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cmp to ckp sync

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hey guys i got a late build 2004 f550 cust brought in for stumbling says it acts like itwants to die and is worse when hot pulled codes p0341 p0275 p0404 p0528 p2614 p2617 ran oasis maessages said to diag drivability before cmp/ckp codes i also checked the usual locations for chafescannot see any when i went to do a power balance with pds would not let me said ckp to cmp syncronization i guess my question is has anyone run into this and is there any other chafe points that anyone has found this truck has 87000 miles

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I have had 2 that gave cmp/ckp synch error codes. The first one was

a wiped crank thrust brg that let the crank walk forward and back causing the codes. The second ( and way harder to find..) was a loose crank trigger wheel on the front of the crank.

I would check the rpm pid while running and see if it looks erratic, and see if you can move the crank front to rear.hth

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  • 6 months later...

I was doing a little searching for a sync problem and found these posts, doesn't look good for tech working on truck.

 

It's a late '04 in which he just installed a short block for a bed plate sealing problem. Truck ran fine before but now the rpm pid is erratic the truck stumbles while driving and the sync pid toggles yes to no.

 

Anyone had this happen on replacement engines?

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ive only had one do that to me only at 55-70mph and thank god keith helped with it on here and told me to turn SYNC and FICM sync into a bar graph and found it erratic.....replaced cam, crank sensors and wiring harness, fixed it. Hotline gave me killer ways to check it with the Scope on IDS to check if it was a trigger wheel issue or sensor issue. Kudos to Seth at hotline again.

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Did he fax you the instructions on diagnosing sync problems? It is pretty good, it was a paper written by an engineer whom he did not name. I had to read it a couple of times before I understood it. To be honest, I would have to read it again to use it or describe it. Maybe when I get back from vacation I will dig it up and post it. Fortunately, sync concerns are not all that common. Unfortunately, they can be really hard to diagnose. All it takes is a bad connection or break in the circuit, you correct it for a while by moving things around, disconnecting, reconnecting... only to chase your tail all day. /forums/images/%%GRAEMLIN_URL%%/banghead.gif It can make you feel like an idiot!

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And then to top it all off you're pretty much replacing both cam and cranks sensors the first time, then the harness. I hate to say it but thats the only way to get those int. ones diaged. I've done that on a few and they've never came back for the same concern. All the times iver heard of a crankshaft thrust bearing causing no sync the techs have stumbled upon it on accident. I want to see one, but i think ive only heard bout that on the early 03's

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  • 2 weeks later...

Update with fix. Tech working on truck removed ckp sensor and looked in hole while turning motor and found a bent tooth. He raised engine and dropped pan down and trie to straighten the tooth (the motor had shifted in the crate while being shipped). Redrove and still no good. Called hotline and they said the slightest knick in the trigger wheel can cause issues. The only way to get the wheel is to get a crank and they said replacing the crank could cause bedplate issues. Which is why the truck is in the shop in the first place. So hotline said put another short block in it.

 

This advice was followed and truck is done and on the road. Another hard lesson to look replacement parts over really well.

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I performed the ultimate wiggle test this weekend. Had an '05 with very intermitant drop off in power (hiccup). Truck was also venting out degas bottle. Test drove numerous times with no verification for the stumble. Truck needed head gaskets so I told the guy I would go ahead and fix what I knew was wrong.

 

Replaced the head gaskets and upon test drive truck wouldn't go over half throttle, cutout horrible. Spit out code p0336 and the sync would go to no with very erratic rpm pid. While doing the head gaskets and moving the harness around all over the place I "stumbled" upon his hiccup problem. I replaced the harness and all is well.

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I could not find my copy of the document so I asked the HotLine to resend it and they did very quickly. I needed this today for a truck we have been playing tag with for a year. Finally died and stayed dead long enough to diagnose. Move the harness right at the CMP and we restored the signal. Will install a connector pigtail in the morning.

And Bruce reminded me to post this... hope you guys find this helpful. I know I did.

sync.pdf
 

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