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This is my first post on this site, I've read through some posts trying to find a match to my problem and have decided to just start a thread about my issue.
I've done an LS Swap into a 2007 Porsche 997. hopefully this isn't a disqualifier for help.
- new GM crate gen 4 ls3 with hot cam option. All components on the engine are stock from GM.
- I was getting a cam crank sync unknown encoder error which was solved by adding shielded wires for the cam and crank sensors, well mostly solved apparently. before installing the shielded wires i would get the cam crank sync unknown error, after installing the shielded wires the encoder count will be 1-5 and hold steady
- I'm using a ProEFI 112 ECU and wiring harness, tuned by a ProEFI expert tuner. The tune wasn't fully dialed in due to the cam crank sync unknown error.
- I just pulled the cam crank signals on an o-scope and it looks good to me (but I'm not an expert)
the car will start and idle (roughly), heavy gas smell, after idling for 10-15 minutes something is causing a crank signal loss code, the car shuts down. it'll start back up, but will stall again within a few minutes.
I let the car sit and cool for several hours and i can repeat this cycle.
I don't understand why the engine would run for a period of time with no encoder count increases while idling and then have the CnkLossFault after ~15 minutes of idle.
i need to get this fixed before i can get my tuner reengaged.
OK. I once had a P0336 crank sensor code. This code would trigger when the coolant reached 186° due to thermal expansion. But the crank end play checked. 005"-.007"!! This was due to a pinchbolt the C5 A4 Vettes use to clamp the flexplate firmly to the input shaft splines on the torque tube. So, unless you loosen that pinchbolt, you are basically checking the end play of the torque tube, NOT the crank. There is a special procedure required when installing the assembly. Without performing it, your thrust bearing can wear out prematurely. When I loosened that bolt, my crank end play measured almost .030"!!! Yeah, it was
Last edited by grinder11; Feb 15, 2025 at 05:37 PM.
Hopefully the crank end play is OK, especially since it is a brand new crate engine.
How did you ground the shielding? I would ground it only at the ECU and not at the engine; if you ground it both place, you might get current through it when e.g. the cooling fans turn on. In other words, the shield should never be a ground return.
You might consider trying a different crank sensor. Be careful buying one as many cheap "Genuine AcDelco" on Amazon are fakes. If on Amazon and the seller is Amazon itself, it likely is Genuine; however if the seller is e.g. "BestPriceAuto", stay away. Or buy the sensor at Summit Racing, local auto store or dealer. If there is some thermal expansion, a different sensor might handle it better.
HI, i have the 2 wires grounded to a threaded bracket mount point post inside of the passenger compartment near the ECU which will be mounted under the rear seat. I replaced the crank sensor already and saw an improvement afterwards. i got the sensor from o'reillys auto store near me.
AC Delco has an official store on Amazon. It's the only place I buy real AC Delco stuff. And it's a lot cheaper than the dealers parts counter.
Great to know!
I recall a thread here where someone included pictures of a genuine AcDelco part in a clear bag with logo and a fake one. The printed bag logo on the fake one was just a tiny bit different! Despicable. These people should be rounded up and drowned in the East China Sea.
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crank sensor losing signal 
