Help LBZ no start

[modpcm]

Hi Guys,

I need help on a 2007 LBZ, I want to use the EFI Scantool but never did that before for what I need. I'm quite familiar with the TuneTool and only did diesel tune in the past.I need some guidelines to setup properly for the following situation.

2007 LBZ auto pickup Classic , crash and rollover, severely damaged and repair by a independant shop , the condition is a crank no start condition with no dtc's at all on any module on the truck. The engine won't start because there's no signal at any injectors , I scope the circuit and they're all dead . All the parameters on the Tech2 , fuel pressure, rpm, air ,coolant temp, maf are normals. No theft light or dtc. I can read data on all module ,ecm.tcm,ipc,ebcm,tccm,gcm, so my class2 and HS CAN bus are ok and again no U codes set. Mechanically we know the engine is ok , we feed it at the air induction and the engine run at 1000 rpm.

The ecm was replaced and flash with the VATS disabled, and all circuit at the ecm check for pin grip and voltage drop. So I'm at this point of beliving the ecm is commanding a no fuel situation if that is possible during a crank event.

I need to know what PIDS should I look too for having a no pulse width condition.

Any help is appreciated

modpcm

[Sparky8370]

Hi Guys,

I need help on a 2007 LBZ, I want to use the EFI Scantool but never did that before for what I need. I'm quite familiar with the TuneTool and only did diesel tune in the past.I need some guidelines to setup properly for the following situation.

2007 LBZ auto pickup Classic , crash and rollover, severely damaged and repair by a independant shop , the condition is a crank no start condition with no dtc's at all on any module on the truck. The engine won't start because there's no signal at any injectors , I scope the circuit and they're all dead . All the parameters on the Tech2 , fuel pressure, rpm, air ,coolant temp, maf are normals. No theft light or dtc. I can read data on all module ,ecm.tcm,ipc,ebcm,tccm,gcm, so my class2 and HS CAN bus are ok and again no U codes set. Mechanically we know the engine is ok , we feed it at the air induction and the engine run at 1000 rpm.

The ecm was replaced and flash with the VATS disabled, and all circuit at the ecm check for pin grip and voltage drop. So I'm at this point of beliving the ecm is commanding a no fuel situation if that is possible during a crank event.

I need to know what PIDS should I look too for having a no pulse width condition.

Any help is appreciated

modpcm
Well it can't be that if you are getting it to run by feeding it starting fluid. I am assuming that's what you meant when you said "... we feed it at the air induction and the engine run at 1000 rpm." because it is no longer in a cranking state when you have it running.
I am assuming the LBZ has a FICM and I didn't see that you mentioned that as one you checked. You should probably check that out.

[Sparky8370]

Nevermind, I just looked it up and the LBZ does not have a FICM. Scratch that idea.

Although I doubt it's your problem for reasons stated above, I did look up a cranking table in a LBZ tune (B1127). It references a tq value for a given ECT and RPM, and then the ECM looks at B1102 for that tq value and commands the amount of fuel for that tq value while cranking. In B1127 RPM columns 1100 and up show no value. Maybe check the RPM PID when cranking to see if the computer thinks the RPMs are over 1100???? Just trying to through ideas out there, even if they are crazy.

[modpcm]

Thanks Sparky8370 for your comments, I will visit the repair shop next week, the truck is at 6 hours of driving from my place near a huge power dam , so I'm packing my tools and will let you.

modpcm

[Sparky8370]

You should post this same thing on www.dieseltowingresource.com and dieselplace. Doesn't seem to be getting too much action here. Lots of people on those sites that can really help a lot.

[GMPX]

Correct Sparky, posts on EFILive should be related closer to software rather than what this is about. Many users on those sites deal with this sort of stuff day in day out.

[1markbianchi]

hi have same problem with o6 lbz no start after rebuild did you ever figure it out

[comnrailpwr]

hi have same problem with o6 lbz no start after rebuild did you ever figure it out

Im sure he did over 4 years ago when he made this thread. Maybe try the site's that were posted.

[1markbianchi]

sorry guys im a new member not sure exactly how these forums work but I need help and im trying to contact modpcm I did reply on his post again sorry im just trying to figure this out and none of the other forums have been much help thanks

[modpcm]

Hi, if I recall correctly, the issue was no injectors pulse at all, but the engine was "running" if we feed it with something (brake cleaner maybe) . Anyway the problem was the camshaft sensor signal was not sync with the crankshaft sensor signal. I don't know the technical reason why no dtc set but after disassembling the engine we found the cam gear off or not timed ok. The diagnostic was by using a scope and monitoring a good running engine during a crank event and monitoring both crank and cam signal, I can't recall exactly how the 2 signal sync , but it was obvious that the number of tooth was different from the good engine and the problem one.

Whish that could help you

modpcm

[1markbianchi]

thanks for the info modpcm I will pull front cover and check everything today its just odd the tech 2 says that cam and crank are synced but sometimes scanners are only as good as the person using them so im thinking I must have made a mistake on the mechanical end but thanks again for responding

[modpcm]

thanks for the info modpcm I will pull front cover and check everything today its just odd the tech 2 says that cam and crank are synced but sometimes scanners are only as good as the person using them so im thinking I must have made a mistake on the mechanical end but thanks again for responding

The front cover job takes a lots of time, try to have access to a scope dual trace , in 30 minutes you will know if your're sync .

[1markbianchi]

Found problem broken keyway on oil pump gear got in a hurry and did a no no and used a impact on oil pump gear first 6.6 build bet I fond make that mistake again I really appreciate you responding and giving the info thanks mark