Cam Position Sensor Information

I have been intrigued by the everlasting Cam Position Sensor issues since replacing one on a friend’s truck in a parking lot, due to a no start situation after driving fine only minutes before.

When I bought by ’02 the first thing I did was order a spare CPS and throw it in the glove box like so many other 7.3 owners. Over the years I have read many posts and looked at the data the posters provided to make conclusions. Well the other day I decided to order one of the new Dark Blue CPS to see if it would make a difference.

I have noticed a slight miss in the idle of my truck since the dealer put in the grey “recall” CPS. I can’t complain too much, since it seems to run fine everywhere else and my wife will tell you there is nothing wrong at idle, even if I “show” her the feeling of the miss that I feel. I have pondered throwing in the spare Black CPS, but I have also read where some guys are getting less MPG on the black one versus the Grey one.

So when my new Dark Blue CPS arrived in the mail from Tousley Ford (great deal by the way and fast shipping) I decided to break out the AutoEnginuity for some testing of Perdels and Cylinder Contribution Tests (CCT). I decided to run everything in the stock setting on my DP-Tuner to keep it as close to real as possible. Truck was warmed up to get the Engine Oil Temp to spec where Perdels could be read.

CPS Information:

Black CPS P/N: F7TZ-12K073-A

Grey CPS P/N: F7TZ-12K073-B

Dark Blue CPS P/N: F4TZ-12K073-C

Cam Position Sensor Shimming Instructions

Black CPS is marked as: 1825899

Grey CPS is marked as: 1876735C91

Dark Blue CPS is marked as: 1876736C91

One thing I did notice about the three different sensors is the body that goes inside the block is much larger on the original Black CPS compared to the two newer versions. Does this have something to do with why they read differently? The Black one has a diameter of 0.892” while the Grey and Dark Blue have a diameter of 0.720”. Maybe nothing since it is just a plastic case, but it did make me think it could have something to do with it.

Here is the data from the Perdels tests:

The Black CPS brought Cylinder 3 and 8 down to a respectable level. Idle was very smooth and CCT passed with no codes. Start took less time than normal although the engine was warmed up.

The Grey CPS performed the same as I have seen in other posts. Cylinder 3 was higher than most and Cylinder 8 was above the 5% limit which appears to make the CCT fail. The CCT test did fail and gave me P0284 Cylinder 8 Injector Circuit Contribution / Balance Fault. Idle seemed to be smooth but if I pay close attention and lean on the door sill, I can feel the slight miss. Appeared to crank a second or two longer than the Black CPS, but nothing unusual and engine was warmed up

The Dark Blue CPS surprised me! The Perdels for Cylinder # 3 were much higher than the Black CPS and even higher than the Grey CPS. Cylinder #8 was slightly less than the Grey CPS reading. The CCT test failed on Cylinder #3 & #8 with codes P0269 & P0284. Appeared to crank a second or two longer than the Black CPS, but nothing unusual and engine was warmed up.

I was a little confused why the Dark Blue CPS (which is claimed to be the “new better version”) did a little better on cylinder #8 but far worse on Cylinder #3. The truck has a much more noticeable miss at idle now too. I will leave it in for a few weeks to see if it performs any differently or has any noticeable effect of fuel mileage.

I guess I would be curious to have a batch of CPS, and then I could run each one to see if it is a manufacturing issue or a design issue. I imagine I will end up pulling out the Dark Blue CPS and install the Black CPS. If I see my mileage drop way down I will probably drop in the Grey CPS again as it idles much more smoothly.

I'm sure every truck will perform a little differently, but this is what I came up with. I did pull various other data during these tests but limited the Perdels and CCT tests as the purpose of this post.

UPDATE:

I did tear apart a CPS to see why it was not working on a truck. I posted the pictures on FTE. CPS Teardown

Phantom CPS Codes on a CCT? Here is a little tidbit from Ford to their service teams.