MisterD
Registered User
Doing some tests with the VAG-COM. I'm trying to find reasons for some poor performance and misfires I have been suffering, along with poor fuel consumption (27MPG average).
Anyway, I have monitored the voltage output of the knock sensors and found a strange phenomenon.
When I let the car idle 'til it's warm (I know I shouldn't really but it was for a test), it ticks over nice and smooth and the knock sensor readings are all very similar. However, when I drive the car to warm it up and repeat the test, the knock sensor for cylinder 1 & 2 shows a voltage rise of approx. 0.4 to 0.5 volts, and the engine is not smooth - in fact it seems to 'chug'.
If the sensor is faulty, surely the difference would be apparent all the time? Why should it change after driving the car? Could it be vibration?
Question based on the above: Would noisy valve gear have an effect on the knock sensor readings? I know that one cause for knock ****** problems can be loose ancillaries, so do valves count on this score?
Thanks in advance all you tech-heads /ubbthreads/images/graemlins/wink.gif
Anyway, I have monitored the voltage output of the knock sensors and found a strange phenomenon.
When I let the car idle 'til it's warm (I know I shouldn't really but it was for a test), it ticks over nice and smooth and the knock sensor readings are all very similar. However, when I drive the car to warm it up and repeat the test, the knock sensor for cylinder 1 & 2 shows a voltage rise of approx. 0.4 to 0.5 volts, and the engine is not smooth - in fact it seems to 'chug'.
If the sensor is faulty, surely the difference would be apparent all the time? Why should it change after driving the car? Could it be vibration?
Question based on the above: Would noisy valve gear have an effect on the knock sensor readings? I know that one cause for knock ****** problems can be loose ancillaries, so do valves count on this score?
Thanks in advance all you tech-heads /ubbthreads/images/graemlins/wink.gif