I've been helping a friend track down a problem on a truck that has a stock crate 350 with tpi swapped in. Its running $8D code on a 1227730 pcm, stock heads and cam, advertised HP was around 250. New injectors, distributor, fuel pump, throttle body. It runs great until it hits 3800 to 4000 and then it stops accelerating and acts like there is a soft touch rev limiter hooked up to the ignition. Its a very peaceful cutting out, not the violent engine cutouts followed by backfiring that I've experienced with other engines.

We've checked fuel pressure and its at 41 psi at atmosphere and responds the way you would expect it to when engine vacuum changes. Pressure never drops off when it starts cutting out.

swapped distributors, tried every $8D bin I could find setup for a 350.

Is there an obvious reason why it is a consistant 4k cut out? Any rev limit in the $8D code? I couldn't find any documented in the dissasembly.

This is frustrating

 

There is a cutout but it shuts down the fuel based on rpm.
Stock is 10031 rpm.

You need to datalog it.

 

I agree about datalogging, but I didnt have the serial definition on my laptop at the time for tunerpro rt. Is there a better datalogging software for these? I was stuck using a snapon scan tool, and scrolling through the values wasn't really worth the effort.

 

I use TunerPro RT. It's the best i've used so far.

We can start throwing suggestions out there left and right but a problem like yours.....is best left to a datalog.
BTW - the "rev-limiter" is in the memcal and not the ecm. If you were only changing ecm's and using the same memcal, the problem will follow with each ecm.