ECU grounding
 

I was replacing my carpet
when I came across this
http://img.photobucket.com/albums/v6...7/DSC00135.jpg
Why isn't there wood down here!?
the 944 and the 300zx designers had the sense
why not Mazda
metal plates rust.

http://img.photobucket.com/albums/v6...DSC00130-1.jpg
I've cleaned up all the points, greased everything, made a new ground wire.
the grounding point was rusted to the point of no return.
how was the ECU running at all like this? was it finding ground through it's sensors? and I need a new point in the general area that is known as a reliable ground.

The electronics inside the ECU are not grounded thru its chassis. You can lay the ECU on a foam pad and it works just fine.

The electronics on a series four ECU are grounded on the top of the rear rotor housing.

There isn't supposed to be water intrusion into the cabin around the ECU. Either it's a air conditoning water drain problem or maybe a leaking windshield. Can't say from here.

If you added a gnd wire to the ECU chassis, all you did was make yourself feel good.

Sorry for the under information,
it's a stock S5 'vert
and based on how the interior looked (mostly refreshed now)
the Previous owner left it open through a few showers..

there was a ground wire from the Ecu harness grounded into the bracket that holds the ecu in place under the shield.

EEEK! That's rough, man. Is the rest of the car that rusty? I'm battling a rusty car as well :tear: .

Oddly enough
there's no rust in the rest of the car
well there wasn't any that wouldn't come off with even a trivial amount of scrubbing.
that bracket/cover was the worst part.


http://img.photobucket.com/albums/v6...DSC00127-1.jpg

I've been dealing with rust and corrosion for a long time
first job was at a boat yard, so electronics and all sorts of things

Yeah. I made sure to put that SERIES FOUR in there when I wrote that. Never touched a series five, but somewhere I've heard a series five does have a gnd wire in that area.

That said, I've had problems with hesitation on a series four and added an additional gnd wire to the stock ECU gnd wires..........and bolted the other end of that new wire........to the ECU mount bracket (close by and a good ground point to the chassis.)

Someday when you have nothing to do, undo that one gnd wire and see if the car runs funny or not.

Just for fun, I looked at series five WD and the ground at the ECU is ground number 10 and is used exclusivley for the 02 sensors ground. See attached jpgs.

See the green line on the attached jpgs.

You sir
Rule.
If you're ever in Panama City, Fl
(or Tyndall AFB)
let me know
I'll buy you a beer

How about Lajes AFB in the Azores? Bowling alley beer and Portugese hamburgers! Kidding. Darn, forgot the beers name.

EDIT: Sagres beer and the bull fights.