Could use some help! ? Injectors

[michiganmax]

Hi I am new to the forum world and having a Duramax. I just picked up a 01 lb7 Duramax. The motor has a knocking sound that shows up when you take off. It is there when you give it gas. It sounds like it is coming from the drivers side. I have had it go away while driving it, then next time I am in it, it's back. The truck runs smooth at an idle with a little smoke out the tail pipe. I get 17 mpg on the hwy. not sure if that's good or bad. The truck is a ext. cab 4x4. I previously owned a 12v Cummins, so I am used to a loud motor. But I don't think this motor is supposed to make that noise. So I am not sure if it is a injector or a lifter nose. If anybody out there could give me some input, I would really appreciate it. Thank you


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[Muff]

Hi I am new to the forum world and having a Duramax. I just picked up a 01 lb7 Duramax. The motor has a knocking sound that shows up when you take off. It is there when you give it gas. It sounds like it is coming from the drivers side. I have had it go away while driving it, then next time I am in it, it's back. The truck runs smooth at an idle with a little smoke out the tail pipe. I get 17 mpg on the hwy. not sure if that's good or bad. The truck is a ext. cab 4x4. I previously owned a 12v Cummings, so I am used to a loud motor. But I don't think this motor is supposed to make that noise. So I am not sure if it is a injector or a lifter nose. If anybody out there could give me some input, I would really appreciate it. Thank you


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Really you spelled It Cummings?

 

[cdprayor]

Really you spelled It Cummings?

:spit:

 

[michiganmax]

That's what auto correct will do to ya. Fixed better?


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[DAVe3283]

Does it smoke white/grey when you take off, especially after idling a while?

This sounds like it could be the classic LB7 bad injector problem.

17 MPG on the highway is in the ballpark. Depending on the tires, wheels, lift (if any), and tune (if any), that could be anywhere from great to below average mileage.

 

[TheBac]

It "sounds" like a stuck or bad injector to me, but my "long-range diagnostic hearing" isnt working right now. :roflmao:

 

[michiganmax]

I see a little white smoke when it sits idling. When I take off its hard to see, I think I see a little white smoke once and a while. The tires on the the truck are 245/75/r16, no lift and no tune, not yet.

If it is a injector would it come and go? I have noticed it will go away for a bit when the motor is nice and warm.


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[DAVe3283]

Normally with injectors it gets worse when warm, not better.

It could still be an injector, but it is hard to say for sure when diagnosing remotely. You can get a scan tool and check the balance rates and see if they are all in spec.

 

[Brent@LDS]

I would agree get your balance rates checked.

 

[michiganmax]

Sounds like I should get my balance rates checked. Now with the balance rates, is the higher the number better or lower? Or do they fluctuate?


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[Brent@LDS]

Spec is -/+4 in park up to operating temp.

 

[michiganmax]

The injectors that are in the truck are Bosch. Should I stick with Bosch or is there a cheaper one that will do the same? They would be stock. I do plan on getting a tuner for it. What are your thoughts. I appreciate all the advice you all have given me so far. Thank you


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[TheBac]

Stick with Bosch remans. Merchant Auto in Holland has them. LDS has a good reputation for injectors, too.

Do the proper tests first to make sure it is injectors, though.

 

[WI Huck]

The white smoke at idle is from a cold cylinder. When an injector wears out the spray coming out of the nozzle tip is more of a stream than a mist. It takes a higher temperature to burn the stream of fuel than the mist. Think of it like a camp fire. You need to light the small sticks and then when it gets hot you can add the logs. When the RPM goes up the cylinder gets hotter and burns the fuel, and the smoke goes away.

We are a Bosch authorized dealer. Give us a look.

 

[Brent@LDS]

OEM Bosch injectors would be the ONLY injectors I would get if you need them. Let us know if we can help.

 

[michiganmax]

Can a GM scanner tell me what injector is not right? Or will I have to go to a dealership? I don't have the funds to pick up a EFI Live. I don't know anybody that has one.


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[Brent@LDS]

I can't say for sure but im going to guess probably not with that scanner.

 

[TheBac]

Can a GM scanner tell me what injector is not right? Or will I have to go to a dealership? I don't have the funds to pick up a EFI Live. I don't know anybody that has one.


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Where do you live?

 

[michiganmax]

I live in Traverse City, I do travel to Big Rapids and Cedar Springs every other weekend.

 

[michiganmax]

So I had my flow rates done. #3 & #5 injector was high. I bought 2 new Bosch injectors, all I could afford.

So my question is, what are the odds that after pulling the motor down and back together, the other two injectors would still be good?
I did pull the 2 good injectors and cleaned them off, put new o rings on them.


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