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I was thinking from my thread back in April that with all the mismatched parts on the 351 to have it be mustang A9P controlled would need to be tuned for best performance, regardless the rest of the drivetrain.
The A9P has the ability to "learn". That's why the Stang guys don't have to get a tune when swapping cams...streetable cams and T-bodys. My SN95 ECM is not so forgiving on the "learn" side. Even after the tune I needed to add a few things to make my W happy at idle. The cam needed more air than the ECM could tell the IAC to provide. Took time to figure out and make it happy. Used an idle air bypass which is adjustable and fixed all my issues.
My guess is the ECM is learning but you should still get a tune as the W is 50 more CI than the 5.0 and a direct tune is better than the "learn" which is a fancy way of saying compensate.
Even if you think it runs good after the tune the C4 is still going to generate lots of heat due to the big tires and gearing. I suggest a well working add on trans cooler to buy time but in the end the heat is being generated due to slippage and over time it will die. Gears will fix that by putting the C4 back in the original RPM band it was designed to run in. It will also put that W in the RPM band it was built to make power in. It's a win win
Gearing is definitely holding you back, automatically that is a 30% reduction in power to the ground, no tuning in the world is going to get that back. To get back to stock is 4.56, for todays standards and speeds that is a bit deep, 4.10-4.30:1 is probably more appropriate, if never interstate driving, dive full in and get 4.56's.
Then there is weight, have to remember the old drag racers adage, 100# is .1 of a second, wanna go faster cheap? Start cutting stuff off.
The A9P has the ability to "learn". That's why the Stang guys don't have to get a tune when swapping cams...streetable cams and T-bodys. My SN95 ECM is not so forgiving on the "learn" side. Even after the tune I needed to add a few things to make my W happy at idle. The cam needed more air than the ECM could tell the IAC to provide. Took time to figure out and make it happy. Used an idle air bypass which is adjustable and fixed all my issues.
My guess is the ECM is learning but you should still get a tune as the W is 50 more CI than the 5.0 and a direct tune is better than the "learn" which is a fancy way of saying compensate.
Even if you think it runs good after the tune the C4 is still going to generate lots of heat due to the big tires and gearing. I suggest a well working add on trans cooler to buy time but in the end the heat is being generated due to slippage and over time it will die. Gears will fix that by putting the C4 back in the original RPM band it was designed to run in. It will also put that W in the RPM band it was built to make power in. It's a win win