Thread: Innovate LM2?
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flatsix777 flatsix777 is offline
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Join Date: Apr 2007
Location: London, England
Posts: 11
I installed an LM-2 a while back and log AFR, RPM, Boost, Oil Pressure and Oil Temperature. It’s not “plug and play” as you need to get a very clean RPM feed and also reduce the signal voltages on the other sensors. I used the stock boost sensor and it works fine, although it's obviously reading boost before the throttle plate so gives a slightly different reading to my mechanical guage. The LM-2 has generally been fine but does freeze occasionally. I used an 18ft cable and have the unit in the glovebox.

For RPM I started by trying to use the tach signal out of the CDI (Blk & Violet) but this was useless and so in the end I hooked it up straight to the coil (-ve terminal). This produced a very random & unstable reading so I used miniature co-axial cable with a steel shield (earthed at either end) to clean it and then smoothed it by running the signal into the LM-2 through a 1M potentiometer, acting as a voltage divider. By tuning the pot you can damp out the spikes leaving a stable output. You need to configure the LM-2 in the relevant sub-menu; settings aren’t very clear but the ones I’m using are:
• Falling edge (you have a choice of rising or falling edge on the configuration menu.)
• Cal 6 – 3 pulses per cycle (you have around half a dozen choices to configure to different numbers of cylinders).

The three potentiometer terminals are connected up as follows:
• The two outer ones go to ground (same place as the earth for the LM-2 power supply) and to the tach signal (from co-ax) respectively. Doesn’t matter which way round.
• The middle terminal goes to the LM-2 analogue feed (RPM +ve Blk/Wht)
• The co-ax shield goes to the common earth and the LM-2 RPM –ve input (Blue) also goes to common earth.

Mine looks like this:

The AFR signal was straight forward:

I took signals from the sensors for boost, temperature and pressure into the available analogue inputs on the LM-2. The difficulty is that the LM-2 can only accept a 0-5V input so it’s necessary to reduce voltages. I used a 10K pre-set potentiometer for each signal, a 5.1V 0.5W Zenner diode on the output to the LM2 (between output & earth) to protect it from any spikes above 5V and also a 1K 0.6W resistor in series on the input to the pot. I simply followed a diagram in the LM-2 manual. It's then just a matter of setting the pot to give the right ratio reduction; in my case 49% reduced for temp and 36% for oil. Here's what the reducer looked like:

Calibration data that I used is as below:

Here’s a screen shot of data in logworks:

Good luck & hope this helps.

1984 ROW 930 - Stock except Rarlyl8 1-out, Andial IC, Air Pump delete, Carrera & Setrab Coolers, 0.8bar & LM-2
Old 04-02-2010, 05:13 PM
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