RyanFlemington

Alright, well I've done the searching, and I've read through the FSM, but to no avail, so I'm asking those who know. I want to reground my ECU(slight 38k hesitation) and I'd rather make my own ground at the ECU than take off the upper intake manifold(it's an 87gx, btw)to get to the stock ground. I know that the 3a and 3g prongs have to be grounded, but for the life of me can't find a plug diagram to tell me which plugs those are. Any help here is really apreciated, and sry if I missed this info somewhere else. Thanks

NZConvertible

The ground wires are on pins 2C, 2R, 3A and 3G. The wires are all black.



More info on the ECU can be found in the Fuel Systems and Wiring Diagrams chapters of the Factory Service Manual. If you don't have the FSM, click here and download it in PDF format for free.

RyanFlemington

most helpful response EVER lol thanks man. much obliged.

Aaron Cake

iTrader: (1)

This will probably help as well:

http://www.aaroncake.net/rx-7/grounding.htm

RyanFlemington

ya, i've read that many times now lol, it's also helpful. any suggestions on a key spots to reground those ecu points, if I'm not gonna take of the manifold? Possibly under the carpet, near the ecu? or should i run a line to the engine and tie in with a major body ground?

NZConvertible

I did the same thing you're planning and for the same reason. All the usual grounding repairs did not fix my 3800rpm hesitation, but doing this did. It's pretty unusual, but there must have been a problem with the ground wires in the harness.

The four ECU ground wires join into two pairs, and also pick up the shield wires for the O2 sensor and CAS shielded wires. These two junctions are just crimped, so I soldered a ~6" wire to each one, and joined the other ends with a single ring terminal. I bolted this to the chassis using the bolt for a harness bracket next to the ECU, after sanding off the paint underneath it. The exact location isn't critical as long as it's a good ground point.

RyanFlemington

ok, cool, thanks, that all really helps. That's pretty much what I had in mind, but it's nice to be reassured.
Any more detail on this. I'm not much of an electrical guy. I think i have an idea, but I'm not really certain, so any more info there is awsome. Thanks a lot.

NZConvertible

Once you see the wires it'll make more sense. Just follow the ground wires from the ECU, unwrapping the harness as far as you need to. The joins are ~6" or so from the ECU plugs.