91 octane hard startup

[MistrMackey]

I have a stock 99 gsx which I recently purchased. I've been doing research on DSM's for a while but can't seem to find anything on this subject. It seems as if when I run 91 octane premium in my car every few start ups the rpm's pulse from 250 to 500 and sometimes it dies if I don't rev it up . The car runs sluggish and it seems as if I'm loosing power , the car honestly pulls like a 98 civic ex , stock I haven't dyno checked it or anything but just seems like it is having some sort of issues. However when I run 93 octane the car hasn't had a startup issue yet but still the car runs sluggish, The car makes boost fine drives fine but the service engine soon light has come on and that code is a Evap Emissions System MAJOR leak.

 

[pdbracke]

boost leak test seems to always be the best way to start.....

 

[russ96gst]

^^I agree, sounds like a boost leak to me, would cause all of the symptoms you mentioned.

 

[MistrMackey]

Thats what I thought too I had planned on doing one but had a dsm guy look at it and he didn't think there was one but I'll have one done this weekend anyways thanks.

 

[russ96gst]

^^^you cant just "look" and tell if there is one, last time I did a BLT there were multiple leaks and everything "looked" fine. I zip tie all of my hoses.

 

[MistrMackey]

He didn't just look at it... Obviously you won't be able to see a leak.