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Single wire temp probe?

Posted: Fri Mar 14, 2008 8:57 am
by clayw
The answer to this may be in another post that I haven't found yet, so feel free to redirect me!

I have an MS2 unit with BG Firmware 2.862 and Megatune 2.25. I'm setting up EFI on my `76 BMW 2002 M10 motor, similar to this:

http://www.finkbuilt.com/blog/fuel-inje ... -complete/

Like Fink's conversion, I am trying to run EDIS first, then add the EFI later. Right now, I have the EDIS stuff in place and, when I jump it (battery to be replaced soon!), the EDIS4 stuff runs on it's default setting(10 degrees BTDC). Due to some faulty wiring, I can't yet get the MS2 Unit to run the advance. Soon it will be fixed!

My question
(finally) is: I'm using a BMW white-top temp sender, but it only uses one wire and grounds itself to the motor. Do I just wire up the single line to the relay board? Do I need additional wiring or will this be enough?

Thanks in advance!

Posted: Fri Mar 14, 2008 3:16 pm
by 73Eldo
Single wire temp sensor should be fine since even in the 2 wire ones one side is ground in the MS anyway. Single wire just increases your chances of ground differentials. Are you planning on sharing the same sensor for your stock ECU and the MS? If so you better read up on that in the manual because it cant always work and if it can there are mods that need to be done.

Posted: Sat Mar 15, 2008 9:28 pm
by clayw
Actually, I drilled and tapped an extra boss on my water neck and installled another sensor. Either way, my car never had an ECU. Megasquirt will be her first!

Thanks for the advice. I'm a compulsive grounder, so I'll make sure that all is grounded well.

Posted: Sun Mar 16, 2008 5:01 am
by 73Eldo
Also remember most thread sealers are non conductive. Many single wire sensors warn you not to use sealer.