Bad IAP Sensor?

[65Cobra]

After months of trying to adjust the PCIII map in order to get the bike running, it now seems like the IAP Sensor is bad. I performed some tests per the service manual but could use some input...

With coupler disconnected and Ignition ON...
Voltage between Red Wire and Ground on coupler was 4.93v
Voltage between Red Wire and B/Br Wire on coupler was 4.87v
The manual was fairly clear on this and said each of these should read 4.5v-5.5v so both the wiring and connections seem to be fine.

Next, I removed the IAP Sensor and took it upstairs to test. I powered the sensor using (3) new 1.5v batteries wired in series (4.5v total) then checked the voltage between Vout and Ground... it was 3.25v. But the manual doesn't say in that section what the reading should be. However, further down the page it says "Output voltage (Vcc voltage 4.5 - 5.0 V, ambient temp. 20 - 30'C, 68 - 86'F)" which I think is the reading I should have measured.

I decided to connect a Vacuum Pump/Gauge to the IAP Sensor and checked the voltage under vacuum. As I changed the vacuum, the voltage did change, but the readings were all lower than what's listed in the manual...

Voltage between Vout and Ground at 80kPa was 1.00v
Manual says the range 76-85kPa should be 2.6v-3.1v
Voltage between Vout and Ground at 70kPa was 1.28v
Manual says the range 70-76kPa should be 2.4v-2.9v

I wanted to see if anyone commented before I dish out $100+ dollars for a new sensor. Or maybe someone here has an IAP sensor at a better price?

Thanks

Dave

 

[65Cobra]

I was told elsewhere to test the AP Sensor for comparison purposes since both sensors have the same curve. So I did and the results were exactly the same. Again I couldn't get the vacuum pump to go over 83 kPa but I tested from 80 kPa down to 30 kPa and all voltages were identical between the IAP and AP Sensors:

Vout to Ground at 00kPa was 3.26v (Manual: 4.5v-5.0v)
Vout to Ground at 80kPa was 1.00v (Manual: ~2.8v)
Vout to Ground at 70kPa was 1.28v (Manual: ~2.4v)
Vout to Ground at 60kPa was 1.56v
Vout to Ground at 50kPa was 1.85v
Vout to Ground at 40kPa was 2.14v
Vout to Ground at 30kPa was 2.42v

I'm told that means my IAP Sensor is good... which is good news (except now I'm back at square one... again). But I don't understand why my voltage readings are so much lower than those listed in the manual, so if anyone has an explanation I would really be interested in knowing.

Thanks

Dave