Hello, I am new to RX7's and rotary motors. I just bought an '87 RX7 and it needs some work. My tachometer only works some times and when I looked under the dash I saw that some tard removed the stock wiring harness for the ECU and wired a new molex connector on it. There is a ton of needless spaghetti wiring down there too so I can't make heads or tails of it. Basically I want to know it the rotary motor can take an aftermarket tachometer, or do I have to buy something special?

 

You should fix the damaged wiring first before trying to modify it. Who knows what's been done and to what end...Stuff like that leaves you at the side of the road.

As for the tach, almost any aftermarket tach will work fine as long as it can be configured for a 4 cylinder.

 

Yeah the old molex connector for the ECU is just hanging there and my car has a bunch of wire caps on it. It's a horrible mess, do you think I should even try to make heads or tails of it or just replace the entire wiring harness? My tach decided to work this morning If I replace the harness I'd like a good one, what do you recommend?

BTW I thought that the firing order was closer to a 6 cylinder than a 4 because each rotor has 3 sides. Am I mistaken?

 

There are 3 sides per rotor, but only 2 are used during a full revolution of the eccentric shaft.

 

To the Poster of this Thread..Please,Oh God Please!..just listen to what Mr Aaron Cake has to say.He does know his stuff..Trust him!..

 

Well on the electronics side of my car it looks pretty bad so where should I look for a mid to high grade wiring harness? I once heard that there was a company that made custom one's and actually printed the function of each wire on the ends and shielding. It takes the hassle out of wiring diagrams etc. (Although this was for old muscle cars)

 

sounds like your thinking of painless wiring company
the harnesses they make are only for the other components of the car like power windows etc. they do have ignition and some of that wired in but it sounds like you need the motor harness which the only ones painless make are for like you said older muscle cars

 

There aren't any aftermarket harnesses for the 2nd gen that are not designed for standalones. That is to say, no stock replacements. The dealer will charge about $700 for a new one. If you can find one in good shape used, then go for it. But keep in mind that these are 20+ years old and many are in very poor condition.

Or, you could get as set of ECU plugs and splice them back into your harness if the damage is only concentrated around the ECU.