[16saabs]

crancase sensor has gone again(6months 2nd hand), although i have got a spare of another car, is it possible that a lpt(wife's car fitment) distributor could be fitted and the sensor wires connected, or is that not an option,because its a lot easier to replace a distributor, than to remove the crankbelts, pulley etc in such an awkward place

 

[Matthew]

So you want to use the distributor's Hall sensor instead of a crank sensor?

On which model of car has the crank sensor failed? AFAIK only the normally-aspirated 16v cars had crank sensors (for the EZK ignition system).

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[Rodentmaster]

Hi there,

The idea of using the distributor is a curious one. However, you would need to ensure the timing of the pulse is very close to that of what is provided from the crank sensor. This is may or may not be difficult. You would need to disable the EZK from acting, (ie, timing or phase corrections) while you set base timing. I'm not sure if just setting to 16 deg BTC at idle is accurate enough or if the EZK will try and chase and adapt.
If you were to install a distributor, you need to establish a reference timing point. The crank arrangement is a fixed timing setup and the EZK box is designed to work with the parameter of the being timing fixed and known, so to speak. The distributor position or alignment would have to be well within the window for the spark contacts as well as the trigger pulses for the changeover to be successful.

Good luck

Cheers

 

[Matthew]

The EZK's crank sensor is a toothed wheel that indicates the engine's position down to a few degrees - many (36?) pulses per second. Surely the distributor's Hall sensor provides just one pulse per second...?

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[cdaly]

Mine wasn't toothed. There's a sensor mounted to the oil pump cover plate and a rotor mounted to the pulley. The rotor fits into a slot in the sensor and has two cutouts, 180 degrees apart. Since the crankshaft rotates twice as fast as the camshaft, this corresponds to the 4-per rev breaks in the distributor's hall sensor. To properly set up a distributor in place of the crank sensor, it's necessary to do a few things:

1. Identify at what angle the existing hall sensor should trigger. This will be when either the leading or trailing edge of a rotor cutout passes through the slot. There's a reasonable chance that this is at TDC (0 degrees) but it could be significantly before (the EZK system retards up to 20(?) degrees BTDC). Now you've taken the crank pulley off to verify this.
2. Modify the hall sensor wiring to accomodate the distributor's connections.
3. Identify the angle at which the distributor must be for its hall sensor to trigger at the same point.
4. Disable the distributor's centrifugal advance and vacuum advance/retard mechanisms.

By stage 2 above, you've got the current (not working) hall sensor out and you're attending to the wiring. What's the odds that damaged wiring / connection is the cause of the problem in the first place. You stand a good chance of fixing it instead.

If you want to go the route of using a distributor, you should really replace the entire ignition system from distributor to ignition amplifier. What you'll end up with will be a system that is not as well tuned as the EZK system since a set-and-bolted-down distributor is giving the same timing to all cylinders (with advance/retard inputs) while the EZK system times each cylinder to best advantage all the time...

So, it's probably doable but not advisable.

 

[Rodentmaster]

...............

As with cdaly, the pulley I changed has two 'cut outs'.
This relates to the 4 pulse per cam revolution = 2 pulse per crank revolution.

I would guess that the number of pulses fed to the EZK box is simply due to the basic architecture of the ignition system, 1 pulse to fire one spark. It is essentially the same through out the time from '86 to '93/'94 with only minor changes and improvements along the way. The EZK is simply a electronic form of centrifugal advance with a knock sensor for feedback. It is only delaying or advancing the trigger point to the ignition amp. Sure, there will be more detail than that but I'm keeping it glossy.

A bit related,....... I was informed by a club member that the crank sensor was prone to regular failure in the '89 or '90 year chassis's....
Does anyone have information to back this up? The trait of the problem at the time was believed to be poor water immunity....?????? Does this sound right?

Cheers

 

[16saabs]

thanks for all the replies, ist matthew, the car is a 900s 1988 f reg. to the others, it was just a thought to change,as stated in first thread, that it is easier to change a failed distributor than a crankase sensor, but having change it, on friday, it checked it before i put everything else back(pulley belts) it still ran a little lumpy, so having a spare car handy i changed the amm worked better, put everything back, took it down the road, and it went like hell again, so when the last crankase sensor went the amm was replaced also but the car never seemed the same, now i've got my old car back as it was(yahooooooo) . thanks for your again for your thoughts/answers much appreciated alwyne