ISX cm2350 low. power/poor. Fuel milage.

[DPS567180]

(02-25-2025 )JimT Wrote:  A few thoughts:

Something to check which I experienced once. The rubber/silicone elbow going from the intake manifold into the air compressor wore through and started leaking right at the corner of the 90 degree bend. Gave me a whistling sound and low power. Was hard to find because of it's location and the fact that it wore through from the inside out (probably due to soot abrasion). Maybe not your problem, but might be worth inspecting.

Also, how's you DOC, DPF and SCR? Problems there, even minor, could cause the ECM to compensate resulting in what you're seeing.

Finally, partially related to the DPF, I've also had whistling sounds come from bad exhaust bellows that start to leak. Any leaks in the exhaust system can throw off sensor readings for the aftertreatment system and cause the engine to operate poorly. Everything seems fine because sensor data is in range, but the ECM is working with inaccurate data.

I checked the air compressor just to make sure but the air compressor does not connect to my intake manifold It pulls air from my intake pipe right next to the engine air filter.
My after treatment system seems to be working okay. My DEF injector went out about 6 months ago and had it replaced no issues since but I do notice the DEF fluid light flickering sometimes but every time I look in insite there are no codes or issues. I just ran the regen analyzer last week and everything passed.

[Rawze]

(02-26-2025 )DPS567180 Wrote:  

(02-26-2025 )SquareOne Wrote:  Man, there are much more qualified eyes than mine who will be commenting soon, but that RPM vs Acc position jumps out at me.... These engines do not like to be lugged (basically high boost and low rpm (as in 1350 or less). I think the highest I'd seen was around 1580rpm. Most of the time it appeared to be WOT as low as 1115 to about 1450ish.

When we're running our trucks, we keep boost low and rpm high....1500+ unless there is minimal load. This will certainly help with longevity and mpg. Not saying it's the cause of you issue you may have, but it's certainly a start.


This is some parameters noticed in your vid others will be searching for at WOT...

CBL_Fuel_State - 47
_Engine_Speed - 1245
Total_Fueling - 267.97mg/stroke
CBR_Chi_Mode_Status - 0020
CBR_Chi_Table_Mask - 00000006
VGT_Actuator_Position - 43%

At least you understand some of it I have no idea what I'm looking at for the most part. Lol would it be the programming that will cause that issue? I've never changed anything except for the speed limiter on this thing. As far as I know this is the stock programming.

== the engine is being lugged below 1500 rpm. it cannot make full power like that no matter what you do.

== fuel state 47 = its giving you full power output for the engine mode that it is in, and nothing is holding it back.

i.e.> CT is not reporting anything other than the engine being lugged under 1500 rpm where it is completely unable to make full power.

also make sure the egr valve is not hanging open.

[DPS567180]

What can I do to correct that? Is it a programming issue or a mechanical issue?

[marek4792]

Does your engine have a throttle body on the intake? Read on here few months ago someone had theirs partially closing choking off their engine slightly? Not sure of the outcome? Maybe worth looking into it's commanded vs measured position if equipped.

[Rawze]

(02-26-2025 )DPS567180 Wrote:  What can I do to correct that? Is it a programming issue or a mechanical issue?

== ensure your egr valve is not hanging open.

== ensure your intake throttle valve is not hanging open.

== stop driving it below 1500 all the time and lugging it to death. Below 1500 is the bottom 1/3 of the working range of that engine. That engine can run at 2100+rpm for the next million miles, and it will not hurt it. The 1650 -1750 rpm range is the center-point of its operating zones, where it lasts its longest.

There is a plague of trucks out there that are geared waaay too tall for their application. Also, Auto-shifter trannies are programmed to luge these engine to death these days too. - Its been a problems now for about 10+ years, and only getting worse. - Personally, it seems that by advertising they can run that low rpm, the engine makers are somewhat trying to make the engines last only long enough for the warranty to expire? .. but that is just my own thoughts.

[DPS567180]

(02-26-2025 )Rawze Wrote:  

(02-26-2025 )DPS567180 Wrote:  What can I do to correct that? Is it a programming issue or a mechanical issue?

== ensure your egr valve is not hanging open.

== ensure your intake throttle valve is not hanging open.

== stop driving it below 1500 all the time and lugging it to death. Below 1500 is the bottom 1/3 of the working range of that engine. That engine can run at 2100+rpm for the next million miles, and it will not hurt it. The 1650 -1750 rpm range is the center-point of its operating zones, where it lasts its longest.

There is a plague of trucks out there that are geared waaay too tall for their application. Also, Auto-shifter trannies are programmed to luge these engine to death these days too. - Its been a problems now for about 10+ years, and only getting worse. - Personally, it seems that by advertising they can run that low rpm, the engine makers are somewhat trying to make the engines last only long enough for the warranty to expire? .. but that is just my own thoughts.

I will pay more attention to my habits Check EGR valve and see if that changes anything. It seems I can't get above 1500rpm no matter what I do. Also this is an old Swift truck 400 ST. Are there any settings and insite that I might want to look at to make sure that fleet programming doesn't have any limited?

[Rawze]

(02-26-2025 )DPS567180 Wrote:  ... It seems I can't get above 1500rpm no matter what I do. Also this is an old Swift truck 400 ST. Are there any settings and insite that I might want to look at to make sure that fleet programming doesn't have any limited?

Those fleet trucks have programs that are locked down into oblivion. The gear-down protection and all the other garbage fleet settings need to be removed to get rid of that engine killing 1500rpm bulls#it.

[DPS567180]

Okay I think I found my issue. At the very least this is an issue. I did a parked regen today and when I looked by the exhaust there was white sit on the ground and residue on my tailpipe. I immediately thought it was my DEF injector failing again but when I checked it there was no crystal build up and I have a little cheap borescope and there was no sign of buildup inside the decomposition chamber. It's not coolant I've done a pressure test and I have no loss so I don't know what it could be but I'm assuming this is a problem.      

[JimT]

(03-05-2025 )DPS567180 Wrote:  Okay I think I found my issue. At the very least this is an issue. I did a parked regen today and when I looked by the exhaust there was white sit on the ground and residue on my tailpipe. I immediately thought it was my DEF injector failing again but when I checked it there was no crystal build up and I have a little cheap borescope and there was no sign of buildup inside the decomposition chamber. It's not coolant I've done a pressure test and I have no loss so I don't know what it could be but I'm assuming this is a problem.

hard to say for certain.

Could be ash loading up the DPF and it just happened to get blown out while doing a parked regen. High ash load in the DPF will cause performance problems as it restricts exhaust flow. Removing and baking the DPF usually removes built up ash, but it doesn't fix the potential causes. Coolant is one, burnt oil could be another, especially if you're adding something to the otherwise "low ash" modern engine oils (probably the biggest reason to avoid adding some gear lube to your oil for engines with DPF's intact). ECM estimates ash load but you can monitor exhaust backpressure sensors via insite to see what's what. Though it will be low/lower right after a regen.

Could in fact be DEF that passed through or that burnt/melted away from having previously built up on the SCR filter. Maybe it had been building up slowly due to a small leak then the parked regen brought exhaust temps high enough to burn/melt off the buildup. Slow buildup on the SCR filter could also lead to your problems as it slowly restricts exhaust flow until a something, maybe a regen, kicks the temps high enough to clean it out. Maybe inspect the DEF doser for signs of leaking?

Also, based on viewing the picture, it could be white spray paint on the ground. Hard to say from this side of the keyboard, though ash would be my first guess.