Cummins x15 low boost after delete

[J_Rok]

It think your answer is in your question, you said it boosted easy 45psi before the guy “you trusted” fixed your bad delete then 21 psi after. The pros on this forum get cranky real fast with people who don’t listen. Figure out how to get that tune sent to Rawze like he asked of you and check your CAC system for leaks with a proper tool with a psi gauge if you haven’t already. I wouldn’t trust anyone with my ecm tuning except for a few select guys on this forum. You seem to be set on the fact that it can’t be the tune but that’s the first thing I would suspect.

[Onepl]

I have the same problem with my X15. Before the delete, the boost was 31-32, and now it goes up to 29 for a while and then drops to 21. Five different guys have already tried to fix it, and nothing. All sensors are new, no boost leak. Any ideas?

[marek4792]

If it wasn't done by anybody on here, you likely have a bad delete..

[Onepl]

(07-30-2025 )marek4792 Wrote:  If it wasn't done by anybody on here, you likely have a bad delete..

Can you recommend someone who can do this properly? What I've noticed is that when I disconnect the throttle actuator position valve, the check engine light goes on, but the boost returns to normal. 30-32 psi

[marek4792]

Check with "running rough"

[Techmech]

Onepl........if you just read you could most likely fix your issue. In this very tread RAWZE just pointed that the Intake Throttle valve butterfly diaphragm should be removed.
You pointed that boost goes back to normal when you disconnect the valve.

I am not saying that you should not have your program checked but at least read the whole tread twice, understand pointers given and than ask for help.