For the experienced ECU gurus;

Will the engine turn over with the starter if the ECU is not present in the car?

Part 2: Can you take the ECU from another car (same model year) and start the engine in a different car?

Looking at a 2001 TT with the ECU missing. I would like to turn the engine over and do a leakdown test and listen for funny noises etc. If this passes I would think about borrowing an ECU to see if engine would run for further check out.

 

NO to 1 and NO to 2

 

You wouldn't be able to even start a tiptronic 996 Turbo with an ECU out of a 6-speed 996 turbo.

 

Thanks Markski! I was pretty sure it wasn't that simple.

Rental- Target and donor are both 6 speed cars.


I will have to see how far I can pursue, maybe I'll hotwire the starter and turn the motor over to make sure it's not siezed or makes any weird noises.

 

ECU's are all VIN locked and smarter than us.

 

News to me... I would have assumed it would work. Looks like Porsche doesn't like to make anything easy for us.

 

That seals it! Learned a long time ago never to work on anything smarter than I am.

 

I think this is a good thing. Imagine if it was possible to swap ECUs between similar cars....We would have no chance to be sure about the mileage of a used Porsche, for instance....

 

I beleive the mileage is stored in the instrument cluster, thats why you see those low mileage clusters on the "bay place" for bunches of money to take mileage off your car. However running hours are stored in the ECU. One of the selling points of the Durametric is you can read running hours and compare them to the mileage on your cluster. If there is a big discrepancy you know the cluster has been rolled back or changed.

 

zakly...

 

Cant the dealer match the DME to another car? You can do it with BMW's. What happens in the case of DME failure? I'm thinking it can be done. I would call the dealer and ask. I had 2 DME's for my M3 one with the supercharger tune and one for NA. Now I couldn't just swap them without getting it synched to the car which I had my local BMW shop do for me.

 

Yes, a TUNER can swap an ECU/DME, not the average bear...

 

The miles are read off of your tranny.... stored in ECu... the cluster does not store your miles... sure it puts on the miles on the cluster but thats it....
One can easily run a car without putting miles on the ecu.. and it will never be stored either...

 

ECU stores hours of use. A dealer (or someone with the proper codes and PIWIS) can clone an ECU to a new VIN, but the hours of use will be reset. Actual mileage is not stored there...but anyone who runs the numbers on the ECU in the future will note that the miles/hours of use will be off (ie car has traveled 20K miles in 1 hour of use.)

- bob

 

So, the truth is that when you buy a used car there's no way to be sure about real mileage of it....