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-   -   '03 Cobra and '99 F150 questions (http://forums.mustangworks.com/showthread.php?t=20758)

dalemarlow 03-15-2002 02:36 PM

'03 Cobra and '99 F150 questions
 
Here are some questions about these vehicles I have.

1. Do you think a '03 Cobra will take 125-150 hp shot of nitrous if properly tuned? As you are surely aware the new Cobra has all forged inerds and an iron block. The trans is the Tremec T-56 six-speed.
2. Can you explain power shifting during a drag race?
3. What would cause an engine to hesitate while trying to accelerate while in load conditions? The truck (supercharged 99 F150) feels like she is missing. I changed to NGK plugs one step cooler but that didn't help either and gapped at .035. My EGT is about 1000degrees at 2000rpm. The hesitation comes on just as the boost guage reaches the 0 and lasts till 3 psi. It goes away above that. Fuel pressure is about 47-50psi during this load condition (has a boost adjusting FMU 4:1).

93GTDIN 03-16-2002 01:12 AM

I just had the exact same problem. FMU's are tricky pieces of equipment that must be calibrated to your situation. On my 93 GT, when I hit it on the highway, from 0 - 3 PSI it hesitated and sometimes shook. I also had thick smoke that reeked of gas coming out of my tailpipes. I was able to deduce that my FMU was jacking up the pressure to early. The way I fixed it was by unpluging the FMU. My car, at stock pressure, had enough fuel to not run lean. Your truck may be different, so i would try the following things:
Make sure the vacuum line from the FMU to the tree has a check valve and more importantly, a vacuum restrictor. This will stop the FMU from putting the fuel system under pressure prematurely. Also, try opening your FMU (turn left) in 1/4 turn incraments. You should hit a sort of "sweet spot" that will work best for you. If you open it up all the way and the hesitation is still there, 4:1 might be to much for your situation. At this point, i would try simply unplugging the vacuum line to the FMU (No need to unplug the fuel lines) and give it a run. It may ping, so be careful. I would highly recommend an a/f gauge for your setup.

hope this helps
dino

91LX2Bfast 03-17-2002 07:57 PM

With only 8psi stock, it should handle a 125-150 shot with a proper fuel system and tune. The tune and fuel are going to be so important, but it shouldn't be hard to figure out. I can't wait to see these new cars.
Two more years of college... then maybe, just maybe, I will own one for myself:p

SLOW 97 03-18-2002 09:55 AM

Just out of curiosity, do you own an '03 Cobra or have one because they don't come out until May/June. It's actually running only 7 PSI. 91LX2BFast is right though, with a proper fuel system it should easily take a 150 shot. With forged internals it should be fine. As for powershifting, in a drag race, just keep the pedal to the metal and and depress the clutch when you want to shift. Shift points depend on the car. Pretty simple.


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