Ever since I bought the OBS after driving for a while if you come to a stop it runs a little rough... can't really see the motor moving if you are looking under the hood but you can feel a bit of vibration in the cab. Last night when I got home it was doing this, so I pulled out the AE. While AE was trying to connect it died on me. I got it restarted but it was kind of cranky to re-start, almost died one more time (WTS light came on but it stayed running). Ran KOER, cylinder contribution and everything was fine. Shut it down and ran KOEO and I get 2 codes (I believe P1272 an P1274), #2 and #4 hi to low side open.
Just for ****s and giggles I swapped the gray CPS with a used black spare I have and I checked all the UVCH connections on the outside- no burned connectors or loose wires. Ran the KOEO again and got the same 2 codes. Truck is running fine, doesn't hiccup or cough at all while driving. I'm hoping to pop the valve covers off this weekend and see how the UVCH's look inside, any other suggestions?

 

Sorry, can't really help ya. I had a problem where when I would come to a stop the engine would kinda bog down and idle rough for a second, but then idle normal. Did that slowing down for tight turns also.
Not sure why it did it, but it's fine now.

When you gonna update your Avatar pic and garage pics?

 

Chase, you may want to clean the FRP return screen too ...

 

Yeah I need to search up on that. Oil/filter change is coming up soon, I figure at that time I will change the fuel filter, clean the FPR, maybe shim it if it needs it, and I'd really like to change the coolant, front/rear diff fluid, and PS fluid at the same time.

 

Whenever I remember to do it

 

I ohmed out all the connections yesterday, here's what I found:

Cylinder Injector GP
1 3.0 0.08
2 3.8 1.4
3 2.9 Open
4 3.5 Open
5 3.0 1.1
6 3.0 Open
7 3.1 Open
8 3.0 Open

Today I popped the valve covers off just to see how things looked, I didn't see any loose connections or burned wiring anywhere. Just to see what would happen I swapped the front and rear UVCH on the driver's side to see if the codes would follow the harness or stay with #2 and #4, still getting P1272 and P1274, #2 and #4 Hi to Low side open So now what- engine harness? IDM? Bad solenoids?

 

I would think if you had two cylinders out it would run like crap.
Does it run the same with those injectors unplugged?
Did you clear the codes before retesting, old codes?

 

Hopefully you just swapped the connectors and did a buzz test. Don't start the engine with the pluggs crossed. If you swapped the front and back connector and still got the same codes, then your problem is with the wiring. Remember the PCM doesn't know you switch connectors so it thinks the wires you now have going to 6 & 8 are still connected to 2 & 4. If you had a soleniod / injector issue, it would trip 6 & 8 codes with the wires swapped.

 

CCT is finicky.

I'ma bet you have something simple like a broke spring in the nozzle.
It made mine idle funny like that, but all of mine were broke.
With new injectors, my truck still rocks after idling for a minute or 2.

 

Jim I will try unplugging #2 and #4 in the AM and see if it makes a difference.
Chris- I didn't swap the external connectors, I swapped the UVCH harnesses under the valve covers on the driver's side. Remember there are 2 per side on an OBS. So I took the harness for #6 and #8 and moved it to #2 and #4 and vice versa.
Talyn this truck only has 147k miles on it so I doubt there is any significant wear in the injectors. It has zero blowby and was clean as a whistle under the covers. The rough idle could be IPR or fuel pressure related, hard to say at this point.

 

You may want to check the poppet screws also ...

 

140k miles, and how much of its on ULSD, and how hard was it ran.

ULSD kills our injectors without any passion.

 

I ran all the KOEO/KOER tests again last night and the P1272/P1274 codes didn't come back. I got a few random codes for misc. crap that doesn't concern me in the slightest, so I guess all is well.

 

Good to hear. Hope it's all ok.