C15 down on power!

Also, use actual cat filters on fuel at least, it makes a huge difference on my 3406e

Also, you say both c15 and 3406e, those are very very similar but doesnt tell us what it actually is, such as "1lw" or "6nz" the engine prefix.

 

Mkay, my 3406e (technically a 5ek, but had a 1lw ecm in it so cat rebuilt it to that, i have to say, i had fairly similar issues to yours on donaldsens went back to all cat fuel filters (took 2 sets) and never had that problem again.

My problems started after a year of running donaldsens and then got an oil chg, ran through 2 sets of filters in 1000 miles, changed em to cats and the problem just disappeared. I THINK its something to do with the micron size of cats being larger essentially allowing better fuel flow.

If you change oil at ta, they dont upcharge for cat filters anymore and usually stock them

 

Had Donaldson too, scrap, new cat filters installed after.

I noticed the fuel pressure gauge took 45 seconds to go from 0-80 psi while starting truck and engine running.

Cat filters immediately go to 80 at the press of a starter button

 

Fancy! Cat stuff always look good when the box is opened

 

True, but if you open your wallet at the same time, it doesnt look so hot lol