LB7: built lb7 wiring/injector issue help needed

lmmcbrown0917

lmmcbrown0917

Member
Oct 13, 2013
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North Carolina
i got the lb7 in my sig put back together with the built motor, I'm running into some issues. the truck will run but only on four injectors.

I'm getting P0201, P0206, P0207, P1261

i have already pulled the passenger side valve cover to inspect the injector harness and they seem good, i also swapped the wires over on each injector with no change in codes or how it runs.

the truck also has a AF cam from empire, not sure if that makes a difference with the injectors,

ANY help is greatly appreciated. :confused:
 
rgullett83

rgullett83

Active member
Oct 27, 2008
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Have you double checked the harness where you swapped wires with the firing order change?

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lmmcbrown0917

lmmcbrown0917

Member
Oct 13, 2013
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North Carolina
rgullett83 said:
Have you double checked the harness where you swapped wires with the firing order change?

Sent from my SM-G900V using Tapatalk
Click to expand...

yes checked them all over very well. the truck was running last week with the harness the way it is now. the motor was pulled for a freeze plug issue then re installed today.
 
clrussell

clrussell

pro-procrastinator
Sep 23, 2013
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Tighten the pins in the main harness cinnectir and the ficm connectors
 
dirtydmax

dirtydmax

<---up shit creek
Sep 1, 2013
1,091
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muskoka,Ont Canada
Had the same happen and after swapping inj harness twice I found a short on the metal holddown bracket knocking the bank out . frustrating I know but keep at it.
 
lmmcbrown0917

lmmcbrown0917

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Oct 13, 2013
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dirtydmax said:
Had the same happen and after swapping inj harness twice I found a short on the metal holddown bracket knocking the bank out . frustrating I know but keep at it.
Click to expand...

whats confusing me is its throwing 1,6,7. if it were throwing a bank wouldn't it be one whole side together?

at first it was throwing #4 also but it just went away on its own?
 
dirtydmax

dirtydmax

<---up shit creek
Sep 1, 2013
1,091
4
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46
muskoka,Ont Canada
lmmcbrown0917 said:
whats confusing me is its throwing 1,6,7. if it were throwing a bank wouldn't it be one whole side together?

at first it was throwing #4 also but it just went away on its own?
Click to expand...
That's what I thought when mine coded out...only 3 cylinders showed up but I did find the break in the insulation exposing the wire.I chased it for a week pulling those damn covers.
 
MAXX IT OUT

MAXX IT OUT

<<<IT WORKS
Mar 1, 2013
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Des Moines, Iowa
Both times I had this problem it was a hard parts problem. First time it was a new engine and the lash nut never got torqued or something like that and it lost the Rocker bridge. The second time it busted a injector wire stud.
 
lmmcbrown0917

lmmcbrown0917

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Oct 13, 2013
159
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North Carolina
MAXX IT OUT said:
Both times I had this problem it was a hard parts problem. First time it was a new engine and the lash nut never got torqued or something like that and it lost the Rocker bridge. The second time it busted a injector wire stud.
Click to expand...

i dont believe its mechanical, i have both valve cover off and everything underneath is in-tact from what i can tell.

I'm out of ideas..:confused:
 
DAVe3283

DAVe3283

Heavy & Slow
Sep 3, 2009
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Boise, ID, USA
Since you have the covers off, now is a good time to use a digital multi-meter to verify the injector harness looks good. I know you said it ran fine on this harness before, but I would tripple-check the injector harnesses. Make sure there is no connection from any pin to ground, and the resistance at the plug is the same as directly across the injector terminals, and maybe have a friend wiggle everything around while you test to see if there is an intermittent short?

dirtydmax said:
WY hold down had a slight up word bend and only when the top cover went on it would ground out
Click to expand...
That's a good idea. You could try starting it with the valve covers off and see if it runs fine. Narrow down the possibilities. The injector harness might short when pinched by the valve cover where it goes through.
 
lmmcbrown0917

lmmcbrown0917

Member
Oct 13, 2013
159
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North Carolina
dirtydmax said:
WY hold down had a slight up word bend and only when the top cover went on it would ground out
Click to expand...

Well I pulled the driver side cover and hooked up everything and fired the truck with top cover off and all the codes were gone and it was definitely firing on all 8. I'm guessing one of the driver died harnesses are grounding out on the cover, I can't see any really bare spots on the wires but there are some small cuts where the plastic clams were.
 
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