I happen to log with Logworks and Evoscan. With Logworks I log RPM via the Tactrix cable and RPM via the LMA2/LM-1. With the Tactrix cable the RPM logged with Logworks is steppy and needs to be smoothed out to 0.41 seconds. When smoothed out, the rpm via tactrix is almost the same to the rpm via LMA2/LM-1.

Now here is the puzzle. Today I did a log and ran it through DLL power graphing. I ran one log using LMA2/LM1 rpm and the other log using Tactrix cable rpm. Check out the results:

The tactrix rpm gave me 325 hp up top while the LMA2/LM1 gave me 304 hp up top. This is the SAME log, boost, timing, AFR. The only thing is that the rpm was logged two different ways.

Very Interested as to why this happened? And which one is the "correct hp output?

 

Well, as you stated, you had to smooth one of them. The smoothing itself is going to mess with the HP readings.

I would personally go with the LMA2/LM-1 RPM and don't worry about absolute numbers. Just use them as comparisons from run to run.

Also, you have to understand that the RPM logged with logworks is going to be somewhat steppy when logged from the ECU because of the resolution within the 1 byte. The formula is 31.25x, so there will be a step of 31.25 RPM. You won't get any better resolution than that unless you log 2-byte RPM.


Eric

 

where are you getting your RPM signal from with the LM-1? tapping into a wire at the ECU?

 

I tap into one of the plugs that goes into the ECU. I squeeze the new wire in the same pin hole of the RPM signal wire. That gives a very tight contact. Then I zip tie both wires so the new wire will stay in place.

 

I use logworks for my LM-1 + RPM converter setup on my Stealth to get RPM from the ECU pin, TPS, WB02, Fuel Pressure and Boost. I use my Pocketlogger/Palm to get RPM/Knock from the ODB port

the RPM's don't match and the sample rate is much different.

 

Try further increasing the smoothing interval for the rpm logged via the Tactrix cable.