Thanks, Bill - makes perfect sense to me. And, I can see how your A/F curves smoothly adopt that strategy, rather than having the sharp "bump" at 4500 rpm.

But, now I've started "thinking" again (which I know is dangerous). The stock curve seems to hold the A/F ratio near 14.08 (the ideal for E10). And, I have to imagine the older trucks like my 2005 and earlier tried to hold it at 14.64 (for REAL gas ;) ), so did Ford put out a flash to the PCM to "adapt" them to E10 when it sort of became the "standard"? As I recall from the f150 forums, the 2004-2005s were already lean running when they came out. E10 would just make things worse, right?

- Jack

To some degree. Keep in mind that the vehicle tested was a FlexFuel vehicle and had the ethanol sensor. Also, don't forget that those are WOT runs. The fuel strategies are a little bit different at WOT than at cruise where 15+ AFR is not uncommon.

That is pretty Fricken sweet.nice job.

Really? I thought this was a recipe for disaster. I always heard how leaning a motor out could wreck any number of parts, most notably the pistons. is there any truth to this? is it only under certain conditions?

At cruise, there's very little load on the engine. I imagine that's how you get away with a lean A/F setting.

- Jack

Exactly. Running a tad lean (lean being a relative term here) during light cruise (minimum load) is not uncommon for most auto manufacturers. In fact, I've seen as high as 15.8:1 under light cruise. Under acceleration or load, fuel curves will richen up as necessary to keep things safe.

Ok, so it's Lean + Load conditions that can cause issues.
thanks for the clarification!

Couldn't have said it better myself! :2thumbs:

Bill,
I do not have a Gryphon yet, hopefully soon...that being said, because of the air intake mod I have, do you think it would be detrimental to my engine (stock 5.4 3v with stock air filter) to make WOT runs? Should I cap off the ram air section and just let it breathe through the fenderwell until I get a Gryphon?
I haven't made any WOT runs yet, and based upon your explanation of A/F ratios it's probably a good thing I haven't.
Thanks for any guidance.

Let's see if I can get this right before Bill chimes in: :)

I think, because you've done no modifications to the intake system past the intake tube (the filter box and filter are all stock), you're not going to fool the MAF sensor into thinking there's less airflow than there really is. So, I don't think you have to worry about running lean.

But - and here I don't really have a clue how to proceed - at high speeds, your "ram" air intake is going to have a little bit of the effect of a blower (although I doubt it will be TOO significant). That COULD upset things a bit.

(BTW - the only reason I jumped in here was to test my understanding of this concern).

- Jack