Hi

My friend is working on 1.8t to 2.7biT swap in Audi A4 MY1999 (m3.8 ecu). 2.7 engine comes from Audi A6 MY2002. After swap and connecting all cables there is a few problems. First- there is no throttle response. Engine starts but accelerator is not working (idle speed is ~2000RPM) . We checked all wires from throttle pedal to ECU- everything is fine. Can it be caused by ecu which was working with auto transmission? We haven't recoded it yet. I also think that there can be a problem between ECU and instruments cluster. Few months ago I changed faulty ecu in VW golf 1.9TDI. I changed ECU with CAN for non-CAN ECU and there was identical problem- no throttle response and high idling. But it was opposite situation- ECU without CAN and instruments with CAN. So, can this be a reason in this situation?

Second problem is no communication with ECU by OBD, so we can't recode it. Where to search for reasons? We can connect i.e. with ABS or airbags, but VCDS can't connect with ecu. Is there difference between comunication with m3.8 and me7 ecus by OBD? Or maybe its caused by some fuses?



I will be grateful for your help

Regards

Pin on small connector needs power ecu side.

Unplug the ecu and verify you have chassis ground, 12v+ constant, and 12v+ ignition at all pins you are supposed to have power. We recently did an AEB to AWM conversion and I believe we had this same issue from what I recall. We also had to code out some of the can-bus systems in the newer ecu due to the car having an older k-line instrument cluster, and ABS module, whereas the newer ecu uses can-bus to communicate with those. Do you have a wiring diagram for both ecu's and both chassis? It shouldn't take you very long to figure out the first issue, and then you'll most likely have a few more after that to resolve.

Thanks for help. I have wiring diagrams and will be fighting today

Where do you get the wire diagram for this swap?   I cant find them anywhere.  I did the 2.7 + manual swap into a 2001 audi a4 1.8t auto avant..    cant get a link to obd2,ecu nor power for the fuel pump?   Need help..