I want to check the o2 sensor signal at the ecu but i can't find which pin on the ecu it is? does anyone have a link to the relevant diagram?
it's a 1989 t2

 

http://www.teamfc3s.org/main/factory_service_manual/

 

http://www.whoistouching.us/rx7/s5wiring/

 

Thanks guys!


is there anything else you can suggest that might be causing it to run really rich?

 

The 02 sensor only works in *closed loop*. In other words the car has to be driven for the 02 to effect the ECU.

If too rich at IDLE, I'd suggest to idle the car and then go to the FUEL PRESSURE REGULATOR and pull the vacuum line off it. It should have vacuum on it. If it does, then that's not your problem.

A dirty air filter might effect it at idle or driving. I'm sure others have opinions on this.

The 02 wire is on pin 2C of the middle ECU plug. They count the plug starting from the top right, then to the bottom right in a up/down fashion til you reach the far left of the plug. The color is pure black. Should be the second wire over from the top far right.

 

HAILERS, maybe you can answer this, I don't know if its just a typo in the FSM or not.

If you look at the S4 pinout table you will see wherre the o2 sensor pin is. I forget which one it is but It says "GY" for the wire color when infact its black....

What does GY stand for? I though at first it was G/Y but the wire is black.....

 

You can forget the O2 sensor. If it's not working properly it doesn't cause the engine to run excessively rich as some think. In fact unless you were either logging cruise AFR or calculating average fuel consumption, you'd never know it wasn't working.

How do you know it's running rich? When is it doing this?

It's not a typo but it is misleading. The O2 sensor wire is shielded and the outer insulation is grey (GY). The shield wire and outer insulation stop a few inches back from the ECU and the inner insulation is black.

 

It smells very rich?
gas mileage is high but then i've never had one of these cars before?
probably 16/18 mpg i'd say.

 

Thank you NZConvert.

 

The only time you're going to be able to smell the exhaust is when it's idling, and a rich idle mixture has nothing to do with mixtures while driving. In fact it's fairly normal.

Fuel consumption varies massively with driving conditions, so unless you monitor average fuel consumption regularly and notice a jump, mileage won't tell you much about mixtures.

I'm assuming things are generally in good condition, like filters, spark plugs, timing, no vac leaks, etc...

 

new plugs, leads, oil filter, oil, coolant, tps and timing adjusted to spec, grounds done.

new air filter on the way,
how do i check for vac leaks?

 

Here's my intake pressure tester: https://www.rx7club.com/2nd-generation-specific-1986-1992-17/water-sensors-water-pump-diff-models-583211/ (Scroll down to posts #11 and #16)