97 7.3 Cyl Contribution Test

[ktmlew]

Does it test cyls 1-8 like the buzz test or by firing order? Have a truck with a random miss under load around 2300 rpm. The miss is apparent during the cyl cont test but doesn't kick any codes. I suspect UCH is the problem just trying to decide which side to start on.

[Brad Clayton]

I would think a buzz test would reveal some under valve cover harness issues, no?

[ktmlew]

I would think a buzz test would reveal some under valve cover harness issues, no?

Oddly enough it didn't. Ran KOER/Buzz/CCT three times each. No codes and only time it would "miss" was during the cyl cont test.

 

The CCT seems to make two passes through the cyls? I'm not sure it it does 2 tests back-to-back on each cyl or runs through 8 & repeats?

 

This truck has been dead-in-the-water for almost 1.5 years. Was a real bitch to get started. Finally had to disable the GP's and squirt it with starting fluid. Even then took a lot of cranking as the HP oiling system had been run dry due to a bad cam sensor.

 

One thing that made me wonder was the buzz test wouldn't run when it was cold? It would say testing, then after about 10 seconds, read "Pass". Never a click. Buzz test sounded perfect once it was warm.

 

My plan at this point is to remove RH valve cover first and inspect UCH.

[ktmlew]

OK. Found the test description in the PCED. It tests 1-8, and if no fault found, tests each bank individually.

 

That didn't help as it appeared to miss on cyl 4 & 5. If UCH issue I would expect paired cyls.