so by bolting the ecu to the floor pan does that act as a ground for the ecu? just wondering cause i tried starting the JDM tii motor swap project last night and all i could get was the engine to crank and crank, but did notice that the ground wire that bolts to the bellhousing of the transmission and runs to the firewall (and plugs onto a spade connector near the wiper motor) was starting to smoke and get really hot! anybody have any ideas whats going on?

 

No. The ECU itself can sit on a piece of foam rubber and work right. IT's the internal grounding that in some cases needs additional grounding other than the designed grounds which terminate at the top of the rear rotor housing.

The only item on the car that needs it's chassis grounded to the car, are the two coil assy's. That is because the ignitor circuit in the coil assy's gets it's gnd thru the assy's chassis being bolted to the fender/chassis.

IF that wire you mention is getting hot, make sure the batt gnd wire is bolted to the starters long attach bolt AND that that same cable is also bolted to the chassis just below the left strut tower. It the same wire/cable.

Again, the ECU is grounded on top of the rear rotor housing on a series four. Series five???? Got me. To lazy to look. It's gnd location is in the online fsm.

 

yes the negative battery cable is bolted to the strut tower and run right to the bolt right above the long starter bolt, i thought thats where it got bolted to ground, shouldnt make a difference thought should it? i mean thats still ground, got any other ideas

 

http://www.aaroncake.net/rx-7/grounding.htm for all your grounding needs...

 

No idea why that small wire is buring up. It's acting like the gnd b/t the engine and chassis for some reason. No idea here.

 

That's a good enough place to gnd it. I'd go back and look at it again since for some reason the small wire you mentioned seems to be acting like the gnd return instead of the one on the transmission.