Stumble after injector work

Garth

New member
Apr 2, 2025
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Alaska
Lb7 new injectors, new turbo, new fuel lines, new filter housing and filter truck idles perfect but it stumbles bad and misfires really bad under acceleration work blue white smoke
 

TheBac

Why do I keep doing this?
Staff member
Apr 19, 2008
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Mid Michigan
Moved to LB7 section. Where did you buy the injectors? What is rail pressure doing during the stumbles? Do you have a scanner or EFILive and can you log the truck when it does?
 

Garth

New member
Apr 2, 2025
7
0
1
Alaska
Moved to LB7 section. Where did you buy the injectors? What is rail pressure doing during the stumbles? Do you have a scanner or EFILive and can you log the truck when it does?
Last time I checked rail pressure was 26000 wot and all the balance rates were within spec
 

darkness

Well-known member
Jul 15, 2009
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What did you use to check all that? 26,000 is too high for an lb7 (unless you have a Lbz reg). Lb7 should be 23,200.
 

Garth

New member
Apr 2, 2025
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As far as I know no Lbz regulator
And as far as a scanner I had a Bluetooth one that connected to my phone
 

TheBac

Why do I keep doing this?
Staff member
Apr 19, 2008
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Mid Michigan
Need to log rail pressure and injectors DURING one of the stumbles/misfires.
Probably multiple bad injectors, but its a total guess without more info.
Remember, we arent standing there next to you.
 

Garth

New member
Apr 2, 2025
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0
1
Alaska
Need to log rail pressure and injectors DURING one of the stumbles/misfires.
Probably multiple bad injectors, but its a total guess without more info.
Remember, we arent standing there next to you.
If there is air trapped in the low side and possibly the ficm or the high side would it make the truck run like shit
 

JoshH

Daggum farm truck
Staff member
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Feb 14, 2007
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Do you know what brand you purchased from them? I just checked the website and was surprised to see they carry Bosch reman injectors at a fairly reasonable price.
 

JoshH

Daggum farm truck
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Feb 14, 2007
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What is the history of the truck? Was it running and driving prior to the injector work, or had it been sitting for an extended period of time? I wonder if you have some bad fuel causing problems. I would verify you have good, clean fuel in the tank, and use your scan tool to verify the truck is building proper fuel rail pressure under load. To answer your earlier question, air isn't generally trapped in the low side, but if you have something allowing air to get into the low side, I have seen that cause symptoms similar to what you are describing. In my case, it was the WIF sensor on the bottom of the fuel filter.
 

2004LB7

Super Moderator
Staff member
Dec 15, 2010
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Harness connectors at the injectors, the nuts, if loose can do some weird stuff too. Stumbling, misfiring, smoke, etc. and since recent work was done I double check those connections. And make sure none got swapped around to the wrong injector