VR6 engine ECU compatibility

[e4t vw 2]

I have a '93 OBD1 golf VR6. The current  engine ECU has part number  021 906 258 AF.

 

 

Will a engine ecu from a later OBD1 car which has part number 021 906 258 BK work in my car?

 

Both have the same number of pins but inside the circuit boards are different

[Philly-R6 28]

If you are expecting to plug the 'BK ECU into your car, it probably won't run.

 

The subtleties are in the sensors and subsequent wiring harnesses, which change over time as the systems are developed.

One change for example is the air mass sensor, earlier models had a 6-pin connection, later ones have a 4-pin connection. Other sensors have changed, too.

One other difference is the factory immobiliser which later cars definitely have. I'm not sure how interchangeable they are (they are paired with the ECU).

 

If you are up for some work, you can get the whole setup (keys, immobiliser, ECU, wiring harnesses, inlet manifolds, all sensors) from as late a car as you can and update your engine. There is plenty of information on here about upgrading to OBD2 - for example:

What is up with your current ECU, that you are considering swapping it?

 

[e4t vw 2]

The current one was liquid damaged from what is likely a result rain leaking through the scuttle...the car would randomly start cutting out and not restarting and eventually died.

I tried a friends ecu with exact same part number in my car and it fired up and ran perfect at first turn of the key!

 

With the BK ecu i also have the full engine loom too which i can compare to the one currently on the car. ALSO the BK one appears to be remapped- it has another chip soldered.

 

Is there any real benefit to switching to OBD2?

 

[Philly-R6 28]

I've not actually done a swap to OBD2, so can't really comment if it is beneficial.

Summarising other peoples reports, the headline points are:

# the faster ECU provides finer tuning

# superior idle (no separate idle valve)

You don't get more power or torque - its just smoother.

 

I only mentioned the 95on ECU setup as it is the same amount of work updating the harnesses, whichever ECU you decide to go for.

 

All VW ECU's are listed here:

http://www.vaglinks.com/Docs/Catalogues/VW-Audi_ECU_ModelsPartNumbers.pdf

Your original 'AF ECU preceded the 'BK ECU, so most sensors should be similar (both seem to be Motronic 2.9).

If you still have access to the donor car, compare the part numbers of the air mass sensor, lambda sensor, etc.