Boilermaker

I just recieved my CANscan tool from Harrision R&D and was playing around with it. I have a question for you guys that know much more about this car and electronics than I do. I was recording throttle position sensor along with other reading and I found that no matter what gear or rpm, my throttle position sensor reading maxes out at 78%. My value at idle is always 12% Is there something weird about these values or is this typical. Any input would be appreicated.

Thanks,
Boilermaker

wankel8

I haven't had a chance to use my CanScan much yet. The attached jpeg shows values from my car with engine not running. If i get a chance I will try to see if my car responds like yours. Note that I have an automatic.

I want to find out exactly what the different parameters mean and what their values should be. I was thinking that if a set of "baseline" values could be recorded, then diagnosing a problem down the road may be easier.

dannobre

iTrader: (3)

It's the range for that variable. You can convert to a 1- 100 scale by using

(x-12)X1.5 where x= CANScan value

sco

It looks like "Throttle Position Sensor" is reporting the absolute throttle setting reported by the throttle position sensor (I don't know exactly which of the supported throttle settings the RX-8 supports that CanScan reports for this value, but I'm pretty sure I'm right). The RX-8 supports three TPS values:
Absolute Throttle Position
Relative Throttle Position
Commanded Throttle Position

For example, the theoretical readings for the TPS could be 0 to 5V. Your RX-8's TPS could report 1V at throttle closed and 4V at throttle fully open. This would equate to 20% reading for Absolute Throttle Positon at closed and 80% at open.

Relative Throttle Position may be what you're interested in. This is the throttle reading relative to the minimum and maximum values that are actually reported by the sensor. In the same example, 1V for fully closed would read 0% and 4V for fully open would read 100% for relative throttle position. IIRC my RX-8 has reported values as low as 2% for relative throttle when at idle.

Note that in wankel8's readings, the relative throttle matches the commanded throttle. This means that the throttle is set to the position that the PCM actually requested it to be set to.

Next time I fire the car up I'll get my min and max readings for absolute and relative throttle position and follow up. It's early here (12:30am) so I don't want to wake the house up at the moment.

Speed Racer

That is weird, mine ranges from 0 with the engine off, 3% at idle and 99-101% at wide open throttle.

smd3

Using VAG-COM on my VW I was able to recalibrate the drive by wire (dbw) system, it was a built in function of the ECU really, which was accessable using VAG-COM. Is this something that is possible with the Mazda ECU? Could it benefite from this recalibration from time to time? The VW seemed to benefit from it, although it could have been placebo effect. I'm also assuming the ECU will do this on it's own from time to time.

dannobre

iTrader: (3)

On the CanScan there are more than one throttle position sensor reading. The raw data is the 12-78 range one I think

Plumeau

Can some one direct me on how to test the pedal sensors and the TPS on the throttle body? I have a p2109 code I'm trying to trouble shoot. Got the pedal in my vise and using a battery and DVOM to check it - since I have no fancy OBD2. 2011 R3 with 120k on the odometer. Are the pedal sensors rheostats or induction position sensors?