Cam sensor issues, wiring, or wrong reluctor wheel can cause a VATS like no start

[Alvin]

This is just a PSA.

I've had several GEN 4's crank and immediately die because of cam sensor issues/reluctor wheel issues/cam wiring. GEN 3's will typcially run fine. They will just start funny (out of time, equal chance of being on wrong TDC)

This is the latest one from this week.

A old customer decided to do his own work and install his own engine. He says he got it started but it immediately caught on fire. FAST intake and fuel rails was the cause there. It ruined large parts of the harness. We looked around for a solid week for a replacement harness. Couldn't find one. A lot of GM parts houses would say it's in stock but when you called it wasn't.

We do have a full time wiring/harness employee for our products and we stock just about every connector on these things so we repaired his original harness.

We get the car back together and it will fire and immediately die. I immediately suspect we made a error repairing the harness.. but also have had experience with cam sensor issues doing the same thing. WITH NO DTC. Just with a gut feeling we set out on replacing the cam sensor. It will not come out of the timing cover. Which I've seen before. The plastic swells up and have to be broken to get out. So we pull the timing cover off. That's when we found someone sold this guy a engine with a 58 x crank and a 1x cam gear.

IMG_2111_1.jpg

[RoninDusette]

Anything with an e40 ecu will have want a 24x reluctor wheel, and all tb and tbss motors have the same, if I am not mistaken. There are very few engines in gen iv that have a 24x wheel, most of the time people will pull from a tb or tbss. If using in a gen iii, you should be able to change between high/low count reluctor in the System tab, or if needed, you can get one of those stupid little lingenfelter boxes, but stand warned.... they break SO easily. I have never seen one make it over a year, and they are hundreds of dollars. They are not shielded as well (or at all in some places) as they are advertised, if wired wrong ONCE, they fry, and if you don't route the sensor wires to and from it carefully, it will pick up interference. I wish someone would make a competing device that actually isn't as fragile as an premature newborn in a faberge-egg basket, but yeah...

A good way to tell if you are having the issue the OP mentions, is you will read zero RPM in your scanner. May not throw a code (never seen one throw a code for mismatched ecu/calibration and reluctor), but it's a good indicator if you read zero cam/crank pulse or RPM.

[blindsquirrel]

It's not strictly a Gen 4 thing. Through 2007 the service manual still has the old language: "If the crankshaft position (CKP) pulses are lost, the engine will not run. The loss of a camshaft position (CMP) signal may result in a longer crank time, since the ECM cannot determine which stroke the pistons are on" - the same as it had been all the way back to the Gen3s. In 2008 that is no longer present.

2007 Corvette Electronic Ignition Description - Document ID_ 1604283.pdf
2008 Corvette Electronic Ignition Description - Document ID_ 1958455.pdf

Disclaimer: Always the possibility that GM didn't correctly update 2006-2007 service manuals with the new description for the 58x/4x systems. Or, in 2008 they stripped down the description to remove things that were still applicable. The 2008-up D&O seems very dumbed-down compared to the earlier versions.

Another thing to note, if you look at the diag pages for CMP codes, they ask you to crank the engine for 30 seconds before checking for codes. Apparently they will not set without extended, continuous cranking. So lack of codes after a normal length crank-no-start may not be the whole story.

[bignperformance]

This is just a PSA.

I've had several GEN 4's crank and immediately die because of cam sensor issues/reluctor wheel issues/cam wiring. GEN 3's will typcially run fine. They will just start funny (out of time, equal chance of being on wrong TDC)

This is the latest one from this week.

A old customer decided to do his own work and install his own engine. He says he got it started but it immediately caught on fire. FAST intake and fuel rails was the cause there. It ruined large parts of the harness. We looked around for a solid week for a replacement harness. Couldn't find one. A lot of GM parts houses would say it's in stock but when you called it wasn't.

We do have a full time wiring/harness employee for our products and we stock just about every connector on these things so we repaired his original harness.

We get the car back together and it will fire and immediately die. I immediately suspect we made a error repairing the harness.. but also have had experience with cam sensor issues doing the same thing. WITH NO DTC. Just with a gut feeling we set out on replacing the cam sensor. It will not come out of the timing cover. Which I've seen before. The plastic swells up and have to be broken to get out. So we pull the timing cover off. That's when we found someone sold this guy a engine with a 58 x crank and a 1x cam gear.

IMG_2111_1.jpg

[bignperformance]

new motor swap under warrant. disabled dod in tune. is giving cam pos sensor code. replaced sensor upon install. possible bad sensor? truck is all stock besides turning off dod. thanks for any help in advance!

[blindsquirrel]

new motor swap under warrant. disabled dod in tune. is giving cam pos sensor code. replaced sensor upon install. possible bad sensor? truck is all stock besides turning off dod. thanks for any help in advance!

No files posted, no DTC number given, tacked onto a post that is general info not pinpoint troubleshooting. Start your own thread about your problem with all the relevant info and your tune file & log file showing it crank and not start. You're welcome in advance.