I have a 1986 s4 N/A. stock.
I have cut the ground wires at the ecu to reground to "fix" the 3800rpm stutter. i noticed that there wasnt a bolt holding any grounds where aaroncakes guide said they were under the manifold. Can i ground the ecu to the floor board/chassis or does it need to be back on the block? i attached it to the bolts that hold the kick panel on (sanded them to the metal) but it wouldnt start the next day(go figure). any help would be appreciated. thanks! ps ive searched for the past few days before making the post.

 

It's best to have the main engine ground grounded to the engine block. If you took a meter to the grounds you have they should read 0 volts w/key to on. If they have voltage on them then they aren't grounded properly.

 

It should be grounded to the engine as Satch said. However, given the criticality of these grounds to the car's function, giving them each a redundant ground to the body, such as on the passenger side strut tower, would be a wise idea

 

And when you say you cut the grounds at the ECU did you add a wire to each cut wire so as to reconnect each one to the ECU or not?

 

Yessir. Basically the ground that was supposed to be on the block wasn't there. Bolt and everything is missing. So I took the two grounds on the small plug, cut them and soldered new 12g wire in there place. I grounded them to the floor board though. Obviously wrong based on the replies I received. So tomorrow I will de solder and attach longer wire, run through the fire wall to the proper grounding point. Sound like a plan?

 

Pins 2C, 3G, 3A and 2R are all grounds (3A and 2R are spliced to each other).

 

Here's the details on 2nd gen grounding:

Proper RX-7 Grounding Procedures

 

Thanks guys. Trust me Aaron I've looked at that guide for days lol. Do the other above stated grounds by satch all converge on the same ground point on the block? 2c and 2r as well I mean.

 

Guess this explains what I need huh?