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Author Topic: connect two OBD2 with splitter?  (Read 13925 times)
vtraudt
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« on: September 04, 2013, 10:54:12 AM »

I am trying to data log 1.8T AEB.
VAGcom through OBD2 does not have boost, and certainly no A/F ratio.
The Innovate LM-2 logger has failed so far to sync on rpm; signal all over the place when I spliced into the ECU signal to coil 1.
The LM-2 only allows logging of 4 parameters.
I want to either:
a) use VAGcom to log OBD2 data, and LM-2 with wideband O2 for A/F, sync afterwards via rpm

I thought about using an OBD2 splitter and connect vagcom AND LM-2 OBD2, but was told by Uwe (Rosstech/VAGcom) that the K-line won't allow 'split'.

Any suggestions how to log the AEB?

Other methods or tie in points for the LM-2 rpm signal?

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2002 Allroad 2.7T 6spd stage 2
1998 A4 1.8T 5spd stage 3
1996 A4 2.8 auto stock
julex
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« Reply #1 on: September 04, 2013, 11:43:30 AM »

Tach signal at ECU or cluster works for me.

You cannot split K-line, tried myself and it just doesn't work.

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vtraudt
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« Reply #2 on: September 04, 2013, 12:32:51 PM »

Tach signal at ECU or cluster works for me.

Happen to have pin or connector or photo or sketch or similar to locate correct tie in point/wire for the AEB?
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2002 Allroad 2.7T 6spd stage 2
1998 A4 1.8T 5spd stage 3
1996 A4 2.8 auto stock
ddillenger
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« Reply #3 on: September 04, 2013, 01:01:08 PM »

Happen to have pin or connector or photo or sketch or similar to locate correct tie in point/wire for the AEB?

Blue plug on the back of the cluster, pin 11 is engine speed signal.
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terok
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« Reply #4 on: September 06, 2013, 01:29:09 AM »

I'm using VCDS for logging and VEMS Round for A/F ratio. Round is connected to ecu RPM output and it also feeds simulated narrowband signal to ecu, works like a charm. Also option for EGT sensor is nice.
With newer round V2 you can connect rpm and 4 different analog inputs to it, so you can attach pressure sensor for example and log everything via VEMStune. They do advertise an extra analog input also on older V1, but in reality it's useless.

I would imagine the same would be achieved with LM-2.
« Last Edit: September 06, 2013, 01:31:12 AM by terok » Logged
vtraudt
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« Reply #5 on: September 06, 2013, 04:23:26 AM »

Is vems a gauge or logger? Quick glance at their website shows a gauge setup.
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2002 Allroad 2.7T 6spd stage 2
1998 A4 1.8T 5spd stage 3
1996 A4 2.8 auto stock
terok
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« Reply #6 on: September 06, 2013, 05:43:47 AM »

It's a gauge, but will log or display real time data when laptop is connected by serial port.
All the intelligence is just packed into a gauge form. Also possible to control boost solenoid, but i think while it works, it's still in development phase.
Meant really for permanent installation. LM-2 can be made more portable.

I haven't been missing lambda/AFR logging, as i can get everything i need for tuning with VCDS. Mixture and rpm info i get from gauge display as i go along. Not the best solution of course.
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vtraudt
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« Reply #7 on: September 06, 2013, 06:24:11 AM »

"optical" logging is cumbersome (I currently do that for boost, since AEB have not MAP), videotaping, then converting video information into excel data points for sync with VAGcom data.

Suggestions (make/model/source) for adding a loggable boost sensor?

I will take the cluster out today to see if feeding the RPM signal to the LM-2 provides better results.
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2002 Allroad 2.7T 6spd stage 2
1998 A4 1.8T 5spd stage 3
1996 A4 2.8 auto stock
vtraudt
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« Reply #8 on: September 07, 2013, 09:55:14 AM »

Blue plug on the back of the cluster, pin 11 is engine speed signal.

What wire color is pin 11 the blue connector? Need to splice into it obviously to run signal to LM-2.
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2002 Allroad 2.7T 6spd stage 2
1998 A4 1.8T 5spd stage 3
1996 A4 2.8 auto stock
terok
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« Reply #9 on: September 07, 2013, 02:07:02 PM »

Wire color might be green/blue (did not check, just googled).

LM-2 on obd-port propably wouldn't work anyway, because AEB ecu does not support OBD2 standard communication.
I checked the user manual of LM-2 and it says that it has analog inputs for use of your own sensors.
So you could wire up Motorola MPX4250 (max 250kPa abs.) for example.
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eliotroyano
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« Reply #10 on: September 07, 2013, 09:46:05 PM »

Tach signal at ECU or cluster works for me.
You cannot split K-line, tried myself and it just doesn't work.

Basically the K-Line electrical signal is just like a pseudo RS232 serial signal with square shape and electrical levels going from 0-12Vdc. It can be replicated or splitted but you will need a powered serial Hub to do it. Although it can be done the solution is not cheap.
« Last Edit: September 07, 2013, 09:54:58 PM by eliotroyano » Logged
eliotroyano
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« Reply #11 on: September 07, 2013, 09:54:17 PM »

Blue plug on the back of the cluster, pin 11 is engine speed signal.

T32/11 pin comes from the pin #6 of the ECU, you can take the signal from any of that pins, but you will need a pull-down resistor to allow it comes down less than 1v then it allow LM-2 recognize it as square signal with "logical" TTL levels. Less than 1V is "0" or lower state and more than 3V is a "1" or up state. Then RPM comes from the frequency of that signal, and it states change from "0" --> "1". I hope that can help you.
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Sirocco20348
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« Reply #12 on: September 08, 2013, 02:00:37 PM »

For the AGU, you can calculate boost by using the formula after collecting some data from vagcom:

Logging 002 for Air Mass In, and 012 for rpm.

Boost pressure in bar = ((maf (g/s)*53.47)/rpm)-1

Not sure if this helps.
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