Help with smoking LMM??

J

jgriffn

New member
Sep 4, 2014
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I have an 07.5 LMM with 5" straight pipe, DPF delete, S&B CAI, EGR blocker plate, EFI live tuning and edge for gauges. I was getting onto the highway pulling my boat and about the time I hit 70 mph I noticed a loss of power and looked back and smoke was blowing out the exhaust really badly, mostly whitish colored smoke. I pulled over and the truck was still running but idled a little lopey. I drove slow to get off the highway and it was still smoking pretty good. I didn't see any oil or coolant in the engine compartment or on the ground. After unhooking the boat I drove it a couple miles to the house and without the load driving about the 30 the smoke wasn't as bad but when I got to the house then it was still smoking and idling rough. I shut the truck off and it restarted fine. I pulled up the injector balance rates and have pics below. Do you think injectors are the problem or is it probably motor related since it happened real bad all the sudden.
Here is idle in neutral.

Here is idle in drive with the brake on.

Just wondering what else I need to check before assuming its just an injector problem.
Thanks for any responses.
 
J

jgriffn

New member
Sep 4, 2014
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I don't know how high they were when happened, I was on the light tow tune. My tunes are from duramaxtuner.
 
Robby Avery

Robby Avery

GM TECH @ FENDER GMC
Jul 31, 2008
820
2
18
Norman Park, Georgia
Injector # 7 looks to be a little high gm spec is +/- 6 over or under is signs that either the injector has taken a turn for the worst or you by chance have a connector issue at connector c107 or c108 which are the two main engine harness connectors that the edge ties into on top drive side of the engine did a check engine light pop up after the smoke started or just all of the sudden happen
 
andy-stevenson

andy-stevenson

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Jul 7, 2013
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Robby Avery said:
Injector # 7 looks to be a little high gm spec is +/- 6 over or under is signs that either the injector has taken a turn for the worst or you by chance have a connector issue at connector c107 or c108 which are the two main engine harness connectors that the edge ties into on top drive side of the engine did a check engine light pop up after the smoke started or just all of the sudden happen
Click to expand...

Balance rates don't tell you 100% if it's an injector, just that somethings off in that cylinder and the truck is compensating by adding or removing fuel...

Also he said the edge is just being used for gauges so I'm assuming it plugs into the ObdII under the dash?

I'd do a compression test before replacing injectors.
 
J

jgriffn

New member
Sep 4, 2014
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Yeah I had my girlfriend take the oil fill cap off and start it and it is puffing smoke out, so probably not an injector issue and I'll be doing a compression check when I get home.
 
H

Hot COCOAL

May the farce be with you
Jun 9, 2012
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andy-stevenson said:
Balance rates don't tell you 100% if it's an injector, just that somethings off in that cylinder and the truck is compensating by adding or removing fuel...

Also he said the edge is just being used for gauges so I'm assuming it plugs into the ObdII under the dash?

I'd do a compression test before replacing injectors.
Click to expand...

Good info!
It's possible that you cracked a piston :(
It is possible the #7injector is getting bad too, I wouldn't think that it would make white smoke and a lopey idle tho...

Start with a compression test, then if that checks out do a leak down test on the heads and have the injectors checked...
 
J

jgriffn

New member
Sep 4, 2014
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Yeah I will be doing a compression check first thing but I won't be home for 2 more weeks so I will have to wait till then to be sure.
 
duallydmax06

duallydmax06

six six
Aug 26, 2014
53
0
0
Any updates? Miles on motor? What happened? What did you do full rebuild? I hate when threads like this die
 
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