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Old 10-05-2017, 03:00 PM   #1
Wendo
 
Join Date: Aug 2017
Location: Florida
Posts: 21
Hello, decided to go with the Audi V8.
One problem.
Ran into a low mileage 04 belt timed BFM V8.
Very clean, worth some mods.
But, crankshaft sensor comes in from the Audi transmission.
Looked at after market trigger wheel kits.
I think only the man above could position the stock sensor into the Boxster trans.
Can anybody point out what I am missing here?
Thanks.
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Old 10-05-2017, 09:38 PM   #2
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Location: Oklahoma
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Quote:
Originally Posted by Wendo View Post
... But, crankshaft sensor comes in from the Audi transmission. ... Can anybody point out what I am missing here?
Thanks.
***Edit: Read my follow-up in the next post, it isn't quite as simple as i thought...***
I am familiar with the AUX, ABZ, ART, and AWN engines, but I think this applies to all the 4.2L V8 belt-driven engines. The crankshaft sensor is just a Hall effect sensor and it is connected into the engine harness. It mounts externally to the transmission just below the 9 o'clock position (Left side) and sits about 1/2 inch back from the mating surface. It picks up a gap (2 tooth space) in the flex-plate or flywheel.

Audi refers to the crankshaft sensor as G-28 "engine speed sender". The ECU reads the signal as roughly 66 degrees BTDC. As long as you have the sensor and flywheel positioned to give that signal 66-67 degrees before TDC it should work.

One solution is to make a template to mark your transmission, then drill a hole and fabricate a mount (One guy doing a v8 swap to an A4 used JB weld and it did fine.).

Another solution that should work is to use an existing mounting point on the 5-speed transmission. The mounting hole is 45 degrees up from the mount on the Audi automatic transmission (ZF 5HP24). Eight bolts hold the flywheel on. At TDC the gap is just short of the 6 o'clock position (on my 32 valve ABZ engine. 2:30 on my 40 valve engine). Mounting it rotated one bolt hole clockwise moves that gap 45 degrees. The ECU doen't care where the gap is in relation to the shaft. It just needs that signal ~66 BTDC. I have not actually verified this with precision instruments to measure the positions, but eyeballing it looks very close.

Here's the stock mounting of the sensor:
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Last edited by 78F350; 10-08-2017 at 07:38 AM.
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