lb7 injectors loud under load and completely quiet once I hit 2900rpm ...???

[rcfreak24]

I have a 03 lb7. Starts awesome hot or cold no missing no smoke idles great runs good. Under load the injectors are loud but once I hit 2900 rpm the sound is gone completely out doesn't fade out it just stops like you flipped a switch
..

Does anyone have any idea's? It is annoying even with 5" exhaust and radio on you can still hear them ticking on the interstate.

No fuel in the oil either. ..


The truck has no tuning.

 

[TheBac]

Are they the original injectors or rebuilts? Miles on truck?

 

[Hot COCOAL]

Almost sounds like pilot timing....not sure what the LB7's did, when it came on and shut off

That's normal for the most part, maybe it's an indication of dirty injectors, or possibly a dirty fuel filter?

When's the last time you changed the fuel filter, or ran a good fuel system/injector cleaner like standyne or power labs clean diesel?

Where are the lb7 guys???

Allot of these nuts run 2-stroke or trans fluid or motor oil and all sorts of crud in their tanks with fine results, personally I run standyne, power labs and schaffers, separately of course.

 

[rcfreak24]

I'm not sure the history on the injectors but the truck was owned by the government since new. It has 190k on it now. I have put about 4k miles on it.

I put fuel additive in every time I get diesel. Which has made them a tad quieter. I also added a fass 150 titanium and put a new filter on the engine.

The truck runs great starts perfect even when 10 degrees out neve misses or smokes and all balance rates are in spec.

They are noisy and right at 2900 rpm they get completely quiet but the truck still runs and pulls just as good. ..

By the way I use Schaffer oil and additive for the fuel.

 

[DIESELMAFIAPER.LB7]

Guess I'm a nut for using 2 stroke sound normal to me I believe the amount of pilot decrease before that rpm but I don't have my laptop in front of me. get you a nice CTS monitor and start watching things like rail maybe it's holding more then desired rail pressure till it gets up to that rpm....

 

[Hot COCOAL]

Guess I'm a nut for using 2 stroke sound normal to me I believe the amount of pilot decrease before that rpm but I don't have my laptop in front of me. get you a nice CTS monitor and start watching things like rail maybe it's holding more then desired rail pressure till it gets up to that rpm....

Lol, I meant that in the best of taste :angel:

That's the dark side of diesels to me, I'm afraid of the dark....:roflmao:

Lol, So yeah, you're a nut...cuz I'm afraid to do it :hug:

 

[gmduramax]

How much PSI is the lift pump putting out?

 

[03spoolindmax]

I run the walmart 2 stroke oil mixed with diesel Kleen. My injectors always seemed noisey even after the dealer replaced them. When I removed the lift pump before I sold the truck. The injectors were way more noticeable. All injectors were within spec too.

 

[rcfreak24]

They were loud before the lift pump. So I installed it just in case. They did get quieter a little with fuel treatment. I may try some 2 stroke oil.

It's just annoying. And when I start the lb7 lly lbz lmm at work all of them are quiet. Can not hardly hear the injectors. Mine is obvious.... sounds like a Damn sbc with loose rockers lol

 

[gmduramax]

What is your rail pressure at idle?

 

[DIESELMAFIAPER.LB7]

What is your rail pressure at idle?

X2

 

[rcfreak24]

I'll check with scanner. They are quiet at idle just under load or like above 1300 rpm you can hear them

 

[rcfreak24]

Will this be of any use to yall

 

[Bustedknuckles]

Curious to see what you find. My trucks the same way. Super loud tick under load!

Sent from my SPH-L720 using Tapatalk

 

[yellowchevy]

I would say the valves need to be adjusted but if they just stop at 2900rpms I could be wrong.

Do you know for sure it's never been tuned?

Yellowchevy

 

[PhilsLB7]

Mine does the same thing under load. More noticeable between 1500 and 2000 RPM. Less noticeable as it goes above 2000. I was told this is normal for LB7's but I just don't remember it being this loud, even with 2 stroke or other fuel additive. I'm going to try the GM fuel injector/Upper Cylinder cleaner sometime to see if it helps. For now just turn the radio up louder.

 

[rcfreak24]

Definitely not the valves. It stops like you flipped a switch around 2900 rpm.

Truck was government owned till I got it so it was never tuned. 100% stock

 

[rcfreak24]

I turn the radio up louder also but with the baby in the truck I can't always do that...

 

[Bustedknuckles]

Mine does the same thing under load. More noticeable between 1500 and 2000 RPM. Less noticeable as it goes above 2000. I was told this is normal for LB7's but I just don't remember it being this loud, even with 2 stroke or other fuel additive. I'm going to try the GM fuel injector/Upper Cylinder cleaner sometime to see if it helps. For now just turn the radio up louder.

I did that. Helped for like a day. I'm pretty sure its injectors but everything is good other than the noise. Which even though its not that loud drives me NUTS.

Sent from my SPH-L720 using Tapatalk

 

[rcfreak24]

I'm glad other people know what I'm talking about. It's just plain annoying. ...