quote Originally posted by Patrick: The EGR valve only opens under certain conditions while driving. On the OEM style EGR valves, you can actually open the valve by hand by sticking a finger up through a hole on the underside of the valve housing and pushing the valve open. The engine will stumble. If your EGR valve does not have the holes in the underside of the EGR housing, a vacuum pump will open the valve... and again, the engine should stumble. I personally don't feel your elevated idle RPM speed is EGR related.

Another way to test the EGR valve is to remove the vacuum hose and open the valve by hand by sticking a finger up through a hole on the underside of the valve housing and pushing the valve open. While open, put a finger over the port where the vacuum hose goes and release the valve. If the valve diaphragm is OK, you should feel suction at the port and the valve should remain open, Removing you finger, the valve should close.

Paul, the instructions for the cable in your link says it won’t work on 85 V6’s and that’s what I have. Strangely, the other one that’s $114.95 does say it will work with 85 V’s. I’m confused. 🙁
Also, I really would like to bite the bullet and get the scan tool, especially because it seems these idling & driveability issues are non-stop. 🙁
Patrick, as I mentioned previously I’m going to do the iac port block off ((while running) test today.
Vintage- Nut (and others) thanks for the info on the egr valve. I will test that later with the Mighty Mite and see if I can verify operation.
Kit

And remember to try your spare MAP sensors.....

Kit,

The Coolant Temperature Sensor (CTS) goes to the ECM. Based on this ECM circuity and the coefficient direction of this sensor, the voltage to the Analog to Digital Converter (ADC) inside the ECM rises as temperature goes up. So it has a positive temperature coefficient overall.
My GUI displays this as raw hexadecimal, raw decimal, and in degrees F or degrees C.

The Manifold Air Temperature (MAT) Sensor called the Intake Air Temperature (IAT) Sensor on the Fiero goes to the ECM. This nomeclature difference is because GM decided to measure air temperature at the Air Cleaner rather than in the Intake Plenum (Manifold). Based on this ECM circuity and the coefficient direction of this sensor, the voltage to the ADC inside the ECM falls as temperature goes up. So it has a negative temperature coefficient overall.
My GUI displays this as raw hexadecimal, raw decimal, and in degrees F or degrees C.

The Manifold Absolute Pressure (MAP) Sensor goes to the ECM. Based on this ECM circuity and the coefficient direction of this sensor, the voltage to the ADC inside the ECM rises as pressure goes up (or so called vacuum decreases). So it has a positive pressure coefficient overall.
My GUI displays this as raw hexadecimal, raw decimal, and in inches of Mercury (inHg) or millimeters of Mercury (mmHg).

When I was coding my GUI, I found tables (similar to the CTS table shown previously). I also measured their resistances at 0 C, 25 C, and 100 C, and various pressures respectively. Then I correlated those to what the ECM reported in raw decimal. Then I performed polynomial curve fits (from all those data points) to find the polynomial coefficients so I calculate the temperature in C (or pressure in mmHg) directly from the raw decimal value. I still have the curves for the CTS, the IAT Sensor, and the MAP Sensor. Since the GUI does all the conversions for the user, I never showed these curves. But since they may help users in diagnostics and testing these sensors, I am going to add these curve graphs to the GUI so you can see each sensor in: temperature/pressure vs. resistance vs. voltage vs. ADC raw value vs. units in F or C/inHg or mmHg.