Hesitation/Loss of Power problem

[blown03hd]

Just bought a 93 GT with a V2 (non intercooled) vortec SCi running 10 lbs of boost. It has a lot of bolt ons to include 42 lb injectors, edelbrock heads, full magnaflow and bbk exhaust, tremec 3550 w/ tri ax shifter, an f cam, single walbro 255 pump, etc...

In warm weather, it hesistates and loses power (runs very rough) in the mid range RPMs. I have cleaned the MAF, put in a new fuel filter, and changed the plugs (autolites), and it still hesistates. My wideband A/F jumps around a lot everywhere from 16:1 to 13:1 with no boost. It runs anywhere from 180* to 195* (water temp) when it is hot out. In cool weather, the hesitation doesnt happen.

Any ideas? Please help!

Do I need colder spark plugs?

Saint

 

[DAVESVT2000]

Might want to try the mustang forum, or the blower forum, as this is not 93 cobra related.

 

[clean93]

Has the car been tuned at all?

 

[blown03hd]

Yes, tuned safe and rich, 10 lbs of boost. Not the tune, definitely mechanical.

 

[FISHTAIL]

I'm guessing, but it sounds like a weak spark issue when the car is getting into boost and starting to load up with fuel. You still running the stock ignition system? What does your A/F look like when it starts running rough? Your fuel pressure?

Do you still have the original TFI module? Those guys like to fail when they get hot. Normally they fail and the car flat out quits running, but I had a module on my 88GT that went through this goofy intermittent failure that acted much like your describing. It would run fine until you stood on it, then it would buck and shudder until it got up to 4k rpms or so. This continued on and off for a long time before I finally replaced the TFI out of desperation and walla..problem gone. I've never had or seen another fail like that again, but it's possible that is your issue.

 

[blown03hd]

Fishtail, thanks for the info. I think it is either the TFI module or the MAF going bad. I am going to replace one at a time and see what happens.

Saint