I am having inconsistant performance issues with my 347. Have been playing with fuel pressure, timing, tps and switched to a trickflow track heat intake with 1" spacer. Still dont seem to be performing like it should. I am wondering if the ecu (EEC-IV) needs programing for all of the mods. Any ideas?

 

yup that would be the best bet...i hope my 331 wont have that problem.

 

whats it doing? got any track times or dyno runs?
what makes you think it isnt performing how it should?
have you sprayed it yet?
mabye you just got used to how fast it is, every spring when I start to drive my stang it amazes me for a couple months then I just want it faster, I get used to it and feel it should be faster

 

why would you spend countless thousands of dollars on a motor build... and NOT tune it?

I swear, you guys are retarded!

 

I have not sprayed it yet, trying to get it right on motor 1st. I have done some research that said increased dispacement needs eec reprograming for the extra breathing.

 

Even with a H/C/I swap it's going to need tuning! That should be next on your to-do-list. Quit monkeying around with that hotrod and get it on the dyno and have it tuned.

 

It may be time to throw away the efi crap and put on a demon carb and victor intake.

 

DUHHHHH if your gonna mess wit the fuel pressur and the timing of corse your gonna need to upgrade the ecu or else the compouter is gonna read everything wrong and it will mess wit your perfomance