I recently swapped from a N/a S5 to a turbo S5. I did the rebuild myself (with my trusty Haynes manual and bucket!) with running into problems here and there I seemed to figure them out but this one is possibly beyond me? after the rebuild it was time to start it up, and....It didn't go so well. It would start with a little starting fluid and stay running but wouldn't idle and if it dropped to 1k rpm would sputter and die. So I back probed the ecu for the 4 injectors and spun the dash pot by hand and watched as the primary for the 1st rotor fired but got nothing for the 2nd rotor. I also heard the clicking of the injector. As a side note I also checked spark from the coil packs and everything seems to be good on that end and I had the fuel injectors flow tested and professionally cleaned. So all in all what would cause the 1st primary to fire but not the 2nd?

Thanks for the help, Zack.

 

You're probably using an N374 JDM ecu, and that is why you have no injector pulse to the rear rotor. This is why we say you cannot use the JDM ecu in a USDM car.

You can use a JDM ecu that has been chipped to remove boost cut, OR you can find a USDM N370 turbo ecu.

 

Yes I am using the N374 ecu. I was told the ecu was working properly and I thought even though it wasn't firing the 2nd rotor it was still firing on the 1st that it was something else? Also as a side note I can't find a N370 ecu anywhere or it's just my luck that I can't find them..