14 Mack, 4.6 mpg? Can I get better mileage with it?

Sounds like a hack tune.

 

Hm, fair enough, I'm stuck with the thing though so I have to figure out a fix, not sure how a delete would cost me that much fuel economy. Honestly I'd still choose a delete over another 1 mpg, I was driving a rental about a week ago that decided it was going to stop pumping def, cost me a 14 per mile load. But anyways, I guess I'll add a tune up to the list, after the overhead. Just have to track down a good shop that does that sort of thing.

And I'll have to get back to you on the boost psi, I just know that it never goes past 30 for any reason.

 

It's not the delete that's causing it. Once it's deleted, there has to be a new tune/programming written for the ECM, otherwise the truck will go straight into limp mode, because the computer is like "WTF happened to my DEF sensors and my exhaust back pressure sensors, etc?"

So I mean you don't need a "tune up". You need a new tune uploaded to your ECM, or a new ECM with a reputable tune already on it.

 

Interesting, can you point me in the right direction for something like that then? Up until this point I've been driving by the books, trying to find info on shops that can fix a bad delete is hard when you don't know anyone. The only owner op I talk to just runs a pre eld truck.

 

Ask the person you bought the truck from. Not many people are going to refer anyone with work like this anymore. The Feds have gone full on Totalitarianism with it now. The EPA is the new KGB.

 

Well it was answered, I didn't get a chance. the problem is you need someone who can understand how to fix it, and that's going to be something that I don't think can be answered on this specific site.

Macks are good, but when there are hacks to the ecm firmware, you have issues that sometimes the only solution is to return the truck back to full compliance and deal with the emissions as everyone else. Your issue isn't unique, I've see it before with a couple delete trucks that came into the fleet and these were refitted with new emissions equipment, the dealer we work with made sure the ecm was up to date and the trucks returned a solid 7 loaded.

 

I don't know who could help you that's reputable. If I were you, I'd get on Google and start following rabbit holes. Someone here might also chime in if they know anyone.

You could ask on rawze.com. They handle these kinds of questions for the ISX, so they might know someone as well if they all hang in the same circles.

Also, this might not even be the problem. But flashing an ECM is cheap and quick, so it's worth a shot.

 

The dealer we work with on both the Macks and Western Stars said they won't touch a deleted truck or one that has the ecm replaced with something other than the right one. The shop manager said the EPA will shut them down if they don't have the policy.

 

Yeah, the dealer I got it from sells alot of deleted trucks, the only guy he referred me to about the def alert popping up said he can't help with my specific truck. Anytime I look up ECM tuning places they seem sketchy as hell.

I'm sure there is something up with it anyways considering it still gives me the def fault error when I start it up. It really seems like all they did was destroy the physical parts and do nothing to the computer. I'm assuming a proper ecm tune won't be throwing those codes at me.

 

The only reliable and legal solution to his problem.
It'll cost him, though.