I'm finally getting around to installing my CB Performance Turbo EFI (Quick Tune) system in my IM Roadster. Question I have is where to mount the ECU? CB Performance has been zero help. They keep telling me to mount it under the rear seat. Apparently they've never seen a Roadster/Speedster.

The only options I can think of would be to extend the wiring harness and mount it under the dash or in the trunk. I could mount it behind the seats but I'd rather not have it out in the open. Perhaps I could mount it in the cavity above the transaxle. I'd appreciate your ideas.

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"Apparently they've never seen a Roadster/Speedster."

I have my ECU under the rear seat in my IM roadster. Seriously.  

IM's have a rear seat and a few inches under them to mount the ECU or other things like a sub woofer.  You could make a removable seat that stands somewhat higher than your ECU and it would give you other possibilities.  Just saying.

Once it's dialed in you won't have need to access it often. If you could get it in the back somewhere near the engine, but NOT in the engine compartment(like JPS) I'd do it. The ECU needs to not be in the heat or wet.

You should be able to run a USB cord to an accessible place for tuning. Is there a dry cavity either under the seat or maybe in the side panel behind the door? That would be good. Just away from heat and water.

Good luck.

Bob,s pict is standard IM rear seat on Roadsters and Speedsters.  You can see the carpeted metal piece and the space for holding the ECU and extras. 

The seat is then made out of plywood and covered with foam and leather and they use velcro for attachment and easy removal.  Nice project and especially nice if you want to install a sub woofer under the seat.  You can also do it by cutting some relief in the wood to allow more sound to come through.  So as you see anything is possible. 

You haven't mentioned what your car body is, but all of them have room under the rear seat.  I would find a metal tray or box (or HD plastic, like Tuff Stuff) that would fit your ECU and has a lip around the top edge.  Then use a Dremel with a router bit to cut a rectangular hole in the fiberglass under the seat to drop the tray in.  Check underneath before you cut to make sure you have room where you wish to mount the tray so that the hump at the front of the transaxle doesn't interfere.  

Once the hole is cut just drop it in and wire it up.  Leave a path for the laptop USB cable so it doesn't get crimped.  Drop the seat on top of it and you're done.

I have done this also for a shallow tool box...To mount the ECU under the rear seat, purchase  four dollar  2 - 1/2" deep rectangular a cake pan, test fit and remove the ECU,  flatten the cake pan rolled edges,  cut the seat base opening,  undercoat or bed liner the outer side, run a  bead of caulk and rivet it to the fiberglass seat base, install the ECU.  Or ...mount the ECU on a custom hinge down mount above the 2 x 2 dash cross member.


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