Aeroforce Interceptor... does it read Manifold Pressure??? - JKowners.com : Jeep Wrangler JK Forum
 
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post #1 of 9 Old 03-22-2017, 09:58 PM Thread Starter
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Aeroforce Interceptor... does it read Manifold Pressure???

Anyone out there who has an Aeroforce on a 2015+ JK...

Does it read "Manifold Pressure (vacuum/boost) displayed in psi" ..?

Its on the list of parameters possible on the gauge, but not sure if this is available on the JK... if it is I don't need to worry about setting up the analog input to the aeroforce to read boost from the 2 bar MAP on the supercharger that is in my near future...

(if it does read out on the OBD-II, you will see a -ve number I think, for naturally aspirated, as it will be vacuum... guessing maybe -10psi at idle..? When you squirt the gas you should see it move)

Cheers,
S.

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post #2 of 9 Old 03-23-2017, 02:57 PM Thread Starter
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Got my answer direct from Todd @ Aeroforce... for anyone searching in the future, details are below:


A1Fc- Jeep Wrangler Supported Parameters (PID’S) – CNCjk version

1. INTAKE AIR- Intake Air Temperature
2. AMBIENT AIR TEMPERATURE
3. COOLANT TEMP- Engine Coolant Temperature
5. CAT TEMP B1S1 – calculated exhaust temp at primary passenger side cat converter
6. CAT TEMP B2S1 – calculated exhaust temp at primary driver side cat converter
4. RPM- engine Revolutions Per Minute
5. BOOST/VACUUM
6. MAP kPa – absolute manifold pressure in kPa
7. MPH
8. THROTTLE %
9. IGNITION ADV.-
10. STFT 1 – Short term fuel trim bank 1
11. STFT 2 – bank 2
12. LTFT 1 – Long term fuel trim bank 1
13. LTFT 2 – bank 2
14. O2 MV 1 – mv output of sensor 1
15. O2 MV 3 – mv output or sensor 2 (Chrysler designates this as O2 parameter 3)
16. ENGINE LOAD
17. FUEL STAT – Open or Closed (CL) loop fueling
18. RUN TIME – in tenths of a minute. Resets when engine is turned off
19. CMD A/F – PCM commanded Air/Fuel ratio
20. BAROMETER
21. BATTERY VOLTAGE
23. STEERING ANGLE – Steering wheel angle
24. YAW – from body accelerometers
25. BRAKE PSI – Brake line pressure
26. LATERAL G – Lateral acceleration
25. TCC SLIP – Torque converter slip 2012 and newer MY
26. TCC STATE – Torque converter mode (1= unlocked, 2 = partial, 3 = locked) 2012 and newer MY
27. GEAR – current transmission gear (auto) 2012 and newer MY
28. TRANS TEMP – transmission temp (auto) 2012 and newer MY
29. TORQUE – PCM calculated torque (auto) 2012 and newer MY
30. OUTPUT SHAFT – engine output shaft speed (auto) 2012 and newer MY
27. Analog 1 – analog input #1
28. Analog 2
29. MAF LB/MIN – PCM calculated mass air flow
30. MPG – fuel economy
31. HP – Calculated horsepower
32. FUEL LEFT
32. ST KR – knock retard
35. PW – Injector #1 pulse width
36. INJ DC – Injector duty cycle
37. OIL PRESSURE – 2012 and newer only
37. TCC SLIP 07-11 – torque converter slip (auto trans) for 2007-2011 MY
38. TRANS T 07-11 – transmission temperature (auto trans) for 2007-2011 MY
39. TR CASE – Transfer case status
40. TIRE SIZE – Circumference in millimeters
41. OIL TEMP – oil temperature 2012 and newer only
42. SUMMARY: displays current values for tire size, axle ratio, and transfer case ratios.

It will read boost from the MAP sensor, so if it's replaced with a 2 bar or higher MAP you'll be able to read positive boost.

You can also program new tire sizes, turn off ESP, program axle ratio, program transfer case ratio, turn off sway bar light, raise idle speed, change the TPMS warning threshold.

Todd
Aeroforce

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post #3 of 9 Old 03-23-2017, 08:17 PM
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Make sure that the gauge can show you "SPK RETARD LT" in addition to ST. Long term retard indicates a more severe condition. It is generally okay to have some short term retard (PCM pulls a little timing) but having any long term is generally considered bad.

A 1BAR MAP sensor will also read boost. It just has a narrower range than a 2BAR or a 3BAR.

The MAP signal alone is not very useful as boost is really MAP minus the barometric pressure.

If you get a supercharger that includes a tuner like the Diablosport Trinity, you safely skip that gauge altogether. The Trinity will give you true boost, which is a calculated number (MAP-BARO). And even then you will only see positive boost in PSI or KPA, no vacuum. If you want vacuum then you need a vacuum/boost gauge.
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post #4 of 9 Old 03-24-2017, 01:33 AM Thread Starter
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A MAP measures absolute pressure (Manifold Absolute Pressure), not gauge pressure (which is relative to atmosphere), which means from absolute vacuum up to whatever the MAP's limit is... for a 1 bar sensor, that means absolute vacuum up to atmospheric (or approx 1 bar, which is 14.7psi)... so it will not measure boost, its limit is basically atmospheric pressure (zero psi boost). A naturally aspirated engine will always run at vacuum in the manifold, which is why many use a 1 bar sensor. For a 2 bar MAP, that means absolute vacuum up to 2 bar, or 29.4 psi, which is 14.7 psi of boost.

To convert absolute pressure to boost, or vacuum, yes - you have to subtract atmospheric pressure. So if the MAP is reading 29.4psi, that is actually 14.7psi of boost. So with a 2 or 3 bar MAP, you can measure 14.7 or 29.4psi of boost respectively. Given the boost on these SC's is 7 or 8psi, the 2 bar will easily cover it.

The Aeroforce in analog input allows you to set the slope & offset/intercept, so it will read in vacuum and boost from a 2 bar MAP. What I was interested in was whether it would do the same reading via the OBD port, given the engine management needs this info anyway, and the supercharger kit includes a 2 bar MAP which replaces the standard 1 bar MAP. From the reply below, looks like you can have both... the absolute measure (measured from absolute vacuum, in kPa), AND the vacuum/boost measure (which is corrected for atmospheric pressure).

You don't need a vacuum/boost gauge, you can get the info from the MAP and correct it.

So... a 2 bar MAP will give you vacuum & boost, by correcting the absolute pressure using the atmospheric/barometric pressure... and it seems the Aeroforce will display it. Happy days!

(if it didn't display via the OBD port, then you can always hook up the analog and add the slope & intercept, and then it will give you vacuum & boost from a 2 bar MAP)

Sorry the above turned out a bit tough to follow, hopefully it makes some sense. Another complication is the atmospheric pressure changes with altitude and even the weather, so the analog calibration you put in (the intercept specifically) will change, particularly at high altitude.

Cheers,
S.

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post #5 of 9 Old 03-24-2017, 09:36 AM
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Quote:
Originally Posted by FireTruck View Post
A MAP measures absolute pressure (Manifold Absolute Pressure), not gauge pressure (which is relative to atmosphere), which means from absolute vacuum up to whatever the MAP's limit is... for a 1 bar sensor, that means absolute vacuum up to atmospheric (or approx 1 bar, which is 14.7psi)... so it will not measure boost, its limit is basically atmospheric pressure (zero psi boost). A naturally aspirated engine will always run at vacuum in the manifold, which is why many use a 1 bar sensor. For a 2 bar MAP, that means absolute vacuum up to 2 bar, or 29.4 psi, which is 14.7 psi of boost.

To convert absolute pressure to boost, or vacuum, yes - you have to subtract atmospheric pressure. So if the MAP is reading 29.4psi, that is actually 14.7psi of boost. So with a 2 or 3 bar MAP, you can measure 14.7 or 29.4psi of boost respectively. Given the boost on these SC's is 7 or 8psi, the 2 bar will easily cover it.

The Aeroforce in analog input allows you to set the slope & offset/intercept, so it will read in vacuum and boost from a 2 bar MAP. What I was interested in was whether it would do the same reading via the OBD port, given the engine management needs this info anyway, and the supercharger kit includes a 2 bar MAP which replaces the standard 1 bar MAP. From the reply below, looks like you can have both... the absolute measure (measured from absolute vacuum, in kPa), AND the vacuum/boost measure (which is corrected for atmospheric pressure).

You don't need a vacuum/boost gauge, you can get the info from the MAP and correct it.

So... a 2 bar MAP will give you vacuum & boost, by correcting the absolute pressure using the atmospheric/barometric pressure... and it seems the Aeroforce will display it. Happy days!

(if it didn't display via the OBD port, then you can always hook up the analog and add the slope & intercept, and then it will give you vacuum & boost from a 2 bar MAP)

Sorry the above turned out a bit tough to follow, hopefully it makes some sense. Another complication is the atmospheric pressure changes with altitude and even the weather, so the analog calibration you put in (the intercept specifically) will change, particularly at high altitude.

Cheers,
S.
Hey man, thanks for the schooling on MAP sensors. MAP sensors have actually been around since the old carburetor days when they were basically just on off switches that tripped at a particular altitude. Old carbureted cars would use them while in closed loop. But who cares.

It’s apparent that you misunderstand how MAP sensors actually work. First of all, they are fed a fixed +5vdc signal and a good ground. There is usually one output wire and this will range from 0 to +5vdc. The output does not convert 0 to 14.5psi, it is centered. Rather, it is -7.25psi to +7.25psi PSI. The -7.25psi can be converted to inches of mercury by multiplying the number by 2.03602. So a 1BAR MAP sensor would have a range of say 14.76Hg to 7.25psi. Similarly, a 2BAR MAP sensor would measure the range of 29.52Hg to 14.5psi. Though not practical for any significant amount of boost, the 1BAR MAP sensor does indeed measure positive boost.

Electronic boost gauges (that I am familiar with) are based on 2 and 3 BAR MAP sensors. I chose one based on a 2BAR to match the 2BAR Mopar MAP sensor that came with the blower kit. When I compare the output between my electronic boost gauge and the trinity they are within 0.20psi of each other and that is saying a lot because we are talking about two discrete MAP sensors and circuits. And the MAP sensor that came with the gauge appears to be a GM or some other brand.

The Trinity has a soft “boost” gauge built in, under the “synthesized” PIDs section. You can just add that to your gauge panel page. Even so, it will only read positive boost in the calculation. I wanted to read vacuum as well so I had to go to a real gauge. I am not sure any of the tuning devices or the aeroforce gauge can actually display both. It is being measured either way and fed to the PCM in terms of a 0-+5vdc signal.

The boost gauge does not calculate the boost real time like the above solutions do. It references barometric pressure when you first turn the key on and sets the zero point there. Because of this, you have to be careful to wire the gauge to a circuit that is switched on with the key but not interrupted during cranking/starting as most circuits are (except ignition and fuel, as examples). Interestingly, I think there is a situation where the gauge can become temporarily inaccurate. I live right at about sea level and live life under ~500’. I have to drive 3 hours to the mountains (~7,500’) to go wheeling. The gauge won’t recalibrate the zero point until I stop for gas before trail head or when I am airing down, right at trail head.

I looked at the aeroforce gauges at first too but ultimately passed on them. I would have needed two for my purpose plus a third gauge for the water methanol injection. Compared to a Trinity or any other touch screen type gauges, the touch screen gauges can have 4 or more gauges on a given screen page. That and the gauges can be just plain old digits like the interceptor or they can be anything else. More importantly, you can do data logging directly with devices like the Trinity and pull in the analog signal directly in for your tune-by-email guy. The aeroforce gauges can have multiple functions but you have to cycle through them. I have two analog inputs being pulled in. AFR and WMI flow. I can log it all easily or watch it all real time. To do what I needed with the aeroforce gauge would have required two gauges plus a tuning device anyway. Two aeroforce gauges come to about what you can get a single tuning device for that also has the same functions – and then some. One of my most used gauge panels consists of the following four gauges: KNK RETARD ST, KNK RETARD LT, AFR and IAT. Other handy gauge “panels” are a page (and a button click) away.

It sounds like the aeroforce is just giving you the raw MAP signal and calling that boost. You might was well just learn it in terms of the 0 to +5vdc output and just watch it with a simple volt meter. That is what the PCM is doing.
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post #6 of 9 Old 03-25-2017, 09:52 AM Thread Starter
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I guess you learn something new everyday... Haven't been able to find any references of a MAP measuring from above absolute vacuum (ie the +/- C entered you mention around atmosphere)... But when I was searching for a reference showing that I found a lot of stuff on MAPs measuring from absolute vacuum up...

Eg. https://splitsec.com/wp-content/uplo...Map_Sensor.pdf

I do understand that pretty much all the sensor run a 5v input, as a stable reference voltage, to isolate the reference from fluctuations that you would otherwise get from the 12v... Which is all over the place. And yes, the aeroforce converts the 0-5v signal to psi (using the slope and intercept... A simple straight line equation, y=mx+c). The 2 bar map covers from absolute vacuum (close to zero volts), to atmosphere or zero boost (around 2.5v), and up to 2 atmospheres or 14.7psi boost (around 5v)... As far as I can tell from the feedback and research so far.

I also wondered if the JK MAP takes the barometric pressure snapshot at startup or after engine off - I know different vehicles handle it in different ways. I think you are saying it takes the baseline at startup, right? Good to know.

Anyway, appreciate all the tech, now the fun begins...

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post #7 of 9 Old 03-25-2017, 08:20 PM Thread Starter
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Mate, still struggling to find any info on MAP sensors (1 bar) reading vacuum and boost centred around barometric/atmospheric. They are designed to measure up from absolute vacuum, zero pressure, so without the aid of a gauge offset calibration, I'm struggling to find any info on this...

But more and more on absolute from vacuum:

http://www.airtexve.com/ds_map.html

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post #8 of 9 Old 03-28-2017, 12:07 PM
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Hey man.... I could not find anything either.

If I get my lazy self up into the attic, I will snatch the stock 1BAR sensor out of my stock intake manifold and conduct a little test.

What I hope to prove on a bench test is that a 1BAR MAO sensor will register even a small amount of boost. AN interesting reference point will be what the output voltage is while just sitting there with the key on and the motor not running. At sea level with no vacuum or boost, we should see something close to but not quite +5vdc.

Then again, if I have to eat crow, it might go well with a garlic, thyme & butter sauce. One might also have to drink a crap ton of Toohey's (not Fosters, the export swill) before choking the crow down.
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post #9 of 9 Old 03-28-2017, 04:15 PM Thread Starter
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The bench test would do it, probably expect 4.6 ish volts...

But no need to drag it out for me - I'll just slap a 2 bar in regardless, as that will surely have the range (either way).

I'm a fan of BBQ crow myself, but prefer a nice hoppy IPA to wash it down... I'm on the process of moving to the US from Aus, and I have to say I'm pretty impressed with the array of craft micro brews here these days... Will make the landing nice and soft :-)

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