnosed it with a bad wrist pin. instead of repairing the engine, he purchased a new truck and sold this one to me as is. it has 250k on the ticker, and supposedly all the injectors are the ones that came in the truck when new. there was a bit of rusty water in the fuel filter when we cut it open. after sitting for 17 months before i purchased it, the part of the filter where the water sat had begun to rust. (hope that didnt cause a problem!!)
one thing i want to try but have not yet is running the truck off of some fresh known good fuel. they may have gotten some bad fuel... and i have not replaced the fuel in the tank.
i really appreciate the help!

 

[MACKIN]

Can't you shut off each cylinder (Tech II command injector off) to figure out which cylinder is causing issue? With a balance rate in that range in cylinder #2 I would "assume" that is the knock. I had a injector in the 8's and it knocked huge.

Before I dug any deeper I'd certainly find out whats going on there.