To start, I have a 2000 miata with a diy turbo setup running megasquirt pnp 2. Last night I drove home fine from work, parked my car, installed a catch can in between the pcv and the intake but didn't take the car out, I felt the catch can wouldn't affect anything. I started my car this morning and it instantly wanted to idle at 3000 rpm. When I let out the clutch in neutral I got it to drop to around 2200 rpm, still very high. It previously was about 900-1100. Also, when I get on it a little (above 3500) and shift, when I push the clutch in it drops to 3500, hesitates, and then goes down to 2200-2400. Finally it is deiseling out, turn it off and it continues to run for a few seconds. All of this is new, the car was running fine. I plan to undo the catch can and see if that may help, but I feel like it's not the issue. Nothing else was changed (intentionally) by me. Any advice on what to check would be great, thanks!

 

Is the catchcan sealed or does it have a breather element on it? Cuz if it does, you just introduced a gigantic vacuum leak.

 

No it is sealed.

 

Resolved issue. Though the container is sealed, it somehow must have had a leak. I will delete this thread if I can when I'm home.