wiring second map sensor for barometric correction

[ethergore]

Hello everyone. I wanted to start off by explaining that I am a complete novice with ecu install/tuning. I'm running an ITBd 16 valve 4ag on straight map. It was installed and street tuned by a buddy who can no longer help me.

Car runs great at my current altitude but even a short climb prevents the map from getting to 101 kpa causing lean conditions.

I was wondering if someone could give me some easy instructions on wiring and setting up a second map sensor? I picked a sensor from the junk yard off a Honda that needs a 5 volt source.

I'm guessing I can use pin 28 that is not in use to get a 5 volt source. I have analog channel 7 available for the input signal.  Would this be the right way to go and do I ground to ecu or to chassis?

Again sorry if I am way off but I am a complete newb but could really use some help.

Thanks!

[gunni]

Where is your map sensor placed? As it will see variance in pressure based on atmospheric pressure, also have a look in

"Base Setup" - "Engine Setup" . There you can see Barometric pressure correction, is that on or off?
If it´s ON what settings does it have?

[ethergore]

my current map sensor is routed into a vacuum block connected to my itbs.

My baro correction is turned off.

[ethergore]

So I went ahead and wired in the sensor.  Ground went to sensor ground, got 5 volt from pin 28 and signal is going in to analog input 7.

I have a reading into the ecu and tried seeing up the barometric correction but it doesn't seem to be doing anything.

[Grant]

Hi Guys,

I'm Ethergore's friend/installer.  I've been on the board a few times for my own AE86 in the past.  I work very closely with SlyAlfa, one of the board developers.  I'm currently working with him to develop a plug and play AE86 and VEMS solution for the community.

I asked Ethergore to ask about this here as I have not had to add external Baro on my own installs and am not familiar with it.  I would direct him to go here but the images seem to be broken...

http://www.vems.hu/wiki/?page=MembersPage/PhatBob/UserGuide

Ehtergore, if you haven't already, I'd look for the VEMS manual on this forum, otherwise, that's the guide I used.

hope Gunni and others can help out more!

Grant

[ethergore]

I read the manual on that link, as well as, the newer manual by Jason Russell and there is nothing about seeing up the second map sensor for baro  correction.  Is there another manual I'm not finding?

[VEMS]

Hello Ethergore,

See: http://vems.hu/vt/help/v3/v3_engine_setup.html

Connect the sensor to a free analog input _without pull-up_ (the paper supplied with your ecu shows you where), then select Dynamic mode, select your used analog input channel and sensor calibration values and done.

Best regards, Dave

[ethergore]

Maybe I selected an analog channel with a pull up. I don't have the documentation that came with the vems as it was installed by someone else.  When I look at the voltage it is sitting at 5 volts so maybe it's not correct due to the pull up.

I don't know if I calibrated correctly either.  I used the wizard and entered 0 volts and 5 volts corresponding to 10 kpa and 105 kpa and burned those to the input channel.

I'm guessing I can set the voltage higher on the calibration wizard and if I get a reading above 5 volts I'll know I'm on a channel with a pull up.

[VEMS]

Then perhaps its best if you consult the person why did the setup and install of the system, you seems to be having wiring and configuration issues. For now i would advice to keep barometric correction disabled until there have been diagnosed.

Best regards, Dave

[Grant]

Hi,

I did the wiring and install.  Car works great but we had no provision for 2nd Baro as I've never needed it. Ethergore lives in an area with large altitude changes, which we found out after transporting the car to him (6 hours away). 

What issue did you see with how the Baro was responding that made you suspect wiring issue?

Grant

[Grant]

Also Dave, Ehtergore's VEMS is not a full production unit.  It was sent to one of the HW developers for VEMS for use on this project, hence no supplied documentation.  I believe it's a V3.6 if I recall.

Ethergore, you may want to post which firmware version you are using as well.  It should be noted we could only get the car to run without trigger errors with a particular firmware for some reason.

Grant

[ethergore]

I'm guessing the sensor may be going to a channel with a pull up because it was pegged at a 5 volt signal. When I get home ill calibrate it to a higher voltage and see if I get a reading above 5 volts.  If I do that should suggest I'm on a pull up right?

I'm guessing the barometer correction was doing nothing because it thinks it's at 100 kpa already. The fix might be as easy as changing to another analog input.

Any flaws in my logic? I honestly don't really understand what a pull up resistor is other than what I just read on Wikipedia.

[ethergore]

 

Ethergore, you may want to post which firmware version you are using as well.  It should be noted we could only get the car to run without trigger errors with a particular firmware for some reason.

I'll post the firmware version when I get home.

[ethergore]

So I forgot to post my firmware when I got home yesterday but I did some more testing to try and get things working.

I figured out how to view all of my analog inputs to see what kind of data I'm getting.  I unplugged my serving map sensor and saw I was still getting a 5 volt signal. I observed that there was data going in to all channels except 0, 1, 3 or 4. I tried channel 4 but still got no signal.  Map sensor already verified to be sending a signal.

Since I have a 3.6 ecu I'm using that pin out but it seems to have variations.  I need to some how figure out my specific pin outs.  Can I do this with a serial number or maybe even take a picture of the board or how do I proceed in finding an appropriate input pin?

[Grant]

Hi Guys, Ethergore sent the ECU back to us to look at.  It looks like SlyAlfa didn't setup an ADC wiring as there was no plan to use bro correction.

We have wired up a early 2000's Denso sensor on pin 16 which is tied to ADC channel 5.

The issue we are having is ADC is far too unstable.  Voltage at the sensor is verified stable ...around 3 volts.  But when viewing on VEMS tune, voltage fluctuates +/- .07 volts...this causes Baro input to rapidly fluctuate between 98-104 KpA, too unstable to be useful for us. 

Does anyone know why ADC is jumping around so much?  Is that normal?  We noticed ADC jumps around on all channels, not just the one we are testing on.  We feel that we can help Ethergore with external baro as soon as ADC issue is resolved.

**Please view short clip in link below**  =]

http://youtu.be/MBMO8Ek63Ko