10/02/2026
A bad tune snaps cranks.
I've been avoiding talking about this, trying to find anything else to support a different theory as to why Blocky's crank was split. No matter how I try to word it, no matter how hard I tried to keep my analysis unbaised, there is no way what I have to say won't sound biased. I'm afraid that the following will come off self-serving and as an attempt to sell tunes. That isn't my intent...
There is no way around it though, a bad tune stood the rods on end, opened up the bearing clearance and eventually resulted in the crank being split.
I don't know for sure what tune is on the ecm, but there are three critical areas that were modified dangerously. The owner of the truck thought they were helping their engine by deleting. That was not the case.
The three critical areas that drove this engine failure:
Timing
Torque to Fuel
Torque limiting.
In terms of timing, without egr gases, the stock Cummins timing is too advanced. The timing on this delete tune was up to 1.5x more advanced than factory Cummins. This was standing the rods on end. It would have also made it burn clean, have very clean oil and be very responsive. It must have been quite a hoot to drive like this.
Torque to Fuel is a table that tells the ecm how much fuel it takes to make a certain amount of torque. A cheater way to make power is to skew this table up. The problem is, this table is supposed to only be a reference table, generated from real world testing by Cummins. Think of it basically as: How much fuel does it take to overcome parasitic losses and acheive the requested output torque.
Finally, torque limiting. Rather than use the torque management to put a proper curve on the engine, this tuner just set the torque to maximum all the way through to the end of the rpm span.
You'll hear me go on and on about how getting into RPM helps protect these engines, so on it's own that isn't really the problem. However the torque ramp, through the most dangerous areas for the engine was extremely aggressive. This would have pushed the ecm into more advanced timing. The modified torque to fuel, again pushed the timing forward for the amount of fuel being burned.
If you combine elevated torque, plus a torque to fuel table skewed to make the ecm think it needs more fuel for the torque, it's a recipe for disaster.
Very sad, very very sad.
