Over boost while jaking

[Josiah Harder]

(02-22-2023 )Rawze Wrote:  BAD DELETE programming is a plague in the trucking industry .. and almost all truck owners will swear the truck "runs great otherwise".. until just like the blown engine in that shop .. a piston goes thru the block, or it takes out a turbo or 3 .. and other horrible things set in, due to someone 's garbage-delete-programming incompetence.

Eliminate the most obvious thing (possible bad delete programming that has a high chance of being unstable) that your post implies FIRST.. and not last.. and then you can go from there.

I don't care how well you think it might run otherwise, most truck owners would swear their delete "runs great" .. all the way tot he day it blows the had gasket..or till that turbo blows up.. or far worse.. puts that piston right thru the side of the engine block!.

It "seeming to run ok" is exactly WHY the trucking industry is so badly plagued with bad delete programming that is not worth putting in a lawn-mower, nonetheless a $40,000 commercial engine.

Do the other things suggested on the forum here so far, BUT ALSO START BY assuming that program very well might be total garbage, having a heavy chance (90% chance by statistics) that it could be significantly harmful .. and quite frankly.. the root cause of your issues.

Copying the program out of that ecm (using the Calterm software) and e-mail it to me for a proper review to ensure you are not chasing something that some moron might have created in that ecm at some point.


Make sure you boost gauge is reading correctly.. 48-psi is a pretty high number there...

48-psi either on boost or during jake.. CAN AND WILL DESTROY THAT ENGINE WITH ABSOLUTELY ZERO WARNING!. Boost should never ever be above about 36 psi on that engine.. no matter what the HP/torque rating.. and jake should roughly be cresting at about 28 psi or so max.

Hey Rawze I was just reading through this and am now worried my X15 might be over boosting while jaking too. Mine is not de mandated but since I last had trouble with the truck not running due to what Peterbilt diagnosed as high exhaust back pressure because of the actuator being stuck I have been getting 38-40 psi of boost on 3rd setting Jake. I cant say for sure it was not always that high because I don't remember what it was normally at but my 2nd setting is consistently 20-22 but my 3rd setting almost seemed too high to me and now reading your cautionary comments about boost not exceeding 36 I'm worried. Unless my engine is different and that is normal but I don't want to blow anything up like you warned of so I might just avoid using the 3rd level. Also will my gross weight and level of grade effect how much boost is created when Jake breaks are on?