pd stutter and stall

[akafred]

2005 jetta tdi

it stalls randomly, no codes stored, scanned with vcds

lift pump was dead, replaced it

tandem pump was still pumping a significant amount of return fuel even with the dead lift pump so i assume its fine.

what should i do to trouble shoot this random stall issue?

swapped 109 relay, no difference

i also noticed that when it stalls vcds disconnects from ecm. this led me to think the 109 may be bad.

 

[lbirunner]

Have you considered your crank position sensor? Search CPS with my username and you should find more info..

 

[akafred]

Was actually considering that, i did have one go bad in a alh car, it would just crank and crank.

Problem is that its moms car, they are close to retirement and cheap/broke as f... dont want to throw parts at it.

Also weird that vcds cuts out when it stalls, should it not stay connected if its engine speed sensor "CPS"

 

[gatz]

Sounds like an electrical issue if you're losing the ECM. Grounds would be worth checking & cleaning, along with the battery connections. You might need an oscilloscope to really get anywhere with electrical problems if guessing doesn't solve it.

 

[lbirunner]

If it's the CPS you can check it by wiggling the CPS wire bundle while the car is idling. The issue is the insulation on the wires inside the bundle deteriorates. The engine will stall if that is the case.

 

[akafred]

this solved the issue, was the CPS, jiggled the wires and car died instant, did it a couple times in a row to make sure.

If it's the CPS you can check it by wiggling the CPS wire bundle while the car is idling. The issue is the insulation on the wires inside the bundle deteriorates. The engine will stall if that is the case.

 

[where2]

Yeah, when I diagnosed my CPS at fault for a similar no-start on my BEW, I removed it and slit the outer jacket of the CPS wiring on the kitchen counter. I figured I'd be able to splice the offending segment of wire, NOPE! The insulation on the three wires inside was so crumbly I could not possibly splice it to even temporarily fix the problem.