help help help whats goin on

[craig g]

just changed by battrey cos it was dead and now the rev counter is dipping down 450 then back up too 900 its goin nuts can any one tell me whats wrong it does settle but as soon as stop after movin its off again   

[New Duncan]

I gave instructions about changing batteries some time ago. De-powering can cause problems.

Use the blasted search button to check what you are doing before you do anything else.

I dont know your problem, could be a sensor not responding when powered-up, ECU playing up, cold start sensor device on the blink.

Hang in there, somebody here will know where you should look.

[craig g]

i had the AA come out and they cleared a low voltage error
its still doing it but not as bad ..
he mentioned the car may remap its self when driving at different speeds is that right

[GolfGL]

Ive had my battery in and out loads and  never had a problem. I know the vws have a learning ecu so disconnect it again neg, then pos, reconnect pos, then neg. Take it for a fast drive and see if it helps if not possible sensor/fuses and and expensive vw diagnosis. 

[craig g]

thanks guys but found the problem
had a new samco sport dump valve on a development trial because i used to work there
and for some reason it was leaking...
should of checked that first  :embarassed:  sorry