97 cobra with after mrkt vortech v2 tuned with standard fmu

[kudzu]

If anyone could help, it would be greatly appreciated.

I have a 97 cobra with v2 vortech supercharger, it hs the standard Fuel Managment Unit. Runs great, but when it gets hot, it will replicate what i remember the older cars doing when they would vapor lock. My understanding these newer cars cant vapor lock. After sitting for about fifteen minutes, it will start rough,, have to open throttle,, get white puff of smoke. Hesitates and surges like it is missing on a cylinder. good spark on all cylinders. Chasing a ghost. no codes. will run great again next day. Fuel pressure guage on dash shows good pressure when boost rises.

any ideas what to check.

[BurnTire]

Is a 1998 a return fuel system?

If so does your fuel pressure go up under boost?

It has been a long time since I worked on an older stang.

[kudzu]

not sure about the 98,, i think 98 cobras came stock with supercharger.

but the fuel pressure does go up as boost increases.

it will run great some days, crap others, good for 2 miles,, then crap again.

[BurnTire]

Don't beat on it until you get it figured out. Look for air leaks / vacuum leaks. Check the plugs. How long have you had the car?
Brookspeed Tuning is down in your area if you need some professional help.

[brentsSVT]

I'm 99% sure none of the early models came s/c. The early svo was turbo but unless it was like a saleen or rousch no boost. Let it warm up and do a compression test for ease of mind. Check wiring at the mass air flowaswell.