Good to see some discussion on this topic.
Good to see some discussion on any topic ... these days
Get something to drink or a snack before starting on this one
This is the perfect time to point out that any kind of topic a 94-95 guy wants to do some exhaustive research on .......................
he has to endure 90% of Fox bs before he gets to data that pertains to his car
The Fox pcm operation is a good bit different than our pcm's.
I know for sure adaptive has a limit of adjustment
What I am unsure about is the difference between Fox & us as far as throwing the CEL
I do know on our cars, the CEL will be envoked at times if adaptive has reached its limit.
The explanation JT gave is the one you mostly see that is out there.
however
I have seen some say they are not so sure our pcm's work like that and I'm sure their suspicions are based on data they have gathered.
You have the ability to see realtime data which is great
but
there are times you have no reason for why you see ...... what you see
Examples
1) I have seen my final wot af ratio drift a small amount over a long preiod of time.
I have no answer for this
2) I have seen my final wot af ratio change with a difference in outside temps.
I reported this finding on the tuner forum and it caused all kinds of talk about why it could not happen cause the maf would compensate for temp changes and other various reasons.
Hey ... all the talk was interesting ... but ... I still had hard data showing what I said took place ... did in fact happen
My Closed Loop tune is pretty stable and the Adaptive Strategy does not make very big changes
but
it is impossible for ANYONE, even a Pro Tuner, to create a tune where the Adaptive makes NO changes over time.
Having said that ...... I suspect ... I repeat the word ... SUSPECT ... Open Loop does in fact get some input from Closed Loop Driving Conditions and the pcm makes some kind of change that does in fact ... effect Open Loop Driving Conditions.
A good bit of Fox stuff does not apply to our cars but it has been mistaken as fact for our cars as it IS fact for the Fox cars.
The setting of the tps comes to mind.
Some swear setting it helps ...... some say no it doesn't
The adjustment of fuel pressure is kinda in that camp I guess.
Here is a thing or two I do know for sure about the pcm and fuel pressure.
1) From everything I have seen, the pcm has no knowledge about fuel pressure.
2) The pressure value like the spark value is assumed by the pcm to be at stock value.
3) Hosing around with the pressure will most definitely effect the Closed Loop operation of the pcm and its Adaptive Strategy will try to negate that mechanical adjustment.
Now it is true that WOT driving conditions are in the Open Loop Strategy of the pcm
but
unless you got a way to tell the pcm you want to operate 100% of the time in Open Loop ... it don't make no difference anyway.
Having said that we come full circle in this discussion and are back to where we started.
I have this opinion on AFPR's and their use for 94-95 cars.
Ford designed the pcm and all its supporting sensors for stock pressure.
Even if running elevated pressures is effective for a fatter WOT ratio ...
those elevated pressures are gonna hose up drivability.
For Our Load Based PCM's ....................
the most accurate way to compensate for more airflow & fuel is to
Tell the pcm the truth about airflow & fuel
as opposed to
1) The cheat method after-market maf makers have devised
2) Mechanical adjustment of fuel pressure
Summing up and Final Thoughts here
Using Elevated Fuel Pressure is not without its draw backs
so .........................
even though I don't understand everything about what is really going on with this topic ...............
Those known draw backs are enough to tell me ...
AFPR's
may HURT more than they HELP
Grady