I installed my new CPS this evening to fix my trailer brake gremlin (hopefully...I'll test it on Sunday). My question is if my CPS was indeed getting old/going bad what were any of the ill effects it had on my engine or performance. I ask because the truck seems to be quiter and run smoother at idle and low RPM's. I could be crazy, but it sure sounds like a different truck now, whereas before it seemed louder and rougher....almost like it was working harder than it is now. Does this make any sense

 

Well, think about it. The CPS has to keep track and tell the PCM where each cylinder is in it's power stroke. If the CPS was not reporting correctly then I would think the PCM would not allow the injectors to fire, or possibly an entire bank to fire. Of course this happens so fast we simple humans see that as a rough idle. As a software programmer I'm sure there is some fudge factor built in to the software that allows this without setting the CEL.

You did bring up an interesting thought though .. where did you get the CPS and part # please.

 

Oh wow....I don't remember off hand. I'm at work now and will have to look that up later this weekend. I do know the CPS is black, or dark grey - not blue as I have seen some threads about. I bought it off ebay for ~$20 with shipping.

Here is the old link to the ebay item when I bought it: eBay Motors: NEW FORD POWERSTROKE 7.3 CAM SENSOR CPS 94-96 (item 160239929257 end time May-22-08 07:49:03 PDT)

 

This is your cam gear the camshaft position sensor is reading. The lands between the spaces on the gear are the target spokes. Each time one of those spokes passes the CPS it generates a signal that is sent to the PCM. The little spoke represents the #1 cylinder and the wide spoke 180° out is #4 (fires 5th).

Your base injection timing and your RPM signal are generated by the cam sensor....so you can see why it is important to have a properly operating sensor in the hole, and how a faulty one could adversely affect your engine.

 

The e-bay photo hides the part#.
As per dieselmans. CPS changes.

Cam Position (CMP) sensor.
The CMP sensor provides the PCM with cylinder ID and engine RPM. Sometimes hard to detect, even with a scan tool while monitoring the RPM signal. If the PCM does not receive a clear CMP signal, it won't signal the Injector Driver Module (IDM) to energize the injector solenoids.
If this symptom occurs, or if you find one or more of the above codes, check the wiring to the CMP for continuity--BOB pin 90 to CMP pin B; BOB pin 65 to CMP pin A; BOB pin 49 to CMP pin C. NOTE: A code P0344 may be set any time the engine is cranked for an excessive period of time. Early CMP sensors were @ 1.152" in length, and with the different materials--plastic sensor, aluminum timing cover, steel tone ring) the air gap would change drastically during engine warm-up. There were TSB's published for shimming the sensors 0.010" to cure these problems as well as the drastic repair of replacing the camshaft--something a Navistar tech assist rep recommended not doing even if excessive end play was verified. There have been two updates to the CMP. One to decrease the length to 1.142", and also to improve the internal circuitry for less "noise". The CMP designed for engines built after serial number 375549 have gold-plated terminals and cannot be substituted with those designed for previous engines.
94-96 CMP: F6TZ-12K073-A; original Navistar part suffix C-96, C-97; replaced by C-98; replaced by C-99
97 CMP: F7TZ-12K073-A; early suffix C-91; replaced by late suffex C-92; both replaced by C-93.
The suffex is stamped on the connector end of the CMP and can be used to identify the level of the part installed. Replace any CMP's with a suffex of C-96, 97, 91 if these symptoms are experienced. Lube the o-ring and connector with silicone dielectric grease when installing.

And now we have the AB CPS and is grey in color.

Bill

 

Very interesting....amazing how a little plastic "****" looking thing can be so important to the health of the engine

Looks nothing like the front of any engines I've ever seen

Oh, and the new CPS I installed did appear to be a tad shorter than the old one.

Truck is running great, and it seemed to run fine before it just seems to be noticeably quieter and smoother. I guess its time to buy another CPS of the same type as a backup for down the road someday since these things apparently are known to go bad w/o warning.

 

Scott, thanks for the photo on the cam gear. That clears up a lot in my mind how this thing really works. At work we use CPS's (hall effect devices) to control RPM on motors. And boy is the adjustment critical, I'm talking +- 1/2 mm will cause that motor to hunt for proper speed. I'm simply amazed how well this works in the Power Stroke engines, well most of the time anyway.

 

this is the part number the seller gave me last week for that auction
f4tz12k073c

 

so is this 'black' sensor better for our trucks?? and seeing as how it works in the 96's it should work in my 97 correct?

 

Some trucks run the new gray sensor just fine. Some don't. mine hates the new gray sensor

 

changed mined the other day, with the gray one and it seems to have made the engine idle smoother, or maybe it's just me