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ted von Kampen

This may be a stupid question but here goes. I have noticed the earlier 924 distributor used a magnetic reluctor that had 4 tangs sticking out. Presumably that gave each of the 4 cyl ignition pulses. Logical. However, my 1981 has the TCI-H Hall effect style of system. If this is for a 4 cylinder engine why does the metal ring that passes through the hall effect generator have 5 slots instead of 4? Does not make sense. There is no PN on it so I have no way to check. Maybe one of the forum members is an expert on Bosch ignitions and can explain it.
Thanks
Ted

Fifty50Plus · Posted: Thu Feb 02, 2017 5:09 am Post subject:

Someone put an Audi engine in your car?
_________________
1979 924 NA race car H-Prod SCCA
1982 924 NA race car - Sold
1981 924 Turbo sold
1982 924 Turbo sold
1972 911 E race car - traded for Cayenne Diesel
1975 914 1.8 Building for H-Prod SCCA

ted von Kampen · Posted: Thu Feb 02, 2017 10:44 am Post subject: 924 Hall ignition 1981 Porsche

The engine in the car is definitely a Porsche 924 and the distributor has the correct PN also. The Hall sensor and the trigger wheel look new while the rest of the distributor look its age. This made me wonder what was going on.
I did some investigation today and found out that the 1981 VW rabbit 1.7 uses a similar distributor and TI-H ignition. However, the picture shown at NAPA clearly showed a 4 slot trigger wheel while mine is a 5 slot. I suspect someone put a AUDI 5 cyl trigger wheel in this distributor. It has had a lot of misfires and backfires in the intake as well as exhaust. Using a timing light strobe, the misfires on #3 were accompanied by a non-flash on the light when hooked to ignition wire #3. Also when cranking I would get kickbacks. It never ran good and I just could not get the timing to set.

I suspect this trigger wheel has been the whole problem for 2 months. Now to find a 4 slot wheel. Do you know of any used 924 TI-H distributor or VW distributor I can salvage a trigger wheel from. Your comment seems right on as I know Audi made a 5 cyl car and they used the Bosch system.

Let me know if you have a clue where to find the 4 slot trigger wheel.
Thanks,
Ted

ideola · Joined: 01 Oct 2004 Posts: 15550 Location: Spring Lake MI

Recommended reading:
http://www.924board.org/viewtopic.php?t=40844
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erstwhile owner of just about every 924 variant ever made

ted von Kampen · Posted: Wed Feb 08, 2017 11:07 am Post subject: Problem solved

As I suspected the 5 slot trigger wheel was the culprit. It needs a 4 slot trigger wheel so got one for a 1981 VW rabbit 1.7L and it works perfect. What a ridiculous hidden problem. The 5 slot must have been for a 5cyl Audi or similar. How it got in the distributor is beyond me. But the car sat for 15 yrs. Anyway it now runs correctly.
Thanks for comments guys.
Ted

ideola · Joined: 01 Oct 2004 Posts: 15550 Location: Spring Lake MI

Yeah, that is definitely one for the Previous Owner Hall of Shame.

Awesome news that you found a solution.

_________________
erstwhile owner of just about every 924 variant ever made