Camshaft position fault

Jason Mechanic Brooklyn, New York Posted   Latest  
Case Study
Heavy Duty
2003 International 4300 7.6L (DT466)
Fault Code 143 Sid 21 Fmi 2
When Hot Smoke And Misfire On Acceleration

Truck came to the shop with the complaint that when hot heavy smoke from exhaust. I scanned the vehicle and found multiple codes stored in the ecm: ambient air temp: PID 171 FMI 3, engine position sensor: SID 21 FMI 2, injection control pressure: PID 164 FMI 0, controller #1: PID 100 FMI 1, boost pressure: PID 102 FMI 4. I decided to drive the vehicle and verify the complaint, at first the truck ran fine no problems no smoke no warning lights after about a half hour of driving with engine at operating temp it started acting up. I found during acceleration there was heavy smoke and the truck felt like it was misfiring or shuddering let go of the pedal it would idle good with no smoke or shakiness. I pulled over rescanned for trouble codes and found engine position sensor code current no other active codes. When I got back to the shop I decided to scope the sensor and see what’s happening when it was acting up, figuring it was a bad sensor but wanting to confirm it. I found a lot of noise in the circuits for the CMP sensor, which lead me down a rabbit hole for awhile finding out what was causing this noise(injectors) and testing powers and grounds at the ecm thinking this noise was my problem. After researching service information and re analyzing the waveforms I had captured I found that when increasing engine rpm the sensor would fail to read the narrow vane window(cyl 1) on the camshaft timing disk causing the ecm to miscalculate injection timing firing the injectors at the incorrect time in relation to piston positions. Included is some scope captures before and after replacing the camshaft position sensor. Blue: 5v ref, Green: sensor ground, Yellow: signal Red: injector current for 1,2,3 firing order is 1/5/3/6/2/4. I still do not like the noise in the circuits but the truck was happy with a new sensor and did not act up again after an extended test drive. I am still new to the heavy duty side, still learning, and first time posting on diag I would like to hear any feed back especially on why there was so much noise from the injectors firing in the circuits of the ecm including the powers and grounds of the ecm.

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Zachary Mobile Technician
Austin, Texas
Zachary
 

This is just a general thought about noise on a circuit but did you happen to check AC ripple voltage? That's become one of my standard checks on a vehicle whenever there's circuit noise that's concerning. Or for that matter any weird electrical thing that doesn't seem to have a clear cause. Just in case you're unfamiliar, the way I was taught is to check it directly at the bat post of the…

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Jason Mechanic
Brooklyn, New York
Jason
 

Thanks for the input and will keep it in mind for future vehicles but no i did not check ac ripple at the alternator but did think of it as a cause. When I first looked at the scope capture I focused on the noise, which was a mistake, and noticed the noise had a sequence to it and almost looked like current ramps which made me think what kind of ecm controlled actuators could be causing this and…

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Zachary Mobile Technician
Austin, Texas
Zachary
 

I hear ya brother. You always wonder if things like that are relevant or not. I'm not familiar enough with that engine to say for sure but I've worked on a number of the T444E engines in Powerstroke form in the Fords. They have some issues for sure with cam sensors so perhaps it's something about Internationals of this vintage. I've definitely had aftermarket sensors do weird things on the 7.3s…

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Jason Mechanic
Brooklyn, New York
Jason
 

Not that I saw in the wiring diagram internal to the ecm maybe not sure tho

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Rex Technical Support Specialist
Alliance, Ohio
Rex
 

Condensed version. That 3 wire CMP sensor caused a lot of problems. About half wo codes. To save dollars get the the Ford CMP for the 7.3 IDIT aka T444E. Very cheap, $25.00, will move timing 2 degrees on the DT which is an improvement. Cam thrust plate will also wear moving disc away from sensor. It will hiccup under load and usually code. Correct fix is take front cover off to replace cam…

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Gary Owner/Technician
Owings, Maryland
Gary
 

Hi Jason, We ran into this a few times on various DT466E engines. On some of these higher mileage units, the cam thrust bearings wear, and the cam "walks" back under load at higher RPMs, (causing your air gap problem) usually whilst pulling through 2nd and 3rd gear, but would be fine at idle and lower RPMs and loads. After MANY hours of scoping and trying to figure out why the new sensor from…

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