ISX 450 Intermittent Mystery Derate

[Allaroundag]

After watching Rawzs' old video about sensors and carbon I am going to do some cleaning and go from there. Everything he describes is pretty spot on. Truck has 245k miles, just like he mentions as well... I'll update after doing some more cleaning. The IMAP sensor was caked when I cleaned that a couple weeks ago too. I have no problem replacing sensors if that's what needs to happen (and will just plan on it). I just wonder why it runs well and then intermittently goes to heck. Fuel economy has always sucked too... as he mentioned. I wish I had discovered this place sooner.... like before I purchased this thing! Thank you all.