Boost is the opposite of vaccum and AFAIK we don't have a MAP, we have a MAF.

... and a MAP sensor will read both... in absolute pressure which can easily be converted to inHg for vacuum and psi for boost.

hmmm so vaccum/boost is only a unit or polarity difference?

I was wondering if you get positive pressure in the intake manifold...what happens to all the vacuum driven applications? (brake, some solenoid valves, etc..)

There are one way valves I believe that prevent that.

Ya that trap vacuum in the vacuum accumulator

+1 on the we do not have a map sensor

OK thanks! Sorry for my thread jacking noob question. Now we can get back to how Torque gets Vacuum and Boost without a MAP..

It's not "Torque" that gets vacuum. Torque is just reading the vacuum information that the ECU is sending...

A better question would be "where is the ECU getting vacuum from".

The weird thing is that if you change the engine size, it changes what the vacuum guage displays on the screen. Having the displacement at 2.6, and it seems to do pretty well. It does creep into positive pressure a little, 1-2 psi at high rpm. I was messing around with it the other day, and put the displacement to 3.9, and it wouldn't go above 11in vacuum. Just for fun, I put it to 1.3. I got to 10 PSI boost at very low throttle. Haha!

So I'm wondering how close the 2.6 engine size is, and if we actually do get positive pressure in the intake manifold at times. I know Mazda designed the intake tract to have pulse tuning....

Sounds to me like the torque app is broken.
Surely if the ecu was able to poll a vacuum sensor that Cobb would have also accessed that information as well for the AP.

Where's oltmann to dive into the ecu for us and let us know.

I gotta learn how he does that shit.

Edit
And in all my years hanging around this place and taking Jeff's webinars I've never once heard anything about an OEM vacuum sensor. Just saying.

Maybe the Torque app is reading the wrong PID.
Or maybe its creating a virtual vacuum by using several different values ... like the engine displacement and the RPM alone with the G/S value? <shrug>

In the end ... sounds broken, I'll continue to trust my Cobb AP over this solution.

Yeah, that's what I was thinking. Using MAF, throttle and some other things. It's like the VE there too. Obviously it can't know how much, it just calculates on guesses.

Mazmart Shopping Cart

Mazmart is selling used Boost/MAP sensor! How is that?

Edit: Corrected MAF to MAP...not sure why I typed MAF..

LoL That's barometric.

I was thinking geriatric ;)

In all seriousness... I'm actually a little confused... Imagine that! But I get your point now, Beodude!!! I just had to look at the actual link.

http://mazmart.com/ItemImages/T2_J3%...t%20Sensor.jpg

That is indeed the barometric sensor!

Yea I meant Boost/MAP. Is that not the thing we are talking about?

It's slightly mislabeled. That is basically a barometer. It is used to measure the ambient barometric pressure which is then used on a number of different tables for adjusting air/fuel ratios.

It is NOT a MAP. A MAP reports irrespective of atmospheric pressure and is plugged into your intake manifold. That sensor is open to atmosphere.

Ah OK learned something. So it should called atmosphere air pressure sensor. (AAP?) :P

Where is this guy in the engine bay? Just curious...I figure I will take a look

On the bracket for the air pump, passenger side of the engine bay, near the washer fluid bottle.

Cool thanks!

I have an issue with torque, the free version to just see how it works for now.

I tried putting in the PID,s listed in this thread but I get an error for an invalid equation, it doesnt seem to like the equations for STFT, LTFT, and cat temp. I'm guessing its just an issue with the free version but wanted to check before I paid for the app.

The STFT and LTFT work on the payed version. Just pay the $5.

Yes, the paid version is well worth the money. After the money spent on the phone/tablet and the adapter, $5 is peanuts to make full use of everything. The license is attached to your google account, so you can share it between devices if you have more than 1. I even bought a 2nd license for my wife, just so she could pull data if she ran into a problem without me there.

Good. Thats what I thought, but wanted to make sure. Its a great app.

If you think the free is good, wait till you get the paid one. If the free one is like taking a fun on-ramp, then the paid one is like a full track day at the Nurburgring. I had to use the free one temporarily a month or so ago, and felt massively handicapped. SOOO much more you can do with the paid. Make graphs, run more logs, faster response, plug ins, actual menu to use, code interface is far cleaner and allows for way more information (freeze frame, code lookup), mapping links, more PIDs already set to watch for (more than any 1 car will have), more gauge types, etc...

Hi
Can any one give me some help on how to get the Torque app to display air fuel ratio.
I see there is some equations on page one. but I have no idea what they mean.
Is there any instructions on how to do this in language that non tech savy people like me will understand?

The current version of torque will read AFR's just fine. Add Display -> Air Fuel Ratio (Measured)