After reading all the issues that seem to come from the Gray CPS on some trucks, I've been monitoring my truck with the AE scanner. I've had the gray CPS for about 45,000 miles and have had NO noticeable issues with my truck. According to AE, the rotational velocity has been high on cylinders #3 & #8, and they would fail the cylinder contribution test, but again, no noticeable issues from sitting in the drivers seat.

I ordered a black IH CPS from DP-Tuner and stuck it in, taking readings on AE before and after. Both numbers came with EOT above 170 deg.

Rotational Velocity %

Cylinder 1 Gray 0.2 Black 0.2
Cylinder 2 Gray 1.1 Black 1.3
Cylinder 3 Gray 1.9 Black 0.1
Cylinder 4 Gray 0.4 Black 0.6
Cylinder 5 Gray 0 Black 0
Cylinder 6 Gray 0 Black 0
Cylinder 7 Gray 0 Black 0
Cylinder 8 Gray 2.8 - 3.5 Black 0.4

The gray CPS failed #3 & #8 on the CCT. The black one passed all cylinders. I'll see if I notice any SOTP feel after I get a few miles on it.

This info may vary with different trucks, but I thought I would pass on my findings.

 

well chris sounds like thats what i need to be doin ha ha

whats SOTP by the way

 

That's one of those fancy tools some folks use to gauge performance.

It's called the Seat Of The Pants meter aka butt dyno.

 

sorry atleast now i know

 

Great job on the test Chris. This has also been on my mind since alot of people been asking about the difference Between black and gray. I,m wondering, with the failing of the #3 and#8 cylinder, could that also contribute to the loud no#8 we sometimes hear?? Tried to rep yaa, spread around issue..

 

Chris,

That is pretty conclusive. Thanks for the side-by-side numbers.

 

i dont think it would cause 3 and 8 to fail but im not sure...

 

Nice job Chris, I also tried to rep you but cant

 

I don't think so since the noisy #8 has been around a lot longer than the gray CPS. I also never noticed (nor has anyone else complained about) more noise when switching over to the gray one.

He meant failing the cylinder contribution test, which mine did.

 

This explains my CCT results from last week. All 8 of my cylinders passed the test before I put the gray CPS in (about 1 year ago). I haven't used my AE since but I hooked it up last week for fun and #3 and #8 both failed the CCT and the rotational decel numbers on these cylinders were high. I never considered that it might be the CPS. I still have the original black one in the glove box. It was somewhat intermitant before i changged it but I will put it in this week and see if I get similar results

Edit====> I also noticed that the rotationnal deceleration number all dropped to 0 when I increased the engine speed above idle

 

That's normal. The scanner can only take the readings at idle.

I got a chance to put 200 miles on the truck today, making several stops along the way. As I stated earlier, there was nothing wrong with the way my truck ran or idled with the gray one, but it does seem smoother with the black one.

Besides just the general sound/feel, the best indication I could find of a smoother idle was lightly touching the stick shift at idle. The vibration of the stick in neutral (with a light touch) is much smoother with the black one. With the gray one you could just feel a slight miss in the stick.

I know Mueckster has made this observation about the black CPS being smoother already. I guess this serves as a second opinion, and agreement with his findings.

If you're running the gray CPS, you might consider picking up a black one from Jody & Diane.

 

Great Post Chris . You're the MAN!

 

Im sold im putting the black one back in soon. Ill rep ya if i can.thx

 

Chris, your results are right in line with a few other's who have run the same exact test.

 

Thanks for the conclusive data. I felt a difference, but thought it was in head. The bad part is, I gave my brand new black one to my next door neighbor when he was in need and I got a grey in return. I need to order a bunch of misc. maintenance items anyways... one more just added to the list.

Thanks again, reps coming your way

Austin