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[Rockhampton]

Hi all,
Just had the crank sensor replaced as my miggy finally threw the code up and would not start when warm. Since I've had it changed, I've noticed the following, and I was wondering if one of you guys could let me know if it is just coincidence....
1) The fuel economy has improved according to the MID (but not driven enough to calculate if it really has yet)
2) The sticking rev counter does not seem to stick any more
3) The autobox seems to be changing smoother.
I understand what the crank sensor is for and how it works, but I don't know what the ECU does with the signal (apart from control the fuel and sparks)
Just out of interest really! 

[RobG]

 It generates a signal that the ECU needs to determine the position of the crankshaft and the number-one cylinder. This info controls ignition timing and the operation of the fuel injectors. The signal from the crank sensor also tells the ECU how fast the engine is running (engine rpm) so ignition timing can be advanced or retarded as needed

[Gaffers]

So would a faulty crank sensor affect auto gearbox operation?

[Debs.]

So would a faulty crank sensor affect auto gearbox operation?

It did when my sensor became cranky: perhaps it`s the change in torque output, but until I changed for a new crank sensor, the gearbox always seemed to be lingering in the wrong gear. :-/

[RobG]

It has been known. Been posted here a few times about members having autobox probs & symptons have gone when sensor renewed

[Gaffers]

It might be worth the investment then 

Arent they about £35 on TC?

[Rockhampton]

Well, it certainly has improved the driving experience of my car - I had trouble with it hanging around in first and third occasionally, but that has completely vanished. I don't know enough about how the ECU's work, but I figure that the transmission controller would need to know how fast the engine was going as well as the speed of the wheels in order to make a correct decision as to when to change - the old supply and demand thing..... just wondered if any knowlegeable members could confirm or deny!