No7Yet

I'm going to be doing a whole lot of o-scope/data acquisition testing
over Spring Break (no partying for me) and need a few things... (I will
be testing both an 87 and 89, so both sets of info would be nice :] )

1) A signal that correlates to engine RPM. I'm thinking the CAS, but I
need to know what sort of signal it outputs.

2) An ignition lead that I can take advance/retard measurements from. I
need to know how it would correspond to (1), and "where" the ignition
pulses would be. I'd ideally like to align (on the scope/DataAcq) the
RPM and ingition timing signals, and measure the time difference between
the two - I can calculate degrees based on time. I'm planning on
monitoring advance/retard on both coils, so I need to know the
independant behavior of each coil in the stock wastespark system.

3) What sort of signal the ECU sees from the water temp sensor.

4) What sort of signal the ECU sees from the AFM (remember, both S4 and
S5, if possible)

5) What sort of signal the ECU sees from the pressure sensor.

6) What sort of signal the ECU sees from the TPS.

The main purpose of my little adventure will be to determine the effect
of the pressure sensor on the stock fuel and ignition maps. If I have
the time/inclination, I'll also be testing the WTS, AFM, TPS, and knock
sensor, independently, and with varying other input levels (e.g.
pressure sensor effect on a warm engine under 3800 RPM at "wot" [AFM
held open ~60% and TPS maxed]).

Also, if anyone can give me any information about tests already
performed, it would be much appreciated. I'll probably want to verify
those findings anyway, but it would be nice to know what to expect.

Thanks,

Brandon

No7Yet

Sorry guys, but I want to make sure that some of the more knowledgeable people see this So I'm going to break my own rule and...

bump.

Brandon

Henrik

Hey there,

1. RPM signal - CAS works for this. If you want to see what it looks like search for my ignition post from about 2wks ago. I posted some 'scope pics, some of them were CAS.

2. I also posted some leading coil ignition pics. I scoped 3 signals, the trigger, coil voltage and cable voltage. You can use the falling edge of the trigger signal as the timing reference. If you scope this with the CAS G signal, it should give you timing advance/retard. I'm not exactly sure where G is indexed to, there may be an offset from TDC but you should be able to see that.

3. Water temp sensor will be a 0-5V output. The sensor will be a few hundred ohms when warm so you'll probably see something close to 0V.

4. Also a 0-5V signal. It should read about 2-3V at idle, dropping close to 0V as the airflow rises. I had a pic in my post of this.

5. Also a 0-5V signal.

6. Also a 0-5V signal. Should be 1V at idle, going up to something over 4V at about 1/3 throttle.

I'de be very interested to see your results. For determining pressure sensor input on injector pulse widths and ignition timing I would suggest that you:

- scope a primary and secondary injector. Below 3800rpm you should only see the primary.
- hold rpm steady at say 2k and 5k. Diddle the pressure sensor while scoping ignition timing. Repeat for scoping injector pulses. My guess is you'll see no change at 2k for injector pulses, at 5k the injector pulses will be affected. Don't know about timing.
- hold rpm steady at say 2k and 5k again. Diddle the TPS sensor. You should see the timing change but probably not the injector pulses.

BTW if you manually force open the AFM at idle, your car will stall (too rich). Also, the easiest point to get the injectors from is probably the resistor block (basically under the AFM) - this will only work for the 87.

Good luck.

Henrik
87TII