LongDuck

Have been seeing some posts on several different 1st Gen discussion boards about a diagnostic plug located somewhere in the SE engine bay that allows you to hook up two LED's that will flash in sequence to determine engine/O2/AFM/etc. codes.

Does anyone have any links to this technical writeup, or have any first-hand experience? I would definitely like to get this setup on my car to monitor potential issues, and have even read that the O2 sensor has a reading which translates to a rough gauge of mixture setting.

Thanks, in advance,

bizarro

iTrader: (1)

When getting my car the guy @ rx7world hooked this up although I had an 84 gsl-se...would this be what you are looking for?

http://www.rx7world.com/Tools/Tools.htm

LongDuck

That looks like it - for members here, I've included a quick picture to show what this looks like:



Given the description used by the seller, it appears that this is utilized in much the same manner as the TPS plug outlet that's located next to the AFM on the passenger-side strut tower. If this is the case, it looks to be a very simple 2-lead, 1 ground, wired light array. If anyone can confirm this, it would lead me in the right direction (minus the $45 for a 'pre-built' part).

Also, any leads on indicator codes and their meanings would be greatly appreciated. Thanks to the forum for your knowledge and expertise.

bizarro

iTrader: (1)

I don't remember much about the codes but I do remember he adjusted the TPS till the #2 light was lit and the #1 light was off...at that point he turns to me and said..."It's set! Lets take her for a test drive..."

LongDuck

I've used a similar setup to check and set the TPS, and I thought I'd remembered reading that there were some diodes and resistors that had to be wired in series to get the LED's to 'pull down' resistance and work correctly. Perhaps the use of standard filament-type bulbs precludes the use of a specific design.

Thanks again for your leads on this,

bizarro

iTrader: (1)

no prob glad to help...although I don't have much info on it 'cept that this guy is WELL versed in RX-7's...all three!...when we turned her on, he found all the idle problems and corrected them within 20 mins of turning her on...i was amazed because i've read on the forum of people hunting and asking how to fix idle problems for days...i was just glad he was around to help clean up the idle best he could...not to mention it was pitch black out and we were working off of flash light...

gsl-se addict

iTrader: (3)

Yes, you can use a simple two light setup to check error codes on the ecu. I have tried both LEDs and regular filiment bulbs and both work fine. The connector is located next to the ecu, whereas the test connector is located in the engine bay for the 86-88 years.

Check :
http://www.wankel.net/~krwright/cars/rx7/85_manual.html

and click on the link for 13b fuel and emission control system. The codes are listed on page 71. Connect your two-light tps tester to the fail check connector. The common wire goes to the red wire w/ white stripe connector and the other two ends go to the other two connections in the connector that have wires leading in to them (red wire and a green wire. Turn on ignition both lights will be on and one will then turn off atfer about 2 seconds. I don't remember which one of the lights blinks, but it should be obvious. If there are any errors, the light that turned off after two seconds will start blinking. Use page 71 of the FSM that I previously mentioned to determine the code.

BTW, if there is more than one code present, only the lowest code will be presented until that error is fixed. I believe that you can check the O2 sensor also, but I am not sure if the second bulb will report it or you may have to connect to the O2 check connector located in the same area. Hope this made sense. Let me know if you need any more clarification. There is no need to spend $45 for two lights and a couple wires.

Kent

LongDuck

Hey, Kent - thanks for this excellent information. I am looking for more clarification on several things, however;

1) precisely where is the engine code connector located, and do you recall the color/configuration of the plastic connector so that I will recognize it when I see it?

2) You mentioned the O2 check connector - is this the connector used that will help to give a rough indication of stoichiometric balance for air/fuel? I've read that you can hook up a light to one of these to show rough lean/rich mixtures, which would be valuable for EFI tuning.

Also, does anyone know what the plastic connector by the AFM that has the green rubber boot around it is used for? I've always wondered if this was a diagnostic/test connector for something. Thanks a bunch!

gsl-se addict

iTrader: (3)

LongDuck,

Both of the connectors are located next to the ecu (under the passenger side floor). Both are shown in section 50 (wiring diagrams) of the website that I gave you eariler. I know the files are large and my take a while to download, but they are great to have. I printed them out and use them all the time when I am working on the SE. The fail check connector has six slots (three on top, three on bottom, but there are only three wires leading in to it (Green, Red, and Red w/ white stripe). The Red w/ white stripe goes to the common connection of the two bulbs and the other two wires from the bulb go to the connector with the green wire and red wire.

For the O2 check, I am not sure. The FSM uses a checker from Mazda and doesn't clearly state the wiring, but they do talk about the proceedure to see if you are on the rich or lean side. I am not sure if you can adjust your mixture accurtely this way since the O2 sensor needs to be hot to be accurate. It appears that the second bulb that is hooked up in checking the fail codes. I tried this, but it did not appear to work. It is probably due to the fact that I am running rich (fuel pressure too high). If this is the case the second lamp just stays on. If you are close to ideal, the lamp will blink. There is another connector shown if the FSM as being the O2 sensor check connector. You could connect a volt meter between the Red/ white stripe wire an the connector with two incoming black wires on the O2 sensor check connector. If the voltage is above 0.5 volts at a certain point, you are on the rich side. Bellow 0.5 volts indicates lean condition. The O2 sensor check connector has 7 pins with three wires running in to it. I believe that it is also next to the ecu.

BTW, the connector that you are talking about next to the AFM is probably the fuel pump short connector (has two pins, right?) This allows the fuel pump to run when the engine is not running to test things like fuel pressure and injector leak tests. If you put a jumper there, the fuel pump switch in the AFM will be bypassed and the fuel pump will run whenever the key is in the on position.

Hope this helps some. Also, feel free to PM me anytime if you have further questions. I will try to help the best that I can.

Kent

LongDuck

Very helpful, thank you. Incidentally, I went out to Mazdatrix and bought the 84 FSM for my SE. I've been putting together information from so many sources, I decided to break down and just get the right tool for the job.

I really appreciate your knowledge and assistance,

gsl-se addict

iTrader: (3)

That's good that you got an FSM. They are vey helpful. I was too cheap to fork out $84 for one, so I just downloaded mine. I have a high speed connection in my office, so it didn't take long. Since, the ecu only has 6 error codes, you won't be able to diagnose everything that may be wrong in you car, but will help at least on the fuel side. I had to pretty much figure this testing thing out a few months ago and found that my AFM was bad by using the error checker. I am glad that I could help some.

Thanks,

Kent