Dyno report

I took my car to PRT Performance yesterday. My best pull on their Mustang Dyno was 115 hp at 7000 rpm. I was pleasantly surprised that the hp curve kept rising up to 7K. My old motor made 109 hp on a Dynojet. When I adjusted for the lower Mustang readings, this motor is making 129 Dynojet horsepower. Torque is about 110 ft/lb.

However, my motor is running lean. It could make more hp with a richer mixture, maybe 5 to 10 hp, says the dyno operator. I didn't get his name. What can I do to make the mixture richer with my OEM ECM? Or, is a Megasquirt my only option? AFR is about 15:1 at 4750 rpm and 13.2:1 at 7000 rpm.

115 is strong on a Mustang dyno. 15:1 is pretty lean but at least it gets richer at high RPM.

AFPR, or use a piggy back fuel card like they do on the FI cars

Bigger injectors?

I thought the SM guys use the AFPR to lean the engine out at high RPMs, as the stock ECU typically adds too much fuel.

When was the last time you changed your fuel filter, start with the least expensive thing first.

Then you might look at the fuel pump. The stock one should be plenty for the stock injectors. I put in a Denso when I was having starvation issues at MSR-C. 1. It requires custom cutting of the rubber mounting piece. 2. The sock is a little different. I've since learned the Mazda fuel sock is better and reduces the fuel starvation issues. But Mazda only sells the entire unit at $250 on Mazdaspeed.

Have you had your injectors serviced recently? Usually dirty injectors add too much fuel as they stick open, but you may have a bad injector. They can measure them.

You might also replace the stock FPR. In SM, before the AFPR, they used to squeeze them in a vice to lean them out. Could someone have adjusted yours?
Without a MS, a bigger fuel pump and more Dyno time, you won't be able to control bigger injectors.