ISX cm2350 low. power/poor. Fuel milage.

[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.