hey i am doing a tII swap into my n/a. the problem i am having is, the ecu has three plugs and two of the come straight from the harness and connect. the third plug is only about 4 inches from the firewall and i dont know what that goes to. on the n/a harness there was a plug there that connected and went along another harness that connected to the ecu and the harness continued farther into the car (possibly to the instrument cluster). can any one help

 

I'd suggest keeping all of the original wiring harnesses (NA), but it sounds like it may be too late for you. The ECU plugs on an NA or TII EM harness are the same (plug shape), and there are 2 of them. The 3rd plug for the ECU is from the front harness, which you should not have messed with. The front harness plug will come down from behind the dash. You can click the link in my sig. for detailed swap info, or just check the FAQ.

EDIT: This all assumes you are swapping within the same series (S4 or S5). You gave no car info.

 

the ecu that i took out of the car and the one that came with the motor have different plug shapes. the car is a s4 and the motor is s5(assuming cause of the intake manifold). all i messed with was the harness that goes to the motor. i have no emmissions so could i use the same ecu and harness. i assumed that i needed to use the ecu and harness that came with the motor. would it make sence if the motor is a rew. would that cause the plugs to be different shapes if the tii s5 and n/a s4 shound be the same plug shapes.

 

Plug 3 on an S4 is 5 pins wide while on an S5 it is 13. Plug 2 is 9 pins wide while the S5 is 8. Plug 1 on the S4 is 12 pins wide while the S5 version is 11.

 

If you're using an S5 engine, you've just opened a can of worms. In terms of electronics/wiring/ECU, S4s and S5s might as well be different cars. The easiest way is to use S4 TII electronics and S4 NA wiring, then just keep the S5 block, manifolds and turbo. This is an outline for that: http://www.rotaryresurrection.com/2n...o_s4_swap.html. You can't throw an S5 TII EM harness into an S4 NA car and have everything plug in. The plugs are different, and the wires are not in the same locations at all.

 

^ +1 beat me to it

 

so i should keep the n/a harness and get a s4 t2 ecu? that would get rid of the problems i am having with the plugs matching up?

 

yes, you will also need to use all of the sensors, injectors, throttle body, etc. from an S4 TII. You are going to need to premix also, unless you switch to the S4 mechanical OMP, as the S5 is electronic.

I highly suggest going back up to Post # 5 and clicking the link to the rotary ressurection instructions.