Ground wire question
 

I'm getting ready to go through and clean/replace the ground on my '87 TII. My question is, should I try to run them all to a common ground point, or is it better for them all to ground in different spots? I remember seeing central ground kits being sold for various older imports like the TSI and RX-7, but remember also reading some mixed opinions on it.

Ground it to different spots.

That's what I was thinking. Just curious, what is the supposed reason behind using a central ground? I guess basically I'd like to know the pros and cons of each way.

read Aaron Cake's writeup on regrounding.

basically you need to pull the UIM, clean that ground, then run a ground at the ECU. That's what's going to affect engine performance.

When you say "them all" I guess you're running a bunch of extra wires? As long as all the factory ground points are in good shape then extra wires are of very little benefit. They weren't needed when the car was new so there's no real need for them now. If you do decide to add some, all you should bother with is battery-to-chassis and engine-to-chassis. These write-ups with a dozen wires connecting every part in the engine bay are nonsense. But first you should recondition all of the stock ground points.

http://aaroncake.net/RX-7/grounding.htm

Snake oil...

Actually, IIRC the kits replaced the original ground wires/straps w/ new ones, and ran them from the factory locations on the engine to one central ground on the firewall or inner fender. In other words, all ground wires coming off the engine are run to one common ground point on the chassis. I'll see if I can find a link to what I'm talking about.

Here are a couple examples, these ones run all grounds to the battery negative terminal it looks like.

http://cgi.ebay.com/ebaymotors/UNIVE...spagenameZWDVW

http://cgi.ebay.com/ebaymotors/UNIVE...spagenameZWDVW

And here's the super duper high-dollar Apexi model :)

http://cgi.ebay.com/ebaymotors/APEX-...2em118Q2el1247

The only difference those kits will make is to make the engine bay look like a cluttered mess. There is absolutely no scientific basis behind the claims the sellers make.

the only grounds that affect engine performance are the 4 ground wires coming from the ECU. They are crimped together at two spots. Many people run extra ground wires from the spot of these crimps.

That's what I thought. Thanks guys.

Yeah, I searched ground wires, I plan on making sure those are grounded good, since I noticed a bit of the 3800rpm hesitation the day when I took it down the street to put some fresh fuel in it. I just could find anything about those kits for the underhood grounds. I thought it was a load of hooey, but wanted to make sure:)