Help please - Speed pulse sensor

[lambo911]

Hi All,

My 964 won't start. It's not the DME relay as you can hear the pump and can smell fuel in the exhaust. There is no spark but there is 11.3v at the coil, which dips to about 8 when cranking but doesn't fluctuate.

I figured it was the pulse sensor so I've changed this for a new one and did the plug connector change.

Still won't start!

So I thought I should check the new connector continuity to see if a wire has come off inside.

The white wire is ok.
The shroud wire is ok, but it also has continuity through to the brown wire. I checked for stray wires between the two but can't see any.

So my question is... is the shroud wire and brown wire connected together somewhere else, are the both earth in which case the reading I'm getting is correct??

Help please as car is immobile.. and looking sad, as am I

[lambo911]

I found a wiring diagram and I think brown and the sheath are joined

[lambo911]

Can someone please confirm if I have the correct replacement mounting bracket.

The one on the car is the original one and is 964 101 187 1R (looks the same as 96410118700)

I was sent 964 101 187 02, which is different in design, so I am wondering if this is holding the sensor at the correct distance form the flywheel?

[Newsboy]

I believe that a bad flywheel speed sensor would prevent both spark and fuel from happening, so don't know why you smell fuel in exhaust? The distance to set the sensor for 89's(single mass flywheel)is
.08mm for 1990 and up is 1.0mm. You can test to see if your sensor is operating properly.
To test this, you open the DME relay(under driver's seat) and used a multimeter set to AC voltage, across pins 47 & 48 of the large plug. iT's supposed to read 3 volts. If it's 0, your sensor is hooked up incorrectly, or bad.

[lambo911]

Thank you for the reply.

I thought the DME relay was in the fusebox under the bonnet, is there another one under the seat?

Thanks
Richard

[Newsboy]

The DME relay is in the Frunk, Main control unit is under drivers seat.

[lambo911]

Disconnected the plug and measured the voltage, with ignition on and cranking. 0 volts so need to recheck the plug wiring I think.

[ischmitz]

Make sure you have the correct mounting bracket. There are two versions. One is for the '89 single-mass flywheel and the other for later dual-mass flywheels. It's not the spacing but the offset between teeth plane and engine case that makes them different.

Spacing between flywheel sensor and flywheel should be ~ 0.8mm. Some glue a penny to the sensor as a spacing guide.

Then you can measure flywheel sensor signal on the main DME plug on pin 47 and pin 48 with a voltmeter set to AC. Check for ~ 2V-3V during cranking.

If the DME sees the sensor signal during cranking it will turn on the fuel pump and needs to issue fuel and spark pulses. If one is present and the other is missing there is a fault either in the DME or downstream (e.g. igntior module)

Ingo

[lambo911]

Hi All, now sorted.

I had been given the wrong support bracket, I needed 964.101.187.01 but had been given 964.101.187.02

Also in my original post I asked if the shroud and brown wire were connected, the answer is yes they are, so both earths in effect.

Proper bracket now fitted and it is working perfectly!