Anyone got any ideas what could be wrong with my stupid car?

[mrmen]

Any help with ideas of things to look into before I torch it and buy something else

Audi A3 2.0 TDI 2005 BKD

About once a week my car will not start it turns over but won't fire up, I let it sit for a day or two and then try again and it will start up. This problem is starting to get pretty annoying as its made me late for work a few to many times now.

I've checked the fuel is going past the filter, checked the ECU grounding straps, checked cranking speed which looks good but don't know what speed .its actually supposed to be? I hooked it up to VCDS Lite but no fault codes present.

When it does eventually start up it runs pretty rough producing a few clouds out the back but a 5 min drive around the houses sorts it out, the rest of the time it runs fine no problems at all. Its been to a good indy garage but as the starting issue didn't happen when it was there they found no faults.

Has anyone had a similar issue, know something I should check or look for on VCDS?

Thanks for any help.

 

[Gm95]

I'm no mechanic and I do not claim to know much about diesels at all but you seem to have checked a lot of the advanced stuff. Have you thought about something smaller like the glow plugs or whatever powers the plugs at all?

I know you'd expect it to show a light and log a fault code but in my mind the symptoms seem likely? (Cylinder is sometimes not getting warm enough to ignite and when it does, smoke clouds out the back meaning un-burnt diesel?)

 

[Retroman]

I would guess at glow plugs. If it was fuel supply it would not necessarily improve on a warmed up engine and something like a coolant or MAF sensor would throw an error code.

 

[mrmen]

I did replace all the glow plugs about a year and a half ago so was thinking they should be ok but I'll give them a test to make sure

 

[nluk100]

Does it show as cranking on vcds when it doesn't start as it could be an intermittant crank sensor?

 

[mrmen]

On VCDS when reading the measuring blocks group 1 it does come up with a rpm when cranking which I think comes from crank sensor but I maybe wrong?

 

[Omy193]

A very common issue on the a3 2.0l tdi's out of experience is the injector wiring, it becomes brittle over time.
But of course it could be something completely different on your car