I have a 93 1.6L Miata five-speed running a Mitsu. 14B turbo, Voodoo fuel controller, stock injectors, LC-1.
This all started when I was trying to find out why my 91 was running rich, so I checked the O2 and coolant temp sensor readings at the computer on my 93 with my Fluke voltmeter by piercing the insulation on the wire. Then I compared the readings to the ones on the 91. They were different so I decided that maybe my readings were off because of the computer, so I made the stupid mistake of pulling the computer out of my 93 and put it in the 91. The 91's readings didn't change so I put the 93's computer back in the 93. Now it's screwed too
. The only weird thing that happened was when I probed the O2 wire on the 93. It spiked to 9volts and the engine revved up. Then I pulled the probe and it went back to normal.
The problem I'm having with the 93 is that my car seems to be stuck in open loop. It reads 12:1 AFR when it's idling and randomly spikes up to 18:1 and almost dies. Then it goes back to 12:1. AFR does not swing like normal (13:1-15:1). It just stays mostly constant. Also, now I don't get any voltage from my O2 wire. I've put in a new O2 sensor, swapped in 2 other computers, switched my air flow meter, and I still get the same results. My coolant temp sensor still reads the same 2.5-2.8volts and I checked to see if there were any error codes. There were none. I also unplugged the Voodoo. No change. I even bypassed the O2 wire by connecting a jumper wire from the new sensor and ran it straight to the computer wiring harness just before the main connector on the CPU with a T-tap. I also checked for continuity from my T-tap and the metal connector itself in the plastic holder. It was good.
The 93 ran perfect before I started all this.
I don't know what else to check. Please Help.