SS M90 - Hesitation Issue Solved
 

I know some of you guys have SS M90 kits like mine- and I know that EVERYONE with the SS M90 setup has dealt with hesitation issues at cold start. I believe that I resolved mine this weekend and wanted to share.

I followed ZZP's instruction to the T when installing my kit. According to their instructions, the stock L36 MAP sensor should be connected to the vacuum line which connects to the throttle body right after the throttle plate. While I suspected this configuration as kind of strange during installation, I trusted that ZZP knew better than me and followed the instructions. I assumed it was an L36-style MAP sensor quirk or something that mandated that it be installed here.

Fast forward a few months: after troubleshooting just about everything else while trying to resolve my hesitating-when-cold issue, I decided to relocate the MAP sensor. I bought a vacuum T and attached it to the vacuum port on the lower intake right below the supercharger snout. Previously, only the fuel pressure regulator had been connected there. I connected the fuel pressure regulator to one side of the T and the MAP sensor to the other. I capped off the open vacuum line from the throttle body.

So far, the hestitating-when-cold issue seems to be gone! I've got my fingers crossed, but so far so good. I think that the MAP in the location as specified by ZZP caused the PCM to kind of "freak" out at initial start up, which is why the car hesitated (the hesitation on my scans was a total pull of timing, into the negatives).

Cool....I didn't know I was going to race a car with a hesitation problem. ;) Seriously though...did you run your solution through ZZP...might be a downside to your setup...I wouldn't want you to blow your stuff up...

hey i just did the ss m90 sc kit from zzp install and have a question i did the port under the snout to the map and fpr via the t fitting

the boost actuator has a top port plugged in tot top of the sc and i noticed there was a botom port, what should be plugged in there?

im at -17 boost and can figure it out