Noob to the duramax diesel - Competition Diesel.Com

GreasemonkeyHd · 08-27-2021, 07:21 PM

Just bought my first duramax truck. Only had cummins trucks and one 7.3 that I still have as my primary vehicle. It smokes and misses steadily on one cylinder. The balance rates looked like Cylinder #4 was the problem reading a 9.04, I had no CEL . It doesent tick or have any blowby whatsoever. Lb7 cab lly motor, previous owner said one of the diesel mechanics he took it to said its the ficm the other two said injectors. Fires right up every time. I put some hot shots in it and ran it in the driveway because I heard good things about it , smoke cleared almost all the way up and was running way smoother. Took it for a drive about a mile or so down the road nice and easy. Started clattering when I went to turn around. Check engine light came on and it started idling rough and clattering like a tractor. Limped it back home and it was throwing a p0201 code. Shut the truck down and let it sit for a few minutes then fired it back up. Ran smooth again with no smoke, gave it a couple Rev and immediately went back to clattering and running rough. My scanner says miss communication with ecm every time I try to clear a code even though the check engine light shuts off. Says check my plug in and ensure the vehicle is on. Seems to throw a a different injector control circuit code every time the cel comes on. Checked the harness by the alternator already and ice picked cylinders 1, 7, and 2 injector plugs

jasonc · 08-27-2021, 07:31 PM

Needs another can of Hotshot

GreasemonkeyHd · 08-27-2021, 07:56 PM

Quote:

Originally Posted by jasonc

Needs another can of Hotshot

Ya think so? The balance rates read these numbers after the drive down the road the first time and I don't think the truck was all the way warmed up. Haven't checked them again since I ice picked 2 and 7
Cylinder #1 -3.40
Cylinder#2 -1.02
Cylinder#3 -2.76
Cylinder#4 9.04
Cylinder#5 2.40
Cylinder#6 0.88
Cylinder#7 -1.20
Cylinder #8 -3.71

jasonc · 08-27-2021, 08:01 PM

I just had a hard time reading that run on post.

Break things up easier to read.

GreasemonkeyHd · 08-27-2021, 08:55 PM

Quote:

Originally Posted by jasonc

I just had a hard time reading that run on post.

Break things up easier to read.

sorry I copied and pasted from a fb page I joined where I didn't get a whole lot of response. Haven't posted on a forum in a while so I don't recall how to post videos or pictures either. Long story short I've ice picked the injector plugs with no effect on how it runs. Just fired it up a minute ago and it was smoking like a chimney with a dead miss. Injector 4 balance rate was 15. Something.

ikeG · 08-29-2021, 06:59 PM

Swap injector 4 into another hole and read your balance rates.

Sent from my SM-G960U1 using Tapatalk

DirtyMaxx03 · 08-30-2021, 08:06 AM

ice pick trick didnt help at all?

GreasemonkeyHd · 08-30-2021, 08:42 AM

Quote:

Originally Posted by ikeG

Swap injector 4 into another hole and read your balance rates.

Sent from my SM-G960U1 using Tapatalk

I might just try that.

GreasemonkeyHd · 08-30-2021, 08:43 AM

Quote:

Originally Posted by DirtyMaxx03

ice pick trick didnt help at all?

I think it did some because I'm not getting different codes other than 1 and 8 now

DirtyMaxx03 · 08-30-2021, 12:10 PM

Quote:

Originally Posted by GreasemonkeyHd

I think it did some because I'm not getting different codes other than 1 and 8 now

sometimes the icepick trick doesnt do the job and you have to install new plugs on the injector harness. cut the old ones off and splice new ones on. everything you're mentioning sounds like a harness issue

GreasemonkeyHd · 08-30-2021, 01:19 PM

Quote:

Originally Posted by DirtyMaxx03

sometimes the icepick trick doesnt do the job and you have to install new plugs on the injector harness. cut the old ones off and splice new ones on. everything you're mentioning sounds like a harness issue

Got a part number? Gm dealer only?

JWhite · 08-30-2021, 01:52 PM

Merchant Auto sells a kit with a bracket. I don't think it's for every plug though, just 2&7

Edit: I looked at their site and they carry individual pigtails. Probably not going to like the price

GreasemonkeyHd · 08-31-2021, 06:24 AM

Quote:

Originally Posted by JWhite

Merchant Auto sells a kit with a bracket. I don't think it's for every plug though, just 2&7

Edit: I looked at their site and they carry individual pigtails. Probably not going to like the price

I don't like the price or quality of much of anything anymore. My local parts store said 66 bux a piece for non ac delco ones. Probably junk

GreasemonkeyHd · 08-31-2021, 09:25 PM

Quote:

Originally Posted by DirtyMaxx03

sometimes the icepick trick doesnt do the job and you have to install new plugs on the injector harness. cut the old ones off and splice new ones on. everything you're mentioning sounds like a harness issue

Well I took an extra good look at the truck today. Looks like #8 injector has been replaced along with the plug, plus there is a weird almost home made bracket or something under it. It's thrown a code for 8 a time or two. Also #4 has weird black sludge around the line nut that indicates leakage although I don't see any fuel leak while it's running. The truck will have a dead miss and smoke like a chimney while it's cold, once it gets kinda warm it will smooth out and the smoke will clear then all of the sudden either 1, 6 , or 8 injector control circuit code and run like a tractor. The pigtail for #1 appears to also have been replaced.

ikeG · 09-01-2021, 04:28 AM

That bracket is part of GMs repair kit. That is cyl 7 by the way.

Sent from my SM-G960U1 using Tapatalk

GreasemonkeyHd · 09-01-2021, 06:30 AM

Quote:

Originally Posted by ikeG

That bracket is part of GMs repair kit. That is cyl 7 by the way.

Sent from my SM-G960U1 using Tapatalk

Wait a minute....I thought from what everyone said, passenger side was 2468 and d side was 1357?

ikeG · 09-01-2021, 06:50 AM

Quote:

Originally Posted by GreasemonkeyHd

Wait a minute....I thought from what everyone said, passenger side was 2468 and d side was 1357?

Drivers is 2468

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weazel · 09-01-2021, 08:07 AM

It’s flip flopped on the duramaxes, 1 is pass side, 2 is drivers side..

GreasemonkeyHd · 09-01-2021, 08:19 AM

Quote:

Originally Posted by weazel

It’s flip flopped on the duramaxes, 1 is pass side, 2 is drivers side..

Lol well I've been thinking bass ackwards the whole time

weazel · 09-01-2021, 09:16 AM

Quote:

Originally Posted by GreasemonkeyHd

Lol well I've been thinking bass ackwards the whole time

yeah it took me a minute to figure that out too lol

08-30-2021, 01:52 PM	#12
JWhite Name: JWhite Title: Trained monkey Status: Not Here Join Date: Aug 2009 Location: F Burg Ohio Member`s Gallery Posts: 1,817	Merchant Auto sells a kit with a bracket. I don't think it's for every plug though, just 2&7 Edit: I looked at their site and they carry individual pigtails. Probably not going to like the price __________________ GMC with a LiLLY Last edited by JWhite; 08-30-2021 at 01:59 PM.

09-01-2021, 04:28 AM	#15
ikeG Name: ikeG Title: Oughta Know Better Status: Not Here Join Date: Apr 2011 Member`s Gallery Posts: 722	That bracket is part of GMs repair kit. That is cyl 7 by the way. Sent from my SM-G960U1 using Tapatalk __________________ Isaac Griffith 'Oughta Know Better' LPS Puller https://m.facebook.com/OKBPulling/

09-01-2021, 08:07 AM	#18
weazel Name: weazel Title: 5th gear killer Status: Not Here Join Date: May 2008 Location: Mason, TX Member`s Gallery Posts: 2,252	It’s flip flopped on the duramaxes, 1 is pass side, 2 is drivers side.. __________________ 88 Chevy Half Ton/ LB7 conversion 08 Chevy 3500HD, efi, 5” exhaust

08-27-2021, 07:21 PM	#1
GreasemonkeyHd Name: GreasemonkeyHd Title: Green Behind the Ears Status: Not Here Join Date: Jan 2018 Member`s Gallery Posts: 47	Noob to the duramax diesel Just bought my first duramax truck. Only had cummins trucks and one 7.3 that I still have as my primary vehicle. It smokes and misses steadily on one cylinder. The balance rates looked like Cylinder #4 was the problem reading a 9.04, I had no CEL . It doesent tick or have any blowby whatsoever. Lb7 cab lly motor, previous owner said one of the diesel mechanics he took it to said its the ficm the other two said injectors. Fires right up every time. I put some hot shots in it and ran it in the driveway because I heard good things about it , smoke cleared almost all the way up and was running way smoother. Took it for a drive about a mile or so down the road nice and easy. Started clattering when I went to turn around. Check engine light came on and it started idling rough and clattering like a tractor. Limped it back home and it was throwing a p0201 code. Shut the truck down and let it sit for a few minutes then fired it back up. Ran smooth again with no smoke, gave it a couple Rev and immediately went back to clattering and running rough. My scanner says miss communication with ecm every time I try to clear a code even though the check engine light shuts off. Says check my plug in and ensure the vehicle is on. Seems to throw a a different injector control circuit code every time the cel comes on. Checked the harness by the alternator already and ice picked cylinders 1, 7, and 2 injector plugs

08-27-2021, 07:31 PM	#2
jasonc Name: jasonc Title: Too Much Time Status: Not Here Join Date: Nov 2009 Member`s Gallery Posts: 4,412	Needs another can of Hotshot

08-27-2021, 08:01 PM	#4
jasonc Name: jasonc Title: Too Much Time Status: Not Here Join Date: Nov 2009 Member`s Gallery Posts: 4,412	I just had a hard time reading that run on post. Break things up easier to read.

08-29-2021, 06:59 PM	#6
ikeG Name: ikeG Title: Oughta Know Better Status: Not Here Join Date: Apr 2011 Member`s Gallery Posts: 722	Swap injector 4 into another hole and read your balance rates. Sent from my SM-G960U1 using Tapatalk __________________ Isaac Griffith 'Oughta Know Better' LPS Puller https://m.facebook.com/OKBPulling/

08-30-2021, 08:06 AM	#7
DirtyMaxx03 Name: DirtyMaxx03 Title: Too Much Time Status: Not Here Join Date: May 2011 Location: San Antonio, TX Member`s Gallery Posts: 2,862	ice pick trick didnt help at all? __________________ Sean Stock 2005 LLY Last edited by DirtyMaxx03; 08-30-2021 at 08:08 AM.