Hi, I am new to the forum and looking for some advice. I was given an Audi A3 2007 16v by a friend. The car had snapped the cam belt tensioner on the motorway. We recovered the car and tried a new belt on it as we could feel 4 compression's. Belt fitted and it started up, running rough and blue smoke from the exhaust,but running. It would rev up, we kept the revs low and attempted to slowly drive it around the block to see if the smoke would clear. It ran maybe 2 miles and came to a stuttering stop. the symptoms best described as low voltage to ECU, flat battery or running out of fuel. On trying to start it,it would run for 2 or 3 seconds and stop. Since then we have removed cyl head where we found broken rockers. Cyl head has been rebuilt with new valves,rockers, skimmed and refitted to the engine. Since refitting it has the same symptoms, will start for a few seconds and stop, sometimes doesnt fire but when it does runs and stops. We are thinking its a fuel problem, fuel is being pumped to the high pressure pump but from there the fuel goes into the gallery of the cyl head. There is no fault codes showing other than a B3 fault that we will investigate but doesnt seem to be connected to our fault.
I would appreciate any help you knowledgeable people may have as we are running out of ideas. Thanks in advance

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Raymond.

If the rockers were broken it was because the valves hit the crowns of the pistons, so they are likely to also be damaged. Have you pulled the pistons out for inspection?

Hello Raymond,

Thanks for being in touch. 

On back to first principles - first check the compressions on each cylinder and report back. 

If they are all acceptable then you would appear to have reasonably covered mechanical damage issues. I’m certainly not claiming this is your issue, it could be something like a camshaft position sensor which might also have been a victim of the whole damage scene. 

Kind regards,

Gareth. 

Thank you both for your replies. we have found the problem, the DPF is blocked, we removed the exhaust from the manifold and it starts and runs.

Why the DPF would block up in such a short time we dont know yet. Maybe its destroyed inside or fallen apart we dont know yet.

 But thanks for taking the time to reply