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Megajolt Install Question: VRef and TPS Sensor

Posted: Fri Jan 09, 2015 1:15 am
by bladerunner80
Hi all, first post! I will be starting my megajolt install on my bug this weekend and doing some final reading and installation prep and I have a quick question. Can I use the VRef and Negative pins on the megajolt box to power my TPS sensor for my air/fuel meter? I'm installing a TPS sensor on one of my carbs to use with my Innovate LM-2 and I read the VRef pin on the MJ box provides a 5v power lead which the TPS sensor needs. I'm assuming the TPS sensor drawing power from this pin wouldn't interfere with the MAP sensor operation (I'm using the MPA sensor for ignition)?

Thanks!

Re: Megajolt Install Question: VRef and TPS Sensor

Posted: Fri Jan 09, 2015 5:08 am
by miniman82
You may run into ground loop issues if the two units are grounded at different places to the chassis, and I question why you would split the map and tps signals between them anyway- makes datalogging a pain. Put both of them on the Megajolt, it's easier that way.

Re: Megajolt Install Question: VRef and TPS Sensor

Posted: Fri Jan 09, 2015 6:17 am
by Piledriver
It appears MJ makes you pick one or the other. One input.
http://www.autosportlabs.net/Choosing_b ... MAP_or_TPS

There is mention of another input for "corrections" that might be loggable.
All your data in one log for analysis (and good analysis software) is almost essential.

(All I know about MLJ is from 30 seconds of Googling and skimming through the docs)

Even having to simply go back to MS2 from MS3 for a few weeks drove me nuts, even the small reduction of (mostly idle related) features was frustrating.

Re: Megajolt Install Question: VRef and TPS Sensor

Posted: Fri Jan 09, 2015 12:14 pm
by bladerunner80
Thanks for the information. My plan was to output the AFR data from the LM-2 (via the optional expansion cable) to the aux input on the megajolt box. I'll make sure to ground everything at the same location.