Intermittent starting issue

[Dm85]

Hello, it has 1 year passed. Did you resolve your problem? I have almost same one. Only occour when night temperature fall below 5C degrees. I have replaced lifting pump in tank. and made plenty of measurments. Pressure 30 000kpa in rail is build after 4-5 sec of cranking. In rail the pressure stay at 0-300kpa level so no injectiors leaking. Only missing fuel in HPFP supply line. Only after cold night... All other situations car work smooth. Any new idea?

Could it be a faulty glow plug? I know we rely on codes but sometimes they don’t throw one.

 

[jackthesoul]

Could it be a faulty glow plug? I know we rely on codes but sometimes they don’t throw one.

Just got some news to check them as next, but todays weather is pretty hot and car always start smoth.
Faulty glow plug would not make fuel presure rise so slow. Find two sample of measurment below (left column - timestamp, right - railpressure in Kpa). Yellow marker starting crank, green - idle RPM (car start).

 

[Dm85]

Just got some news to check them as next, but todays weather is pretty hot and car always start smoth.
Faulty glow plug would not make fuel presure rise so slow. Find two sample of measurment below (left column - timestamp, right - railpressure in Kpa). Yellow marker starting crank, green - idle RPM (car start).

View attachment 240322

Seems like the rail pressure is ok when idling.

I get around 31,000/32,000 kpa. What should fuel rail pressure be in the morning before starting? Mine holds a few hundred kpa when warm but should that be the case when left over night?

I’m almost adamant I have an either a faulty injector or the is slightly off. Anyhow going to get some diagnostics and testing done soon so I’ll let you know what the out come is.

Tempted to do a leak off test on the injectors but it’s a PITA taking the charge cooler off and on 2 times

I’ve had the van since new so I know something is amiss. I’ll get to the bottom of it hopefully. One thing that is a bit concerning is I can see a wobble on crank pulley. And the cam sprocket. Also a rippling type noise…. I removed the aux belt and it was still there so that has got me questioning the timing section. VW changed it less than 2 years ago tho, but that doesn’t mean something hasn’t slipped or a bearing issue possibly. Cam phase adjustment seems to vary but averages 4.5 degrees positive. No fault codes but seems a bit high on the cam phase for only 18 months?

View attachment 240321

 

[mickygee]

I am having the same non start intermitent issue also. However the temp here is not cold so that wouldn't be a factor. I'm also totally a newby with these cars and don't have any reading tools.
Is there any direction I can be looking at for a solution?
Car is highline 4 motion i450

 

[PearShaped]

I am having the same non start intermitent issue also. However the temp here is not cold so that wouldn't be a factor. I'm also totally a newby with these cars and don't have any reading tools.
Is there any direction I can be looking at for a solution?
Car is highline 4 motion i450

Any update on this?

 

[mickygee]

It's only been a couple weeks, but I had the MAF sensor cleaned and I haven't had the problem since. I normally would have experienced the non start a few times by now. I will report back if the problem happens again