Been lurking on this forum for awhile and just got a quick question. When using the stock wiring is there any issues that arise that I should be aware of. I plan on using the stock wiring so that if I have an issue with the MS I can switch over back to stock and make sure that everything is running properly. I'll eventually make my own harness but looking to be able to switch back to stock for drive ability while I am getting used to tuning and such.

 

The Megasquirt is more sensitive to electrical noise than the stock ECU is. Grounding and shielding are important.

 

So that would be pretty much the only main issue right? Assuming mainly with the CAS. Forgot to mention this is for a stock NA s4. I might just run new wires for that from the get go.

 

if you run new wires for the CAS, make sure that they're shielded like the stock ones.

Also, unless you want to keep the MAF, you'll need to find the wire for the fuel pump switch that runs to it and re-route it to the MS.

Any other issues with the stock wiring are related to age; the wire coatings can become brittle and crack over time, and the copper can oxidize, making it a royal PITA to solder.

 

One of the advantages of any standalone is being able to get rid of the old stock wiring.

 

Completely forgot about this


I plan on moving over to a new self run harness but for now so that I can still have a good running car just in case something goes wrong with the squirt, or I can't seem to get the tune down, I could just switch back over to stock. However at this point in time I am actually considering just going the distance from the get go, I'll have my Jetta by the time I plan on getting the squirt so I could probably just run a new harness and tune it.

 

Was I dreaming or did I see somewhere that had an adapter cable to be able to connect the MSII directly into the original CPU harness? My CPU just puke and not getting anything out of it voltage wise and need an emergency setup to be able to get the MS in and running until we get a long enough break between races to do the rewiring. I have looked several places and haven't found such an adapter so maybe I just dreamed that.

 

There is an adapter, although right now we don't do MS2 with the plug 'n play officially. I could easily do it though.

I do recommend building your own harness though.

Ken

 

The use of the adapter would only be for long enough to get me through the next race or two. I have a nearly full month space a bit later that I could use to do the complete rewire. Where could I get the adapter for use as a temporary fix to put in place to allow me to get the car running again while I build the new wiring harness? So I can figure out what to do for IAT sensor in order to get rid of MAF and other issues I need to resolve for the rewiring. I am also looking into just replacing the stock computer with one I have from another RX7 but worried a bit since it is from an 86 automatic and not an 87 manual shift. Not sure if there is anything different between those two. So looking for any and all options to get running as quickly as possible while still moving to MS for future improvements.

By the way I really appreciate the quick responses to my sometimes really stupid questions. I am a bit nervous about this huge step for a rank amateur in the EFI field. I understand the basics and wiring, just nervous about the tuning aspects and the start up.