Cat vs Cummins: I ran both injector setups back to back on the same 3406E

Ngl I spent 8 months running Cat injectors in my 3406E and swapped to Cummins CELEA injectors last Tuesday. The Cat ones just don't hold up past 300k miles without losing pressure. After the swap I gained 2 MPG on my Pete hauling logs out of Eugene. The CELEA injectors also cut my idle smoke by half. Has anyone else tested this swap on a 3406E without changing the ECM calibration?

2 comments

2 Comments

felix3857d agoProlific Poster

My buddy Dave ran that same swap on his 3406E in his ’97 W900 about two years back. He didn’t change the ECM calibration either, and he actually had to bump the fuel pressure up a little to get the smoke down where he wanted it. He said the Cats felt smoother at idle but the Cummins injectors pulled harder on a grade, especially when he was hauling out of the coast range.

felix3856d agoProlific Poster

That bump in fuel pressure was probly the trick, I've heard a few guys say the same thing about needing a little more fuel to clean up the dump on those swaps. The smoother idle on the Cats makes sense since they're four-valve heads and fire a little different. But that pulling power on a grade is where it really counts, especially with a heavy load out of the coast range where you're fighting elevation and curves at the same time. Dave's setup sounds like it walks the line pretty good between drivability and grunt. You get any heat soak issues when he's really working it hard?