I'm actually posting this for my cousin, they did a supercoupe swap (had a whole donor motor but swapped everything onto the mustang engine following the directions in the sticky on this section), but the car simply wont idle its running WAY rich, fouls the plugs out almost instantly and when u pull a plug its SOAKED in raw gas, anyone have any idea whats going on with it. Cars a 97 sixxer.

 

I would guess it needs a tune?

 

That would be my first guess, but in the swap sticky it mentions nothing about a tune or ECU. EDIT: Cousin didn't say in the directions it needs a tune, just looked myself. Duh.

 

same type of fuel systems? return or returnless

 

Its going to need a tune. There is no way it will run properly without one. You are running diffrent size injectors, FI, and all that good stuff. The computer wont be able to do it without a tune. Trust me Im in the middle of doing to swap myself. Ive spent alot of time looking at the M90's.

Matthew

 

Trust me it needs some form of tuning, computer will not compensate for those huge injectors unless he has a maf calibrated and then the car still needs a tune to get it perfect.