X15 surging under load
01-08-2023, (Subject: X15 surging under load ) 
Post: #1
X15 surging under load
Trying to help my neighbor out this morning and I’m at a total loss. CM2350 X15 demandated by a less than ideal individual about 6 months ago. The problems I’m going to state started about 2 months ago and can only be replicated under load. Bobtail or empty trailer you’d never know the truck has a problem.

So the truck UNDER LOAD feels like you’re riding a bull at the rodeo. The throttle position sensor is ALL OVER THE PLACE! 100% to 0% to 75% to 100% to 33% etc… When empty, no such issue. He doesn’t know which codes it threw other than a cylinder unbalance.
Peterbilt replaced the following:
- Fuel Filters
-Throttle position sensor with lead
- Fuel Pressure relief valve
- Fuel pump actuator
- ECM

After spending thousands of dollars and no resolution, he pulled the truck and it has sat since. He brought it over to me last night. Lift pump pressure is 25psi. High pressure fuel pump puts out 150ml @ 140rpm in 30 seconds (although the fuel coming out of the rail looks to have a LOT of air in it. Fuel from fuel filter has no air in it). Turbo passes on insite. Injectors pass performance test EXCEPT on the 3rd test on each injector). I only had about an hour to commit to it last night. Going to check throttle valve this morning and do an injector leak test. Just not sure where else to look. Help would be appreciated! I’m not a shop. Just a fellow trucker trying to help another trucker out. Thanks!


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01-08-2023, (Subject: X15 surging under load ) 
Post: #2
RE: X15 surging under load
The first thing you need to do is pull the program out and send it to Rawze for review. There's no point in doing anything else until the program is verified to be good or is fixed.


User's Signature: Warranty??? Yeah right, I am the warranty!!!
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01-08-2023, (Subject: X15 surging under load ) 
Post: #3
RE: X15 surging under load
Mr Rawze, would you pm me your email.


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01-08-2023, (Subject: X15 surging under load ) 
Post: #4
RE: X15 surging under load
I would bet the cans are still intact, or just a few holes in them. Truck I have torn down was having the same issues, a couple of holes drilled, along with bad programming. Rawze's contact info is at the bottom left corner of the website. [email protected]


User's Signature: 2008 ProStar, OEM 600hp CM-871, 18spd, 3:42, in framed in Rawze's driveway. Every day is a fresh new episode of, "The Twilight Zone"... Rod Serling lives rent free in my head. I can smell the Chesterfields.
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01-08-2023, (Subject: X15 surging under load ) 
Post: #5
RE: X15 surging under load
Thank you. I sent it to rawze. It was reviewed by another reputable tuner. They claimed it was “not terrible” but I will wait for rawze to review it


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01-09-2023, (Subject: X15 surging under load ) 
Post: #6
RE: X15 surging under load
Leak test loses about 4500ish psi in 60 seconds. Can I perform this test by capping off 5 injectors at a time without damaging anything? Would like to see if there is a difference across each injector. Throttle valve is open so I can rule that out


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01-09-2023, (Subject: X15 surging under load ) 
Post: #7
RE: X15 surging under load
I doubt it will start if you cap off 5. Try 3 at a time.


User's Signature: Warranty??? Yeah right, I am the warranty!!!
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01-09-2023, (Subject: X15 surging under load ) 
Post: #8
RE: X15 surging under load
(01-08-2023 )GeArHeArT Wrote:  Mr Rawze, would you pm me your email.

send engine program to [email protected] for reviews, etc.


User's Signature: ->: What I post is just my own thoughts and Opinions! --- I AM Full Of S__T!.
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01-09-2023, (Subject: X15 surging under load ) 
Post: #9
RE: X15 surging under load
(01-08-2023 )GeArHeArT Wrote:  Thank you. I sent it to rawze. It was reviewed by another reputable tuner. They claimed it was “not terrible” but I will wait for rawze to review it


Sure, i have seen far worse myself.. but the "not terrible" statement is a mis-judgement in my book on this one.

Here is what I see at a glance...

* engine has wrong CPL program in it according to the ser#. Program is not compatible with this engine, turbo, nor the vehicle itself. -= this alone should have been a big red flag. No wonder it does not run very well, and this can cause problemns + eventual component failures.


* Tune or not.. There are multiple mis-fire codes. This is not normal at all and is an indication that something physically is wrong too. Injectors going bad>?.. maybe but more likely a clogged exhaust pressure sensor, or its feed circuit thru the thermostat housing.. or the tube off the manifold is damaged/missing, etc..

* ATM manager signal for the def gauge is not set to send the signal any more. This is not a big deal, but this can be improved, and the def gauge made to read a value in the dash again.

* The non-egr-ref2 table (fresh air inatke air flow request table) is zero'd out. This is a mistake from out-dated programs of the past. The ref1 (EGR air flow request table), not the ref2 table, is the one needing to be zero's out.

* some engine mode tables were missed. engine may change operating states randomly with unpredictable power/boost, efficiency changes etc..

* The main Nox tables were missed. This messes up injection timing, fuel air mix.

* Amonia allowance tables set the wrong direction. They are maxxed out instead of set to 0. This is another common mistake of out-dated programs of the past. This can messes with injection timing, fuel air mix.

* turbo not set high enough at idle. Another mistake of out-dated programs of the past. Will cause vacuum on intake .. and has been shown to have a high chance to cause the turbo to seep oil into the CAC/intake at idle.

* Turbo is set to over-boost the engine at 38+ psi. An X15 cannot take this much boost.. it will tear the engine up.. and the turbo. Anything much above about 32-33 psi on an X15 will lead to eventual engine and/or turbo damage.

* Power/torque set to 605HP and 2050trq. This is harsh on a mid-tier engine build that was only set for 450HP hardware initially.

My thoughts...
Looks like it was a valiant attempt to copy-cat the MM process by someone. A lot of it was done fairly well.. but at the end of the day, the program is still harmful and inefficient due to being the wrong program, the turbo tables being way to zealous, and the 605HP-2050trq shoved into a mid-tier engine that was supposed to be 450HP.


If the boost settings had been fairly ok .. the Nox tables were done properly., and the program had been correct for the engine ser# and vehicle.. then the "not terrible"would have applied ... along with a "way out of date" warning too. However, since those 2 mistakes are in fact harmful, I say that it is overall a bad program.


There is also a separate problem on the engine with mis-fire codes that is not normal at all. Maybe a bad exhaust pressure sensor, or its circuit going thru the thermostat housing.. or perhaps injector damage that has set in due to overly-high hp/trq demand for a mid-tier injectors, etc. build.


User's Signature: ->: What I post is just my own thoughts and Opinions! --- I AM Full Of S__T!.
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