Heres a thought on passing emission test

[Jackpine]

Being able to clear the P1000 code after returning to stock would kind of negate the whole "learning strategy" thing Ford built into the PCM so that it would perform the way Ford wants (to pass emissions "exhaust gas sniffers").

But, I'm going to stick my neck out and "voice" what I think is the "obvious" point that Bill mentioned, since I think it's kind of subtle. If the P1000 code was set when loading a custom (or canned tune), the PCM would try to bring everything (emissions-wise) back to the stock tune, and it would do that in about 50 miles of driving, negating much of the custom tune.

There are several posters over on f150online who don't see this possibility and have said they don't think custom tunes are worth anything because of the drive cycle, relearn thing. I think Bill has just shown you how they are wrong.

And, I hadn't thought much about this until reading this thread. Thanks for educating an old dog, Bill!

- Jack

[Power Hungry]

One thing about drive cycles and relearn procedures is that they handle a relatively specific set of driving conditions... Mainly "closed loop" light to mid throttle fuel curves. Open loop fuel, timing curves, camshaft curves, shifting (points, not pressure), torque management and other functions are not controlled by the relearn procedures. Timing is controlled by knock sensors, but that's another story.

Much of the perceptible performance gains under hard acceleration come from timing curve and open loop fuel curve adjustments. Much of the fuel economy gains come from timing curve adjustments and changes to shifting strategies. At cruise, there is little fuel change outside of correcting for CAI discrepancies. This is why we can make more power and still be able to pass emissions test with ease. Modest timing curve adjustments can lead to reasonable improvements in fuel economy, but it also weighs heavily on fuel quality and octane. I have seen as much as a 2-3 MPG difference in fuel economy depending on which brand of gas I run or which station I fill up from. Performance difference is negligible though, at least for the old butt-dyno. The Expy always runs like a scalded dog.

Now... don't ya feel smarter?

[shotgun]

Yes I do. Everyday I lurk, I learn more good stuff.

Problem is I have limited HDD space so pretty soon I'm going to have to clean the old bionic hard drive...

[Longshot270]

Hehe, I was wondering where my last post was going to make this thread end up. Now I'm glad I did go out on a limb with a very basic question. I think we got some useful information for what would have been a deadly question on many of the other forums. I like having the "best case scenario" play out here, even when I had already suspected the answer.

Haha shotgun, I know what its like. If I clicked "submit" to every reply I almost made, I would probably have a thousand posts.

[88Racing]

Originally Posted by longshot270

Hehe, I was wondering where my last post was going to make this thread end up. Now I'm glad I did go out on a limb with a very basic question. I think we got some useful information for what would have been a deadly question on many of the other forums. I like having the "best case scenario" play out here, even when I had already suspected the answer.

Haha shotgun, I know what its like. If I clicked "submit" to every reply I almost made, I would probably have a thousand posts.

That definately would have been a "Fresh Meat" post in some of the other forums.
But in some of the other forums and their mile long threads it's hard to learn and utilize anything due to the thread crappers and other BS antics that goes on in them.
Good thing we are NICE around here!

[Longshot270]

Originally Posted by 88Racing

That definately would have been a "Fresh Meat" post in some of the other forums.
But in some of the other forums and their mile long threads it's hard to learn and utilize anything due to the thread crappers and other BS antics that goes on in them.
Good thing we are NICE around here!

...and intelligent, thats the biggie!
Hehe, yeah I figured that a "Fresh Meat" post would lure the Mintaur out while we all get to feast on some juicy information.

^....hey, sounds lame now but I guarantee it seemed pretty good when I typed it the first time.

Any other secrets about the tunes in reguards to drive cycles and emission?
(...or like which button combination to push to make jet engines come up and light for some extra passing power?)

[88Racing]

Originally Posted by longshot270

...and intelligent, thats the biggie!
Hehe, yeah I figured that a "Fresh Meat" post would lure the Mintaur out while we all get to feast on some juicy information.

^....hey, sounds lame now but I guarantee it seemed pretty good when I typed it the first time.

Any other secrets about the tunes in reguards to drive cycles and emission?
(...or like which button combination to push to make jet engines come up and light for some extra passing power?)

Looks like your truck!

http://m.youtube.com/index?desktop_u...ient=mv-google

you asked and you shall receive!

[Jackpine]

Back to another question for the Mad Doc, (if he sees this).

Since timing can be "corrected" (I won't use the term "controlled", because that's not how I see things working) by the knock sensors, what is the danger in overadvancing the timing? I get the feeling it's not a "cure-all" for sloppy timing adjustment. But, why not?

- Jack

[Power Hungry]

The reason it's best to use the knock sensor as an "emergency relief valve", so to speak, is that when the knock sensors detects detonation the PCM pulls out a HUGE amount of timing in one shot to protect the engine. This will have a significant impact on performance and economy. It is much better to go with a slightly less aggressive curve that doesn't cause detonation than it is to push the limits.

One other thing to consider is that some of the earlier engines DON'T have a knock sensor to compensate for sloppy timing curves. Obviously, things can go wrong quite quickly in this type of situation.