PO340 Diagnosis help

[freshspecbluegt]

Hi all,

I have been chasing an intermittent stumble and occasional stall for some time now. neither the stumble nor the stall trigger a CEL, and the truck will start right back up and run like normal. Occurs exclusively at just off idle, when starting off from a light or stop sign. I have worked through lots of different diagnoses and replaced a number of parts:

Harness is in good shape, no burns, rewrapped zip-tied away from EGR
Replaced fuel pump with new sock
New TPS
IAC passes resistance tests
FPR replaced
EFI relay replaced
Open circuit relay replaced

Finally had a more significant stumble and multiple stalls and threw a PO340 Camshaft code.

First test:

Results:

(-)	(+)	Ώ	Result
4	3	234Ω	Pass
4	2	9 MΩ	Fail
3	2	9 MΩ	Fail

So Looks like I need a new distributor ( too bad housing alone is NLA now).

What I am trying to wrap my head around is why if this failed am I only getting an intermittent issue?
Did I run this test correctly based on the description?
Any idea why this wouldn't be throwing a code constantly if this failed? ( cleared code and it has not come back in 150 miles, a couple of stumble events have occured though.)

Will go ahead and replace distributor but trying to understand if I am really getting to the bottom of the issue or not.

Appreciate any input.

 

[Fj80oregon]

Did you test continuity for the wiring harness I know this a huge pain but visually looking at wires will not tell you if there is a break somewhere else in the harness. Look in the parting out section to find a used distributor. @swamp-thing or @slow95z should have one if they don’t I prob have one in the bins.

 

[swamp-thing]

I definitely have a distributor here, message me if you want to snag one — thanks for the shout out @Fj80oregon

 

[freshspecbluegt]

Circling back to the close the loop on this one. Big Shout out to @swamp-thing for working with me on testing. He provided a good used distributor and problems have been resolved. About 1K miles post install and no issues. The hesitation and stalling was intermittent and was getting worse. First time a CEL was triggered was the PO340 reported above.

I would add the PO340 test if you are struggling with hesitation and stalling and the rest of the normal checks are not providing a resolution. I had these issues for about a year before the CEL triggered.