Dedicated Baro sensor for '808

[Steve M]

Hi,
I'd like to use a second MAP sensor for the purpose of barometric update on my '808.

I can see that OSE V112 lists the capability for this but I would like more information on how to wire it in and set up the function in Tuner Pro.
My hadrware:
808 Ecu + NVRAM + USB Comms board.

Thanks in advance for any assistance.

[antus]

I have not done this, but I believe you would hook its signal pin to B12 as documented in the 12P pinouts and set the flag "Baro - Use 2nd MAP sensor input for Baro Correction"

[Steve M]

Thanks.
I saw those two details but was hoping to know whether to use the same 5V reference and sensor earths as the first MAP.
Can you see a problem with tapping into the MAP/TPS reference line and sharing existing earths?

I want to do this because my car really suffers from MAP readings when driving through the Adelaide hills. It leans out badly on the way up but has no issues on the flats.
Low rev/ high throttle does update the Baro and improve the situation, but that needs to be done multiple times on the ascent.

Cheers.

[vlad01]

I had a similar issue on Mt Macedon. Baro got updated on the way up easily as I was giving it a bit around the turns but got stuck behind a slow car on the way down
so the baro was still set at 85-90kpa and as I descend it got richer to the point I got a check engine light for the o2 being out of range in the rich direction.

A dedicated map would of helped.

[antus]

Hmm its an interesting one though. I live in Adelaide and have not had these problems driving around the Adelaide Hills - plains to Norton Summet and back. I understand it can be a problem for very large altitude changes but I dont think our Hills are the same scale as an actual mountain. You can install the second MAP using the same power and ground which the existing MAP already shares with TPS and see how you go, but it could be a sign that your fueling is a bit out in the first place making the problem more noticeable.

[Steve M]

I installed the second MAP signal to B12 and patched the ground and 5Volt reference wires into those from the original MAP sensor.
My two MAPs do take different initial readings, which will require some re-tuning of VE to recalibrate, which doesn't bother me.

Main MAP initial reading is around 104.3, 2nd MAP (BARO) is around 100.3
Both MAP Sensors are old and were source from wreckers.

I have found a running problem which is puzzling me.

During driving, it all seems to be working fine until the BARO reading intermittently drops and then quickly rises back to its previous reading over a period of less than 1 second.
It's like it resets.
I tried swapping the BARO MAP for another spare item and the same thing happened.
As could be expected, when the BARO drops out, the engine momentarily stumbles.

I've attached a log of the BARO drop-out.

18-12-2020_1.xdl

Does anyone have any idea why this might happen?

ADX used for Logging: OSE_$12PV112_1BAR - Petrol

[vlad01]

Sounds almost like an intermittent short in the wiring?

[Steve M]

Thanks Vlad.
I'll check the wiring again. Hopefully that is the problem and it's easy to fix.

[VX L67 Getrag]

I had a quick look over the log & looks like the wideband is all over the place & pretty rich at closed throttle for the most, the IAC has zero steps at closed throttle too, but I couldn't see the baro drop but was just quick look on fast play(what time does it happen) you've got DTC 13 & 55 active... I think you may need to do a bit more tuning & fixing

[Steve M]

VX L67
The baro drops numerous times in the log. It spikes downward from 100 to 60 or 80.

It is rich on closed throttle, particularly when Idling because when it is not, it does not have a stable idle.
Rich on deceleration I will sort out after everything else.
Zero steps at Idle, the idle screw and throttle linkages like to adjust themselves a bit, I can adjust that out easily.

DTC 13, I'll plug/unplug it to see what happens. It's running closed loop anyway so that will not matter.
DTC55, I don't know what that is telling me, any ideas?