Mk1_Oz
22nd July 2017, 10:13 AM
I have titled this thread as a gearbox noise as that is my suspicion but I could be wrong....
Symptoms:
At a constant speed and lightish throttle there is a rumble noise from the car. Others have explained it as driving on a cattle grid maybe. As I am usually driving at the 60km/h speed limit this is where I notice it - engine speed 1200rpm, transmission in D, road speed 60km/h, constant throttle.
If I move the gear leaver into Sport the car drops down a gear, the engine rpm rise (1600 rpm) and the noise goes away.
If I apply a very slight amount of additional accelerator the noise goes away but then returns after a second or 2 once the car has settled to the adjusted speed (does not kick down).
I do not notice any noises at other speeds. Just seems to be low engine speed and lowish load. No other gearbox faults or symptoms.
My suspicion is that this is a torque convertor issue and most likely something to do with the lock-up clutch. I have looked at the RAVE files but it doesn't help me much. Think it implies I have a ZF 6HP26 gearbox.
Solution:
I could continue to push the stick into Sport mode when the noise happens.
I have a Nanocom and a Picoscope (oscilloscope) so want to try to do some diagnostic work. Can the Nanocom assist with looking at torque convertor and lock-up clutch data PIDs? Does anybody know where (and if) I can connect the scope to to get the required LUC readings?
Anybody had this issue before?
PS - I hate parts changing as a 'solution'. I like to know that something is definitely the cause before I spend big money changing parts!!
Symptoms:
At a constant speed and lightish throttle there is a rumble noise from the car. Others have explained it as driving on a cattle grid maybe. As I am usually driving at the 60km/h speed limit this is where I notice it - engine speed 1200rpm, transmission in D, road speed 60km/h, constant throttle.
If I move the gear leaver into Sport the car drops down a gear, the engine rpm rise (1600 rpm) and the noise goes away.
If I apply a very slight amount of additional accelerator the noise goes away but then returns after a second or 2 once the car has settled to the adjusted speed (does not kick down).
I do not notice any noises at other speeds. Just seems to be low engine speed and lowish load. No other gearbox faults or symptoms.
My suspicion is that this is a torque convertor issue and most likely something to do with the lock-up clutch. I have looked at the RAVE files but it doesn't help me much. Think it implies I have a ZF 6HP26 gearbox.
Solution:
I could continue to push the stick into Sport mode when the noise happens.
I have a Nanocom and a Picoscope (oscilloscope) so want to try to do some diagnostic work. Can the Nanocom assist with looking at torque convertor and lock-up clutch data PIDs? Does anybody know where (and if) I can connect the scope to to get the required LUC readings?
Anybody had this issue before?
PS - I hate parts changing as a 'solution'. I like to know that something is definitely the cause before I spend big money changing parts!!