924Board.org

[dwak]

On my '81/'82 931, my ignition module is fine, so I'm now testing my flywheel sensor for pulse. Do you know a good test? If that's good then the next target is the ignition control unit ($$$$$). It's an '81 US unit (Siemens 5WK1665) but the engine is ROW '82. I wonder if that's a conflict. The fuel systems powering up but I'm not getting a spark at the coil when we run the metal end of a screw driver over the sensor tip.
dwak

[John H]

To test the flywheel sensor you need to unplug from the digital control box.
Then connect a multimeter between the terminals on the plug to see if there is a complete circuit.

If you connect the centre terminal to each outside terminal (individually) there should be continuity. If not then the chances are the sensor is shagged. Also there should be a spacer between the sensor and the bellhousing. Have you looked at the module on the front left fender this is normal the unit that stops the car from running. The sensor’s them selves are pretty trouble free. However they have been known to be damaged by hamfisted mechanics when they have been reinstalling an engine after changing the clutch.

I assume you're still using the flywheel that came with the car as the flywheel has one tooth which is the reference tooth and without this nothing happens.

The difference in control box shouldn’t matter. The different boxes just run different ignition curves due to smog requirements. I’ve used a normal 931 in the GT and the GT in a normal 931 without any problems.

Have you looked at the module on the front left fender this is normal the unit that stops the car from running. If your module is shagged then the module from an early non digital can be used. Or in fact a vast majority of European cars use the same module e.g. Volvo 240/360/740/760, some Golf’s and Scirocco’s , Audi’s etc. So this module shouldn’t be hard or expensive to find.

[Zuffen]

John

what if any difference did you get when changing between the GT and 931 boxes.

Is there any performance gain other than redline?

_________________
Bob Dodd - 924turbo@cox.net
931 1982, 944 1982 euro, 924S 1988SE, 93 968 tip 06 Silver Cayenne S, 06 Black Cayenne S

I have Way too many cars, parts for the 931,944 and 951

[John H]

There was no real difference in the box it really only modifies the curve to suit the different boost characteristics of the GT turbo charger and the higher boost the GT runs.

I gatherin the mid to late 80's when the turbo's had misfires etc that were traced back to the control box the Porsche agent sin the UK used to retro fit the GT box. As th eGT had highter boost the curve had a bit more retarding in it and hence power dropped fractionaly in these cars but not noticable.

I'll hav eto dig out the curves for the GT box I used to have a hard copy somewhere and compare it with the normal 931.

[Zuffen]

What about the fuel distribtor, are we looking at greater fuel flow or still just a curve to the turbo map.

Is the gains in the ROW and GT based on higher boost and intercooling?

I'v ebeen trying to figure out what makes the power gains between the US and ROW models.

_________________
Bob Dodd - 924turbo@cox.net
931 1982, 944 1982 euro, 924S 1988SE, 93 968 tip 06 Silver Cayenne S, 06 Black Cayenne S

I have Way too many cars, parts for the 931,944 and 951

[dwak]

We did change the flywheel and clutch out of the '82 ROW engine, they being fried, and used the original '81 US clutch and flywheel which matched the cars original sensor anyway.
I bought a new ignition module (same #s but for an Audi 5000) but that made no dif.
We're a little suspicious of the control unit as the cover was loose and had been opened by someone earlier.
We'll try the sensor test. Otherwise I might have to steal the management system from the '79 931US parts cars, if that's feasable, (don't tell Rick, he owns half).
dwa

[John H]

[John H]

[John Brown]

Only way I know of to completey check the sensor (its a coil) is to check the output with a scope. Though if continuity is good there is not much else that can go wrong. As I have oft stated, an old used $20 Oscilloscope will work fine as the freqencies involved are actually quite low. You should see a nice sine wave.

John, do you know what the spec is for the spacing between the sensor and the teeth?

[dwak]

If I end up having to replace the dig. ignition control box and it's costly, is there a cost effective aftermarket upgrade for the electrical side engine management?

dwak

[John H]

[John Brown]

The sensor is, I think, about $100.

There is no cost effective way to do a lot of things on these old cars. The cost effective thing to do would be to buy a nice used Integra R. But that would not be so much fun!

[dwak]

There is a listing for a crank sensor for '81/'82 Porsche 924 Turbo in the Well's Electronic catalogue but the Canadian Tire Store I was in isn't allowed to sell Porsche parts.???? Some sort of wierd conspiracy!
John, you say $100US for that shtinking little part!!! Holy shmoley!
Oh well, I'm trying a few other avenues so don't leave your 931's unattended in a parking lot.

dwak the viking spawn

[dwak]

Finally got hold of a new flywheel sensor (the old one was baffed) via Horst Kroll in Toronto via a Porsche specialist in LA.
We installed it today and cranked up that Euro motor finally. The fuel pumps needed quite a bit of persuading but finally started pumping fuel after multi cranking and wetting.
Motor sounds good so far. Gradually reconnecting the 'hybrid'.
Those sensors are like hens teeth.
dwak