Crank Speed Sensor

[stealth_pug 0]

The crank speed sensor on top of the gearbox, how important is it? Does it affect the running of the car?

 

ta

[Tom Fenton 1,548]

What engine?

[stealth_pug 0]

1.9 running a 1.6 box

[simonb 0]

Do you know if this is Jetronic or Motronic?

[welshpug 1,666]

does it have a distributor?

[simonb 0]

Both variants have a distributor but the advance is controlled by the ECU with the later Motronic system and so rotating the dizzy will make no difference I believe.

[Tom Fenton 1,548]

The Motronic uses a coilpack buddy, no distributor.

 

If its a Jetronic the crank sensor does bugger all, if it is a Motronic then the crank sensor is needed for the engine to run.

[cybernck 403 1 Cars]

^ nope... on a 205 GTI and 405 Mi16, Motronic ECU still uses a distributor

(well a cap and an arm) but only to distribute the power to the spark plugs,

while the ignition timing itself is controlled by the ECU.

 

anyway, if it's there and it's plugged into the loom, then you DO need it .

[Hilgie 16 2 Cars]

The engine won't run without it.

[maiklas 0]

As written in CAPS software, crank angle sensor have three contacts:

1. output voltage

2. CAS return

3. screen wire

 

Resistance between 1 and 2 contacts should be 600 to 1600 ohms

 

 

I've measured resistance between 1 and 2 contacts and found 520 ohms. While cranking engine, resistance regularly peaked to 1500 ohms and drops back to 520. Does it mean that sensor is OK and ECU should get signal, or should it be measured output voltage too? I'm not sure, I've done it correctly, while found only 0,1v on No.1 contact, and in CAPS is written that while cranking there should be 1,4v RMS. I connected one multimeter's needle to CAS 1 and other to vehicles ground.

Well, my 1.9 gti motronic after engine change have no spark and no fuel in injectors. Thought CAS is fault, but replaced it with good one and nothing changed, no spark. From ECU goes 101 wire to amplifier and when I give +12 to that wire, coil gives a spark, so I think problem could be with ECU or with CAS (which replaced from running car). I’ve measured CAS gap to flywheel and there was less than 1 mm as it should be. What else could be fault?

[welshpug 1,666]

crikey, and old one!!!

 

if the CAS/TDc sensor is known to be good you need to check the wiring loom.