zl1kmn

her is the flywheel on AAH

zl1kmn

went to 12v.org , sensor reads every teeth....
Is the starter ring position important? How to recognise it? Should be at DTC, when installed?
Sensor bracket was not removed.

grayjay

Bently has a procedure that requires a couple of VW-Audi proprietary tools in order to set the speed sensor position. Basiclly it aligns the sensor directly over a valley between two teeth at TDC. However, I dont think there is actually and difference among the teeth and it is only reading speed, not reference position. I replaced my flywheel speed sensor after I messed with the bracket position but did not have the tools to set it properly and mine ran fine, maybe I just got lucky?

In addition to your flywheel speed sensor, have you verified that the crankshaft position sensor is working OK? It fits directly into the engine block, lower left side below the motor mount bracket and reads crankshaft position.

zl1kmn

Went to Audi dealer today. They said, even the position is not good, I should be able to read the RPM with VAG. They don't have the special tool needed, 3308. It means, thet is very rare that it is needed.
The another tood needed, is just for locking the piston in position, while 3308 has a theeth, and goes between two theeths of the flywheel. Flywheel bolts are offset, you cannot miss on that one.

I will now get an oscilloscope, and check the RPM signal from the sensor, while cranking.
Sensor must be 1.2mm from the flywheel. Maybe it is too far away... But I cannot imagine, how that could happen, that is suddenly too far. I havent touched the sensor, while dismantling.

Re crankshaft sensor, a measured the impedance, and seems to be fine. But will check that one as well, while cranking. Impedance should vary.

Crankshaft sensor plug is black, right? And it goes to black plug.
RPM sensor is white, goes to grey, right?

zl1kmn

can be one more thing....


I have replaced the timing belt, camshaft and crankshaft seals, etc...

Could it be, that I messed up the timing by 180 degrees? Would the car try to start like that?

zl1kmn

Timing was not good. Beginners mistake....

grayjay

That definitly would do it. Glad you got it fixed.

The bracket for the flywheel speed sensor does not have adjustment for distance between sensor to teeth, only for position placement of sensor around the flywheel. Only reason I can imagine the speed sensor alignment tool is needed is if the ECU needs the speed signal pulses it gets from the FW teeth in perfect alignment with the crank position reference sensor in order to correctly time the ignition.