Direct Injection AFR....

[JQmile]

I have a 2016 Mustang Ecoboost that I've been messing with, and I have the rare opportunity to work directly with the tuner writing the programs. So far the performance side has been good, but I'm thinking a mileage tune would be sweet as well. The car gets about 33 mpg at 70 mph, at a 14:1 air/fuel ratio, whaddya guys think of bumping that up a bit? Only thing I could find is that one guy said he was running 14.5-15:1 and that you have to worry about CAT temps.

Advice/opinions?

[gone-ot]

Yes, worry about the catalytic temperatures...especially in CARB-land!

[teoman]

Too high or too low?

[Ecky]

I'm under the impression that leaner is better, until it starts stumbling.

[teoman]

I meant the CAT temp.

You can insulate it or add cooling fins to the exhaust (or water steam injection)

[ar5boosted]

Yeah go for it and share the results.

An ecomod tune shouldn't overheat the cat if you are doing pulse-and-glide type driving. All modern EFI systems inject more fuel so that the fuel burns in the cat and the whole exhaust system runs hotter in modern cars.

Just think.. what can go wrong...?

and start thinking up an excuse early to tell her.

[Baltothewolf]

Or, just fabricate a pipe to swap out for the cat so you don't have to worry about it, and when you gotta smog swap it back.

[cRiPpLe_rOoStEr]

Just to remind that a leaner AFR usually leads to a higher EGT. BTW can you eventually mess with the VVT to make it go "Atkinson-capable" like that Toyota 8AR-FTS engine currently fitted to some Lexus models?

Originally Posted by Baltothewolf

Or, just fabricate a pipe to swap out for the cat so you don't have to worry about it, and when you gotta smog swap it back.

Probably would need to revert to stock tune in order to get approved on the smog test anyways.

[rmay635703]

Changing the fuel injection timing in DI can enable AFRs far leaner without much stumble (striated burn)