Won't start after alternate fire cam

boosted4life

Member
Apr 11, 2012
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Broke a crank and had the machine shop put an alternate fire wagler 1 cam in it when rebuilding and now it will turn over, start but dies immediately. Throws a code for cam sensor performance. Double checked the wiring pin swap. Is there anything I should be looking for or is it possible the machine shop messed up the cam timing during the install?
 

boosted4life

Member
Apr 11, 2012
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If it has cam sensor signal then what? I didn't check for signal but it does start when the cam sensor is plugged in and then dies immediately. If the cam sensor is unplugged it will not even start it just cranks
 

ikeG

Oughta Know Better
Apr 19, 2011
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If it's a snap on scanner, Follow the diagnostic aid for the specific dtc. You may have to acquire wiring schematic and ohm out the cam sensor wires.

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prostreeter600

Street rodder
Jul 18, 2010
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It's been many moons ago I don't recall . I had an Edge tuner back then that allowed me to clear the codes , so if I had gotten any codes I just typically cleared them . The fact that I mentioned the Edge tuner should tell you how long ago that was . Lol . Hope you get it figured out .
 

Harbin_22

Active member
Dec 4, 2010
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Did you reuse the reluctor wheel from the broken crank? If so, was it chewed up any? When I broke mine, I had a very small knick in one tooth and my truck would do the same thing
 

boosted4life

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Apr 11, 2012
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Did you reuse the reluctor wheel from the broken crank? If so, was it chewed up any? When I broke mine, I had a very small knick in one tooth and my truck would do the same thing

I did reuse it, I'm pretty sure it was still ok but I might have to tear into it and see. Thanks.
 

boosted4life

Member
Apr 11, 2012
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Did you reuse the reluctor wheel from the broken crank? If so, was it chewed up any? When I broke mine, I had a very small knick in one tooth and my truck would do the same thing

So I was thinking about this and the machine shop used a Lb7 one piece timing gear when they built the motor, but it's an lbz, if they also used the cam tone wheel off an Lb7 would it cause this?
 

IOWA LLY

Yes, its really me
Feb 23, 2007
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So I was thinking about this and the machine shop used a Lb7 one piece timing gear when they built the motor, but it's an lbz, if they also used the cam tone wheel off an Lb7 would it cause this?



Only thing different is the crank reluctor wheel. As long as that's matched to your ECM your good.


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Awenta

Active member
Sep 28, 2014
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You're missing a tooth.

They're not interchangeable


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boosted4life

Member
Apr 11, 2012
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You're missing a tooth.

They're not interchangeable


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I was looking at a diagram for the cam and it looks like the tone wheel actually has an extra tooth on the lb7 compared to the Lbz. I'm assuming that would cause this. Again we are talking about the cam tone wheel not the crank reluctor
 

SmokeShow

Well-known member
Nov 30, 2006
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Might get one revolution of run time until the extra tooth wigs it out and kills it?

Am I remembering correctly, Pat just cut a tooth off and all was well? I guess tooth spacing doesn't matter, just number of teeth until the blank spot?
 

Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
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What do you mean by matched to the ecm? It's an lbz ecm but Lb7 timing gear

the LB7-LMM cam reluctor wheel is the same but the lb7-LLY crank wheel is different than the LBZ-LMM crank wheel. the older ones have one less tooth and a differnt bolt patter (4 bolts instead of 3). So Iowa is staying if your crank gear matches the ecm it needs to trigger correctly, that all should be good.


Now if you are getting a cam code, did you make sure the ground was hooked back up to the front of the block that hangs out just to the pass side of the front cover? did you swap cam and crank sensor or plugs accidentally? is the reluctor wheel tight on the came gear or bent up?
 

Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
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I was looking at a diagram for the cam and it looks like the tone wheel actually has an extra tooth on the lb7 compared to the Lbz. I'm assuming that would cause this. Again we are talking about the cam tone wheel not the crank reluctor

No, the cam reluctor wheels are the same across the board till the end of the LMM (far as i know, LMLs may still be the same but have not seen one personally to know).

only the crank reluctor wheel differs