New Navastar CPS freaked out my PCM
 

New Navastar CPS freaked out my PCM

I had the light gray w/purple o-ring recall cps in my 7.3L. I have been experiencing a drop in performance, fuel mileage and slightly rough idle. After reading hundreds of posts about CPS problems I decided to test my CPS.

I used AE to do a contribution test and the #8 cylinder was under performing. I did not know to do a rotational velocity test before I pulled the light gray CPS. I did check misfires and there were none.

I purchased and installed the dark gray w/purple o-ring CPS Part# 1876736C91 from a Navastar dealer. To my eye the 1876736C91 is black with a hint of purple

I started the truck and the idle was extremely rough to the point of almost stalling, the OD light started to flash and I think that the idiot lights flashed but I’m not sure. This all happened very fast. Before I could cut the ignition the idle started to smooth out a little so I waited. In a few seconds the idle had smoothed out to better than it had been before the new CPS and the OD light stopped flashing.

I had the computer hooked up and the AE running so I checked for error codes with the truck still running (there were no error codes before installing the new CPS).
I had several new error codes:
P1705 Transmission Range Sensor out of Self-Test Range,
P1116 Engine Coolant Temperature Sensor is out of Self-Test Range,
B1203 passenger active head restraint or fuel sender circuit short to battery.

I cleared all the codes turned off the truck and restarted it and rechecked the DTCs. Only B1203 persisted.
I did another contribution test and #8 failed. P0284 Cylinder 8 Contribution Balance Fault Diagnostic.

I did a road test and the engine seemed to run slightly better than it did with the old CPS.
I did not get the vast improvement many people have claimed.

I ran a perdels (cylinder rotational velocity) test and got:
#1, 0.0
#2, 0.0-0.4 but it did flash 6.2 once about midway through the test
#3, 1.4-2.4
#4, 0.7-1.7
#5, 0.0
#6, 0.0
#7, 0.0
#8, 4.9-6.40 mostly in the mid 5’s

So I think that the new Navastar CPS is bad. What do you think? Has anyone ever had the PCM freak out like this when they put in a new CPS?
Mars
P.S. I used to be a color matcher and researcher in a company that made color concentrates for plastics and my color vision is excellent. To my eye the 1876736C91 is black with a hint of purple. If you have a weakness in your red green color vision the part would seem to have a bluish cast. Another thing to consider is that the quality control for the color in this part would not be very high and there is probably a lot a variation between production runs. I have read many posts that refer to this part# and it has been described as being black, dark charcoal, dark blue, dark gray, and even purple. Most people seem to be able to see the purple o-ring although I have read post that refer to the o-ring as blue.

Don't worry about it.

IT'S NORMAL.

Don't go chasing your tail needlessly.

http://powerstrokenation.com/forums/...milies/doh.gif

I am still working on the problem. I have been unable to get the PCM to freak out again in spite of changing the cps several times.

Currently I am trying different cps units and shimming them to different lengths in a trial and error attempt to find the correct length necessary to achieve the .025-.030 inch clearance. (I do not have the special tool). Right now I am waiting for a black cps to be delivered.

Right now I have a second dark gray w/purple o-ring cps installed and shimmed with a .010 shim. The truck seems to run pretty well but the #8 cylinder contribution is off.

I am videoing the process and I will post it when I am finished.
Mars