Tuning the Ford Mustang Coyote Engine

Tuning the Coyote engine in our S197 Ford Mustang has proven to be a bit more difficult than we originally anticipated, but hopefully we found a solution thanks to Church Automotive Testing. Our Project S197 Ford Mustang has been on a hiatus while we’ve been trying to figure out its issues. Our newly upgraded Coyote engine was suffering from a disappointing power curve and very poor driveability. Despite going to several local tuners, the car still ran poorly suffering from a very unstable idle that would occasionally run away, zooming to 3,000 plus RPMs. Not exactly and ideal or safe situation.

In addition, the car suffered from poor throttle response. It didn’t seem to matter if the car was at 50% or 100% throttle, it all felt equally crappy. This made it impossible to modulate the throttle, not the greatest thing when trying to navigate corners and rev matching. Even the traction control was not working right, modulating very violently. The car also had very little power below 3,000 RPM.

In an effort to correct things, we went to our favorite local tuner Church Automotive Testing who was confident they could fix our car’s issues using HP Tuners latest Ford tuning suite.

We figured part of the problem was the huge, oval, single blade Ford Performance Super Cobra Jet throttle body we were running. We replaced the huge single blade throttle body with this Ford Performance 65mm Cobra Jet dual blade throttle body, part# M-9926-CJ65.
Our new throttle body has twin 65 mm throttle blades instead of one huge oval single blade. The Ford Performance piece is pretty impressive, machined out of a piece of billet aluminum and is nicely polished.  The parts leading to the throttle blades are smoothly contoured for good airflow. Even though the throttle area is reduced over the big single blade throttle body, when combined with the Cobra Jet intake manifold we were running the dual blade throttle body will still flows substantially more than stock – to the tune of 1,517 CFM!
To switch throttle bodies, Howard first removed the intake tube. This literally took seconds.
Next Howard removed the connectors leading to the drive by wire stepper motor and removed the 4 bolts holding the throttle body to the intake manifold.


  1. Just a couple questions:

    1) Regarding the ford racing (big oval) TB, are you saying that with even the smallest throttle input it was allowing two much air for the ECU to compensate, or was the poor running more a factor of the other tuners inability to map the ECU?

    2) I guess this depends on your answer to the first question, but if the cause of the poor idle, lack of power, …etc was tuner based, why not go back to the bigger throttle body?

  2. It baffles me how people can confidently take money to tune someone else’s car if they can’t even get the basics right. There’s no excuse on a modern engine with built-in knock detection to have a timing table advanced enough to cause knock. I understand the ECU in that mustang is much more complex than the Megasquirt in my Miata, but the basics of solid reference VE tables, timing, accel/decel enrichment and idle control are basic things that a tuner needs to know.

    1. You’re missing the fact that there are multiple VE maps. GenIV GM small block V8 engines don’t even use VE maps. Instead there are a bunch of 2D tables. EFILive did come up with a GUI called virtual VE, so the tuner is able to treat the tune as though it had an actual VE map. You then allow EFILive to generate all the changes to the 2D tables and voila, car is tuned. I can’t imagine what the GenV stuff is like. Comparing standalones or even early OBDII computers to what’s out there now is apples and dog shit. I’m with you on the knock, that’s unacceptable, but I could totally see how everything else that was wrong could have easily been entirely due to outdated software like Mike said.

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