Intermittent Start Up Fault - Resolved!

[Del94]

So, I’m just on my way back to the service centre to collect my van again!

Start up fault

Hi again, I'm trying to record my van when in fault with my new VCDS. I think the attached might show the fault? The problem is the fault doesn't present every start up. Once when I was trying to record it the VCDS just displayed n/a in every column. I've ticked the boxes that delmassive...

www.t6forum.com

After the centre replaced the crank sensor ( third visit, first visit fuel pressure sensor - second timing belt and tensioner ) the problem worsened dramatically.
The van went back in on Friday and thankfully the technician managed to get the the computer on it and they witnessed the fault live for the first time.
Turns out they’ve found the fuel pump relay has a “dodgy pin” and was fitted that way when the van was built, hence the intermittent nature of the fault.
I’ve persevered with this since it was a couple of months old because apart from this tiresome gremlin I absolutely love it.
So hopefully this time it’s fixed

 

[Broadside]

Fingers crossed for you , I do hope they’ve fixed it.

 

[Del94]

So, I’m just on my way back to the service centre to collect my van again!

Start up fault

Hi again, I'm trying to record my van when in fault with my new VCDS. I think the attached might show the fault? The problem is the fault doesn't present every start up. Once when I was trying to record it the VCDS just displayed n/a in every column. I've ticked the boxes that delmassive...

www.t6forum.com

After the centre replaced the crank sensor ( third visit, first visit fuel pressure sensor - second timing belt and tensioner ) the problem worsened dramatically.
The van went back in on Friday and thankfully the technician managed to get the the computer on it and they witnessed the fault live for the first time.
Turns out they’ve found the fuel pump relay has a “dodgy pin” and was fitted that way when the van was built, hence the intermittent nature of the fault.
I’ve persevered with this since it was a couple of months old because apart from this tiresome gremlin I absolutely love it.
So hopefully this time it’s fixed

Nearly two weeks and the fault has not reoccurred, I’m hopeful it’s fixed

 

[Jeff@tuneserv]

In my case the fault only occurs if the car above 60 deg . So if I clear the fault and start from cold there is no fault . Above 60 deg and stood for 5 min the fault is there every time . I can clear the fault and drive all day and no fault . Switch off wait and it there straight back again.

So frustrating. Autel 909 says DPF OK and not due for regen . Will try a forced regen today .

 

[Jeff@tuneserv]

Problem solved ! On further investigation and while working the check engine light went out by itself and never came on again. So I decided to check the pins on the ecu and check for corrosion. While checking I found that this vehicle had had a Unichip fitted at some stage. Maybe because the guy has added every conceivable accessory and vehicle just to heavy The Unichip is connected into the main engine harness. It requires ...Power ,earth,tps,fuel in. ie.rail pressure and crank shaft signal. There appears to be a bad connection on the rail pressure wire . With the unichip removed and the wires returned to standard . The problem has gone. I also noticed black smoke on acceleration meaning Unichip fueling values in the map were excessive. The EGTS would have been to high , so good thing it is out .

So always look for aftermarket components as a first stop before going any deeper.

 

[roadtripper]

Good find. I have a healthy skepticism about remapping at the best of times but while it's one thing to tweak the ECU it's a wholly different thing to add electronics that try to bypass the ECU or send it synthetic data.