CP3 Slipping when it is cold?

[g_dog1]

Hi Guys. For about 3yrs now, when the temperature reaches around the freezing point, my truck acts up. In the summer time, it is flawless.
In the winter seasons while driving, it will experience intermittent power surges. Doesn't happen all the time, and might only happen once in a 30mile trip. The worst part is that there is no check engine light or code. Without a check engine light, I don't know where to start diagnosing. It feels like the transmission would slip, then harshly grab again, or it would lose power, then gain it back again. This is sometime accompanied by a horrible knocking sound (like in a gas engine).
Removed Smarty Jr. - no difference
Changed fuel filters - no difference
disconnected grid heater relay - no difference
Changed FCA - No difference
Changed injectors - no difference
Changed transmission and torque converter - no difference
Had the ECM reflashed - no difference.
Changed Crank position sensor - no difference.
Installed a fuel pressure gauge to read pressure at the CP3 inlet - pressure is usually 5 to 8 PSI. It doesn't fluctuate much, and is probably really slow to react to any change.
Installed a fuel rail pressure gauge. During the power surging, I think the rail pressure drops, then comes back again.
Is it possible that the CP3 might slip that grab again causing me to lose pressure, then get it all back again?

Thanks guys.
Your input is valued.

 

[jgillott]

I had a similar issue several years ago where I would get an intermittent surge as you described on my '07. It would also show a quick drop in rail pressure when it would happen. I chased that problem for months.

Anyway, making a long story short, the problem turned out to be the connector on the wiring harness going to the rail pressure sensor. If I would take it apart, clean it, and reinstall it with dielectric grease, it would work great for awhile. Eventually, I had to replace the harness. No problems since.

 

[TCDiesel]

1st guess Post #2 ,2nd guest I would try replacing the MAP Sensor, its extremely doubtful the CP3 is the problem. 3rd Guess TIPM connections. 4th guess check all connections and use dielectric grease.

 

[g_dog1]

I had a similar issue several years ago where I would get an intermittent surge as you described on my '07. It would also show a quick drop in rail pressure when it would happen. I chased that problem for months.

Anyway, making a long story short, the problem turned out to be the connector on the wiring harness going to the rail pressure sensor. If I would take it apart, clean it, and reinstall it with dielectric grease, it would work great for awhile. Eventually, I had to replace the harness. No problems since.

JGillott - I take it that you didn't get any check engine lights? How much of the harness had to be replaced and wht did that cost?

 

[g_dog1]

1st guess Post #2 ,2nd guest I would try replacing the MAP Sensor, its extremely doubtful the CP3 is the problem. 3rd Guess TIPM connections. 4th guess check all connections and use dielectric grease.

Good to hear from you TC. I checked all the TIPM connections, and looked for something loose to no avail. How about a bad ECM?

 

[TCDiesel]

Not likely.......The TIPM may need resetting/updating that procedure is very complex, BC it requires programing the VIN into the ECM,BCM, PCM ,TIPM, and programing the SKIM if you have the big KEY. I tried to walk one tech threw it , when ALL said and done the truck was flatbed to here and I did it. Have you double triple checked ALL the battery connections, I'm still thinking its electrical. check all the ground connections everything.

 

[jgillott]

JGillott - I take it that you didn't get any check engine lights? How much of the harness had to be replaced and wht did that cost?

It was just the connector end of the factory harness. Sorry, I wasn't very clear in my first reply. PM sent.

 

[g_dog1]

Thanks for the responses guys. I have looked over all the wires and grounds and haven't found the issue yet. I agree that the issue is electrical, but with no code, and not being able to reproduce the issue for a scan tool, I am just guessing at every effort I make. If it was a grounding issue or loose wire, I would think that it would happen in the summer time also, or when driving over bumpy roads. It only intermittently happens in the winter time, and the effect are much worse when I am on the throttle a bit harder. Ex: accelerating, or climbing a hill. Sometimes the truck will even throw me in my seat, or just "miss" or stumble (like the timing is bad)....then the issue is gone. It will react much harsher than I could ever try to produce by playing with the accelerator pedal. Ironically enough, I have never noticed the issue while just idling. Only notice it when the demand for fuel is on.

I'll replace the MAP, and the MAF sensor and see what happens. I'll try wiggling all the connections with the truck running. I would also like to go to a dealer and swap ECM and TIPM for a week, to see if that resolves the issue. I really need a scanner that will record data after the event occurs, so I can see what signals are acting up.

Thanks for the help guys.