ISX won’t Regen properly

[matthewharrison2011]

Hi guys, first post here.

I’m a mechanic at a privately owned construction company. They want things out fast & don’t usually give you much time to figured these things out, but anyways...

Currently working on an ISX CM22 or 2350. Currently it has engine code 1921, basically the soot load in the DPF is at level 3 and the truck wants a computer generated regen.

When trying to regen through insite the truck does go into regen, but the exhaust temp never gets to 500 or more so diesel injection in the aftertreatment system never happens, and nothing gets hot enough to properly clean the filter.

I did notice this evening that when the exhaust temps are up over 302F the inlet NOX sensor reads, but the outlet never registers. I had the truck up to 400F on the outlet this evening with the outlet NOX sensor still not registering a reading. My guess here is that there is a CANBUS issue because in most cases a ground or 12V supply issue usually throws a code on insite. I was at the end of my shift so didn’t get a chance to start testing voltages properly yet. Seems to be an issue that needs to be resolved regardless.

What I am wondering is if the outlet NOX sensor would be enough to cause the ECM to pull back on creating exhaust temperature. I realize in a normal operating state its more plausible because heat creates NOX & possible engine adjustments combined with DEF injection will reduce those emissions, but when doing a regen through insite would it disregard that portion as it’s going to be burning hotter than usual and in a cleaning state?

Haven’t seen any major leaks on the exhaust system, EGR valve seems to be responding properly according to insite, turbo is new, manifold done recently.

Going to figure out the outlet NOX issue but I’m afraid that’s not going to solve the problem. The engine sounds fine under normal operation, but when attempting a regen it just doesn’t sound right to me, and I personally think that’s where the problem is coming from.

Only engine tests I’ve done is the insite injector performance test and a bit of monitoring different values through insite, everything passed on the performance test. Haven’t tried a leak down test or much else outside of that yet.

Probably missed some info, but curious on what your guys’ thoughts are.

Thanks in advanced for any help.