05 6.0 losing ckp signal and sync

cbriggs · January 7, 2010

Hey guys, I have an 05 6.0, 40k on it. Starts and idles great. Runs good cold, once warmed up it loses ckp signal at around 2600 rpm. Signal goes erratic jumping from 1000 to 5000 rpm, as read on the ids and the tach. Loses sync at same time. engine coughs and surges and smokes.( almost like a stuck egr valve). I have tried a new ckp sensor , tested harness - resistance ok, load tests ok,no shorts to pwr or grnd, Trigger wheel is tight on crank, modified a sensor to change sensor air gap, disconnected alternator and gpcm, none of which helped the concern. I have backprobed ckp wires at pcm while concern is happening and ac voltage remains constant ( my vantage wont sample short enough time to see waveform, havent had time to set up vmm yet). The really weird thing is, if truck is left outside in the cold (-10 to -20 c) it runs great for a while, until it warms up good (30 minutes or so). If left in the shop overnight concern will happen immediately after startup. Also note; I did a bed plate reseal on this truck about 1000km, 4 weeks ago and thuroughly shampooed engine. ( as i do on all 6.0 repairs) I am thinking water penetration into something, when frozen it is ok, but once it thaws is it fuking with something. Has anyone ever seen water penetrate one of these pcms?

Mbl35 · January 7, 2010

I had to replace one for coolant intrusion. I would try a ficm.

I had one sunday night, the detailer tried to start it, it would run for a second and shut. The batteries were fully charged and the ficm power was at 30v. I took a ficm out of a unit in the bodyshop that i recently put in and swaped it in, she started rite up, i ran the moniters and all ok. This is also an 05.

GregKneupper · January 7, 2010

I had one that had a bad pcm in it causing that concern. You could tap on the case and the engine would sputter for a brief second.

Bruce Amacker · January 7, 2010

I commend you on doing a great job of logical diagnostics, as your thought process is virtually identical to what I'd have done. I might suggest using a CKP overlay harness to rule out freaky EMI/RFI problems, and checking the CKP/CKPO waveforms with a scope to see exactly what's acting up when the problem occurs. While I had my scope out, I'd probably look at CMP and CMPO, as well as powers and grounds, just in case you've got an odd base electrical problem. I'm with the others thinking along the module line, but wouldn't rule out a harness or electrical problem. Please keep us posted on what you find with this beast.

Good Luck!

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Aaron · January 7, 2010

I just went through this. Try cutting the big O-ring off the cam sensor (closest to the connector) and putting it back in. If that allows it to run, check for rust buildup in the CKP bore.

Keith Browning · January 7, 2010

Something isn't quite right here. I had a truck that would start cold once a day but after that it would not fire, no sync. It would fire with an alternate fuel source. Long story short, the CMP sensor on the left was deformed by rust buildup on the block that pushed the sensor tip away from the block causing a weak signal.

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FYI: The engine does not need to be running to scope the CMP and CKP sensor signals.

Aaron · January 8, 2010

^^ Yah, what he said. Mine looked like that too.

Jeff Clyde · January 8, 2010

Have had quite a few like that myself, unfortunately alot of them end up coming out in pieces.

Aaron · January 8, 2010

Wow....looks like flat rate reading.

I was talking about the CMP, and Chris was talking about the CKP...

My bad!

cbriggs · January 8, 2010

OK, so after a few sleepless hours last night, i came to the conclusion that water was somewhere it shouldnt be, explaining the fact that it runs like a top cold, (started at -24`c this am) but shits the bed when warm. So i started it this morning, ran it for five minutes to confirm it runs great. Put heat gun on pcm and warmed it up, still runs great. Put heat gun to ficm, still runs great. Put heat gun to ckp sensor, instantly concern re-appeared. Pulled rh side of harness out for better view and there it was, moisture in the connector for the ckp sensor. Cleaned connector out and dried, filled with electrical grease, reinstalled and voila, runs like a top. I also figured out why i couldnt view a waveform on my vantage, apparantly i need to rtfm once in a while, i forgot how to use it.

Oh yeah, it was throwing a p0336 and p0341 as well.

Jim Warman · January 9, 2010

There you go.... Canajuns know it is "voila" rather than "walla".

Good catch with the heat gun (my first experience was in about 1985 with a TBI Nissan pick up... I used my loving brides blow drier to spot a temp sensitive concern).

Bruce... when you overlay a harness like this (being we are dealing with a VRS sensor) do you twist the wire pair and overlay both halves or what? Reason I ask is because I'm not a big fan of overlaying harnesses as a repair.

I have come to the realization that, sometimes, my biggest enemy is me...

Why is it that you can proof read something 400 times... but you can't see the typo until you click <SUBMIT>?

Aaron · January 9, 2010

I've (personally) only overlaid a harness as a testing procedure. I have a bunch of 6.0 harnesses kicking around and I rape all the connectors and pins out of the pcm side. So, basically, I de-pin the PCM connector at the circuit in question, put my "test pins" in it and overlay the circuit to whereever I'm going. It is sometimes a lot of work, but it is a good harness eliminator and you don't spread all the pins in the hard shell.

sixturbosix · January 10, 2010

Sep 8, 2009: Diesel Cam Timing available on IDS release 63

A new oscilloscope tool, 'Diesel Cam Timing', is available on IDS release 63. This tool monitors the CKP and CMP signals of 6.0L diesel engines while cranking and provides help and instructions to verify proper base engine timing and sensor signal integrity.

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Is this what you guys use when checking the signal of the sensors?I saw this on a tsb a while back but have never used it.

cbriggs · January 10, 2010

Ya, that was going to be my next venture, but our vmm has never been used yet, as i have my own dso (snap on vantage), and didnt feel like setting it all up if i didnt have to.