V50 Cruise control issue

[dukeyfilm]

Hi all, I'm having a strange intermittent issue with the cruise control on my 2010 1.6 diesel V50.
The cruise control engages correctly and I can set a speed, but if I then go to increase the speed say in 5th gear from 65mph to 70mph by pressing on the '+' , the revs will rise say 1.8k to 2k, or 2k to 2.2k, but then drop and the cruise will disengage. The cruise lights stays on the dash but the cruise 'on' display goes off.
This only happens when I go to increase the speed. It will also happen in other gears. Usually it is when the engine is working hard , going up hill for example but also I have noticed when cruising along a flat section of the motorway. It does this intermittently. I can increase speed via the accelerator pedal and then set the new higher speed with the '+' button.
Also today I was in 5th gear doing 70 on the motorway (cruise control not engaged) I went to accelerate and the revs rose and the 'change up ' arrow came on even though it has a 5 speed gear box. . Originally I thought this might have been the clutch slipping but I tested this by putting the car in 3rd and trying to pull away and the car stalls.

Any ideas? Could it be ECU or throttle body? Sensor issue?
Cheers.

[rxtian]

If the revs are rising but the car is not getting faster at the same rate it pretty much has to be the something in the driveline slipping - the clutch is your best option tbh.

I'm assuming the RPM guage rising aligns with the engine note.

[dukeyfilm]

Thanks for your reply rxtian. The car seems to accelerate in line with the revs but then when the revs increase by about 200 to 400 rmp the cruise comes off and the revs drop. Almost like a rev limiter. But when using the accelerator pedal the speed and revs are in line and will continue to rise as normal.
As I said I tested for clutch slippage by putting the car in third and tried pulling away from stationary and the car stalls. So it seems not to be a clutch problem.

[IainG]

Hi
The clutch on my V50 2.0D started slipping. But only when in 4 th or 5th when going up a hill. Only ever when over about 65. Couldn't get it to slip when pulling away in a high gear. It is something to do with the torque or power band
The clutch was actually just down to the rivets.
Wonder if the cruise control system is picking up the revs rising but the speed not following? And then disengaging?

Worth checking under load up a reasonable hill

Iain

[lockstock]

Originally Posted by dukeyfilm

Thanks for your reply rxtian. The car seems to accelerate in line with the revs but then when the revs increase by about 200 to 400 rmp the cruise comes off and the revs drop. Almost like a rev limiter. But when using the accelerator pedal the speed and revs are in line and will continue to rise as normal.
As I said I tested for clutch slippage by putting the car in third and tried pulling away from stationary and the car stalls. So it seems not to be a clutch problem.

yr testing for a worn clutch wrong. Drive up to 30mph. Change up to 5th and floor it. If the revs go out of line with speed, the clutch is slipping. The other possibility is something up with the electronic throttle body. could try giving it a clean. disconnect battery first though, dont want to lose a finger!.

[V8XCV]

My guess would be If the revs are rising out of line with the speed the clutch will be slipping. The cruise control works by comparing the road speed to engine revs and if the revs increase but the speed does it it will assume you are trying to drive in slippy conditions and will disengage for safety (thinking you are on snow or ice).