vr sensor signal plots

steve_c · Post by **steve_c** » Sat Jul 26, 2008 3:14 pm

I have just taken some 'scope pictures of my VR sensor signals. I need to know if these are good enough to operate the EDIS module. Scope scale is on the pics but signal amplitude varies between just under 5 volts pk-pk to 10 volts pk-pk. This shows the slightly concentric nature of the pulley. This was at cold idle so about 1200rpm. The two traces are one for each VR sensor wire with respect to vehicle earth. I have been having trouble getting a stable timing mark using a timing strobe (see earlier threads). One pic shows one complete cycle (two 'missing tooth' events), another shows a detail of the signal, another shows the 'missing tooth' waveform.

One other interesting thing is that using my settable timing light the pulley appears to move 10 degrees (1 tooth) for a 40 degree change on the timing light! I think I'll just set it to zero and use the teeth to gauge the advance.

steve_c · Post by **steve_c** » Sat Jul 26, 2008 11:45 pm

I must be getting senile. Can't even read a scope properly. Amplitude is from around 10 volts to 20 volts pk-pk

Post by **brentp** » Sun Jul 27, 2008 5:28 pm

We are creating a new test bench, so I cannot immediately compare notes.

How centered is the wheel on your crankshaft? does the variation in sensor-wheel gap correspond to the pattern in your VR signal?

steve_c · Post by **steve_c** » Sun Jul 27, 2008 6:23 pm

I haven't checked the exact relationship between pulley and plots. There is some runnout of less than 0.5mm. It will have to be what it is as I will not be taking the pulley off again unless I have to pull the engine for some reason.

Despite all my initial problems and queries, I now have an operational system. I am getting a fairly stable 10 degree default timing and the system behaves as expected when the controller is connected up. I am currently bolting the controller down inside the car, finalising the wiring, and hope to be on the road this week.

Post by **brentp** » Sun Jul 27, 2008 6:30 pm

Great, Steve. Were you able to identify the cause of the stability problem?

steve_c · Post by **steve_c** » Sun Jul 27, 2008 9:14 pm

No I wasn't, and as an engineer, I find that very frustrating. Same with the software. It may have been sensor placement, but with the amplitude of the signals I measured there appears to be some headroom in the placement of the sensor. However I don't know what the design parameters that Ford used for the sensor interface. I'm just happy that I have an operational system. I just hope it is reliable. Time will tell.