Hi, my 2008 A4 3.2 Quattro Tiptonic with 118K miles on it has a lot of issues since I bought it 3 years ago. Currently I am experiencing a very strange no-start issue.

The car has a crank and no-start condition that I'll try to describe. At the first start like in the morning or after a long period of "rest", the car stars almost well but when I leave it for more than 10-15 min the cars does not start again. It cranks and cranks and cranks without any start. But sometime after a lot of tries, I saw an interesting pattern. When I put the key on position ON (before ignition), I can hear the fuel pump priming, the throttle body initializing,... and the "break pedal" logo/light ON on the gear lever plate. Which is normal but after 5-6 seconds, the process start again with the fuel pump priming, the throttle body, etc. If try to start the car during this cycle/pattern, the car cranks and starts but stalls when the 6ish second is reached - the cycle/pattern restarts. I tried to rev up to 2,000/3,000 rpm to keep the power high but the car still shuts down after 6ish. Also, I plugged a battery booster to be sure to have enough voltage but nothing better.

I always have a P0606 error code which is the ECU. The car had a diagnostic by an independent services center specialized in German cars and they ended up by a fuel pump issue. So I replaced it but nothing better. After a second diagnostic they replaced the ignition switch but nothing better. So they ended up by saying the ECU should be replaced.

The thing is the car is running almost great when I can start it - yes sometime I can start it. Because I do not want to spend $2,000 or so in a new ECU I started to look to buy an used one and to have an immobilizer defeat/clone on it. So when I opened the ECU box to get it I saw that the ECU was previously removed. There is new bolts and tools scratches on the metal part which is holding the ECU connectors. Normally there is no bolts but a kind of bolts without the head. So because I bought the car at the same Audi dealership than the previous owner bought it brand new I have all the records since the first day. At 20k miles they noted that the ECU was updated, nothing more.

Also, with VCDS I checked all parts (ABS, immobilizer, transmition, etc.) of the car to find another error codes but nothing except the one(s) relative to the engine.

Have you ever seen this kind of issue? Do you think I should try to buy a use ECU for $150 to give a try? Any suggestions?


Some details

New parts:
- sparks plugs
- coil packs
- throttle body
- gaskets
- coolant sensor
- gas pedal
- fuel pump
- ignition switch
- upstream O2 sensors

Tested parts:
- camshaft sensors (good)
- MAP sensor (good)
- camshaft timing solenoids (good)
- all fuses (good)
- all relay (good)
- battery (good)
- alternator (good)

Need to be tested:
- downstream O2 sensor
- high pressure fuel sensor


Thanks