The 0.8mm Sensor gap

[eddie224]

Hello all! How important is that 951 0.8mm sensor gap? What happens if you don't set it exactly? i.e. how would one know if it isn't set to 0.8mm?? Thank you.

[944 Ecology]

It needs to be close enough to generate a waveform strong enough for the DME/ECU to sense the timing. There is a waveform in the factory service manual you can compare the waveform to.

It is fairly critical, too close and there is a chance of physical damage... too far and the signal is not strong enough.

[eddie224]

First, thank you for your reply. Let me be a bit more specific. If the gap was incorrect, would the engine try to start, start and run poorly, or anything other than crank? Tx

[944 Ecology]

It depends... it may start and run poorly, or it may not start at all, or it may run poorly at high speed.

[grendiers]

I replaced sensors on a 924S years ago. It was easy as the bell housing was pretty dirty. As when I removed bracket, there was a nice outline remaining. I just installed it in the same place. Haven’t ever looked at the setup on my 951 to see if it’s the same.

[soxnail]

You can back the sensor of, then with (a strong battery) look at the signal on a scope crank car, look at signal compare the the pic below. Screw the sensor in a little at a time repeating the crank look process till it looks to have the same amplitude as the pic. Scale is 0.5V per division.
Sox

[944 Ecology]

Originally Posted by soxnail

You can back the sensor of, then with (a strong battery) look at the signal on a scope crank car, look at signal compare the the pic below. Screw the sensor in a little at a time repeating the crank look process till it looks to have the same amplitude as the pic. Scale is 0.5V per division.
Sox

Good idea, if you have an oscilloscope. My experience is that 944 owners, in general, do not want to spend an extra dollar on tools if they can avoid it.