MazdaManiac

iTrader: (3)

The MAF tube on the STi is only 3". 'Nuff said.

Meh, I might disagree on that.
It is a safe generalization, but I have a few 215 HP N/A RX-8s running around out there.

In the range of .0003 sec. However, the air itself doesn't have to travel that distance so "slowly". It just bumps the molecules in front of it forward, so the air actually arrives at its destination somewhere over the speed of sound.

The OE PCM is more powerful than ANY aftermarket EMS out there. What AUX controls do you want? You can use unused AUX items in the OE setup (like the VFAD) to control stuff.

There are a HUGE number of things to play with. Its a bit like the AEM EMS. THe software not being out yet is probably a good thing, especially fro the FI crowd. There is a steep learning curve.
The Int-X is simple because it is a hammer. A good EMS should be a scalpel. The OE PCM is a laser.

mdw1000

I don't have any experience with the AP, but I do know that my car is quicker to respond to throttle input with the IntX now installed. Not sure how much of that is due to the tune and how much is due to the whole MAP vs MAF thing. I do remember reading in one of Jeff Hartman's books that MAP is generally more responsive than MAF. He didn't give a specific figure, so I don't know by how much. I would imagine it varies by application.

MazdaManiac

iTrader: (3)

Exactly the opposite.

And, no, Hartman didn't say anything of the sort.

If you think about how each works for a second, you will realize how absurd that assertion is. In fact, in some applications, a MAP is a better system because a MAF is too sensitive.

mdw1000

Sorry, hadn't checked this thread for a couple days.

Knowing that my memory has known to be wrong more than 1 billon times, I took a look at the book again to see what the heck I was talking about. I believe this is where I got the idea from. The book is "How to Tune and Modify Engine Management Systems" by Jeff Hartman.

On page 22 he says "MAF meters tend to be slow to respond to rapid changes in load (sudden wide-open throttle) and therefore require supplemental means of control to manage engines under rapidly changing conditions".

On the same page he says "Speed-density control systems respond quickly to changes in load".

However, I would imagine if the "supplemental means of control" he refers to are present, then it renders the comparison moot.

MazdaManiac

iTrader: (3)

Both require a throttle position sensor.
However, he is wrong about the MAF sensors being slow. I'm not sure where that quote is, but I'll take him to task on it when I find it.
MAFs will register if you sneeze on the air filter.

mdw1000

The copyright on the book is 2003. Have there been changes to MAF sensors in general since then?

The MAF quote is from the first sentence of the third full paragraph on the right side of page 22, at least in the version that I have.

MazdaManiac

iTrader: (3)

Well, obviously, Mr. Hartman was confused.
Look what he wrote on page 40 in the very first paragraph about MAFs.

This is why you must take this stuff with a grain of salt.

mdw1000

True, although he does say the MAF reacts "almost" instantly. Although I would think technically neither one could react truly instantly.

In either case I'm guessing the difference I feel in my car is due more to the tune than the type of sensor.

mysql

I haven't seen much difference in terms of reaction time between usage of the int-x vs ap. They both respond appropriately. The only noticeable thing is the poor idle characteristics of the int-x, but I'm not sure if that's a MAP thing or the way the int-x itself operates.

MazdaManiac

iTrader: (3)

Both.
MAF is instant. Air and fuel are not. That is the only delay in a MAF-based system.

shaunv74

Yes Velectrons>Vair or Vfuel. unfortunately not everything can move at the speed of light...

mdw1000

I've actually managed to mostly solve (knock on wood) the idle problems I was having. But I've only had it installed for a short time, so I don't know if time will reveal more of them. I do plan on putting the IAT sensor on, so that should help some, I would think. I bought it back before the AP was released, but only got to install it recently.

I do know that Scott said that the idle is easier to control on the AT (because of the constant load, I believe). However, my main idle problem was hot start idle when the car was in park or neutral. That problem was fixed by adjusting the TPS_Cal function.

The car has definitely picked up some power and responsiveness as opposed to stock with the Mazsport base map.

mysql

My idle was mostly OK with the int-x, but it had issues when it was hot out and using the mazsport cooling fan mod at the same time. Idle suffered and the car sometimes stalled. Scott was not able to correct it so I ended up inducing a vacuum leak on the top of the intake manifold. This lessened the problem. Eventually I tired of doing that I simply unplugged one of the fuses during summer (when it would have been more useful plugged in). With only one fan on high setting, the car stopped stalling.

Even if your idle seems ok and you don't stall, the idle isn't necessarily great as you tend to end up with an idle in the 11-12 AFR range. Stock setup will idle around 15.

mdw1000

So far no problems with the cooling mod/Intx combo.

I've got a WBO2 on the way (and the temp sensor), so I'll know more about the AFRs in the near future. Thanks for the tip - I'll be sure to check out the idle AFRs.

mysql

JFYI the coolint/int-x issue was reported by many members. Not just me. That's how I got the vacuum leak temp fix, from someone else who had the same problem.

mdw1000

Yeah, I remember reading about people having trouble with the IntX and the cooling mod causing idle issues. I was just saying that so far I'm not one of them (knock on wood).

You mention you had the problem when it was hot? I assume you are referring to ambient temps. I lived in FL for a few months many years ago, and your ambient temps are definitely hotter down there than ours are up here. We only get a few days generally of what you guys have all summer long.

Did you have the IAT sensor installed on your IntX? I don't have mine installed yet, but I will be putting one on soon. I'm hoping that helps alleviate some of the temperature related issues some have reported.