What is the correct method for picking up a signal from a 3 bar map. I will be recording both rpm's and boost. i have the ME-R and I'm thinking that I could pick up a signal for both ( tach and boost ) from the ECM harness. Would this impose to much of a current draw on the 3bar. Any advise, or do's and don'ts. Brian
RPM cable for LM1
- Thread starter Fuelie600
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The input impedance of the lm1 is high enough that you shouldn't have any problem tapping into the ecm wire that carries the map signal for the ME-R. I tapped into the crank sensor input line to the ecm for rpm, but Klaus at Innovative says that in lots of cases it can get a good enough signal if you just wrap a few turns of wire around a coil wire and connect that to the rpm input. The crank sensor line will be carrying much less current but it is quick to test and if it works that's one less wire to tap into. Please post back if this works - I may redo my wiring if it does.
ijames, Are you suggesting the wire which goes to the sensor itself. You mentioned that you already tapped into the ECM crank trigger input. Could you clarify this. Seems the ECM harness would be the most sensable for rpm and ( w/ ME-R MAP input ) the boost also. Later Brian
I meant that you should try taking a wire and wrapping it several times around the wire in the ecm harness right at the ecm that carries the crank sensor signal, and connecting that to the rpm input on the lm1 cable. That would save you from physically having to tap into that wire either by scraping insulation and soldering, pulling the pin and soldering onto the end of it, or with a scotchlok-type connector (worst choice). Best case, you're done, worst case, you still have to tap into the wire if it doesn't trigger reliably. Klaus says that the rpm input is sensitive enough to do this out at a coil connection on other cars so it might work here. This is all for the rpm input. For the map you will have to physically tap into the wire and connect it to one of the other lm1 inputs, and again, as you say, right at the ecm is the easiest place for you to do that. Hope that's clearer 
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.Recieved my RPM cable today. Has anyone tried picking up a rpm signal from the ECM output to the factory tach as the instructions state? Ijames, when you tapped into the ECM input from the crank trigger, did you not set the software for waste spark mode? Thanks Brian
The factory tach signal doesn't come from the ecm, it comes from the ignition module. I think it passes through that big connector at the right side of the dash, above where the ecm sits, that also carries the map signal from sensor to dash, but I haven't looked at the wiring diagrams in a while to be sure. Using the crank sensor signal I used 6 cylinder no waste spark.
