RPMs dropped like a rock mid-pull on the dyno last Tuesday and I still can't figure out if it was fuel or timing.

Happened right at the shift point on a 93 octane tune, AFRs went lean for a split second and then it fell flat on its face - has anyone else dealt with intermittent cutout that doesn't show up in the logs?

2 comments

2 Comments

lilykelly24d ago

@kelly_west74 might be onto something with the pump driver module thing. Had a buddy with the same problem on his Coyote and swapping that part out fixed it clean. Ended up being the voltage sagging just enough at high load to mess with the injectors but not enough to trip a code.

kelly_west7424d ago

Honestly, I've been hearing about this exact kind of thing on a few of the Mustang forums lately. Some guys are saying it's a bad fuel pump driver module that drops voltage right at high load, but it won't log unless you're watching on a scope. Tbh, I'd check your spark plug gap too, if it's too wide it can blow out the spark at shift rpm and make it look like a fuel cut on the AFR.