Does everyone else's cruise control "pump" on and off? - Page 2

Nobby · 9th January 2018, 19:45

Definitely not right - could be a faulty sensor. Can't speak for the 75/ZT but I know that with some faulty ZF auto boxes you can get exactly this symptom where the gearbox Torque Converter is effectively slipping or the actuators are hunting causing the gears to shift down and then back into top. One of the experts on here will know - might need a T4 session too

Be interested in what the cause is - keep us updated

Jim Jamieson · 9th January 2018, 20:20

The cruise control when in normal operation should keep the car running at a nice smooth and steady speed.

The only complaint I have with the 75 cruise system is, when resuming from say around 60 mph to a memory speed of 70 mph the car goes to kick down and takes off with the engine screaming it’s head off.

I used to fit cruise control systems and the above instance should result in a smooth acceleration back to 70mph.

To compare, if driving manually and drop back to 60mph for traffic then accelerate back up to the 70mph limit the car would not go to kickdown.

I complained to MG Rover about this function back in 2002 soon after the purchase of our diesel Connoisseur.

Apart from this the switches are poorly positioned as you have to drop your hands down the wheel to operate cruise.
I have converted mine with an extra switch wired in parallel to the resume button. With this I can operate resume on/off without moving my hands from a “safe” driving position or taking my eyes off the road to find the correct switch.

beinet1 · 10th January 2018, 10:35

Mine are also "pulsating" I have never found the CC on my V6 comfortable to use, so have just skipped using it. On the other hand, its super smooth on my LR Freelander 2.

pletevl · 11th January 2018, 13:08

Quote:

Originally Posted by Jim Jamieson

The cruise control when in normal operation should keep the car running at a nice smooth and steady speed.

The only complaint I have with the 75 cruise system is, when resuming from say around 60 mph to a memory speed of 70 mph the car goes to kick down and takes off with the engine screaming it’s head off.

.

Thanks for that. Mine does exactely the same and I hate it, I don' use it any more.

Pete.

Lord of Hog · 11th January 2018, 13:18

Since roads aren't absolutely flat or friction free the car will always be looking to accelerate or decelerate in the absence of input from throttle or brake. The cruise can't apply the brakes so it simply stops accelerating. When the speed drops below what's set it has to accelerate again to bring the speed back up. The faster you've set it the less noticeable it is since it takes more throttle to maintain the higher speed. So at 70 the system needs to do very little whereas at 30 it needs to make constant adjustment. The CC on my 2.5 seems to behave exactly the same as they system on the Mitsubishis and Renaults I've had thus far. I suppose it all hinges on how noticeable it is under normal use.

wutang · 11th January 2018, 15:35

Cruise on the V6 is Via an arm that operates the throttle activated by a bellows type actuator and a vacuum pump, I would hazard a guess that those experiencing pulsing or hunting could have a slight leak in the system somewhere.

Car gets up to speed pump reduces vacume closing throttle to the desired position, slight leak allows air in to system closing throttle further, pump starts up and opens throttle so car accelerates back up to speed and round you go again.

Diesel cruise is all in the ECU and involves electronic witch craft, cant help there!

My V6 cruise was always rock solid.

Regards

Richard

ryszard · 11th January 2018, 16:24

Hi,I have cruise on both my launch car and my diesel,I certainly feel the cruise cutting in on the V6,although not pulsating but certainly noticeable when it activates, whereas on the diesel it is hardly noticeable,it is much smoother and relaxed,maybe due to the torque difference.Regards Ry...

Mike Trident · 11th January 2018, 22:34

My cruise is the best I have ever used. In my 75 manual CDTi with 160 remap it holds any speed you set it to and never flinches, mile after mile uphill, downhill, anywhere.

Mike24 · 11th January 2018, 22:43

I had a problem with the cruise control seeming to surge and then back off repeatedly. It turned out to be down to a crack in the plastic part of the intercooler where one of the hoses connects. I replaced the intercooler with a second-hand unit and the cc has been fine ever since.

9th January 2018, 19:45	#11
Nobby Aged to perfection! Rover 75 Conn SE Tourer Join Date: Nov 2006 Location: Princes Risborough Posts: 640 Thanks: 405 Thanked 423 Times in 226 Posts	Definitely not right - could be a faulty sensor. Can't speak for the 75/ZT but I know that with some faulty ZF auto boxes you can get exactly this symptom where the gearbox Torque Converter is effectively slipping or the actuators are hunting causing the gears to shift down and then back into top. One of the experts on here will know - might need a T4 session too Be interested in what the cause is - keep us updated __________________ Nobby....... Sometimes I talk to myself, Then we both LAUGH!

11th January 2018, 13:18	#15
Lord of Hog Gets stuck in Rover 75 2.5 V6 in Wedgwood Blue Join Date: Dec 2015 Location: Felbridge, East Grinstead Posts: 982 Thanks: 250 Thanked 294 Times in 206 Posts	Since roads aren't absolutely flat or friction free the car will always be looking to accelerate or decelerate in the absence of input from throttle or brake. The cruise can't apply the brakes so it simply stops accelerating. When the speed drops below what's set it has to accelerate again to bring the speed back up. The faster you've set it the less noticeable it is since it takes more throttle to maintain the higher speed. So at 70 the system needs to do very little whereas at 30 it needs to make constant adjustment. The CC on my 2.5 seems to behave exactly the same as they system on the Mitsubishis and Renaults I've had thus far. I suppose it all hinges on how noticeable it is under normal use. __________________ Conformity is not morality. Consensus is not truth.

11th January 2018, 22:34	#18
Mike Trident Posted a thing or two Rover 75 CDTi Saloon & Citroen C1 Join Date: Jun 2016 Location: Oakenshaw, Near Bradford Posts: 1,622 Thanks: 385 Thanked 552 Times in 328 Posts	My cruise is the best I have ever used. In my 75 manual CDTi with 160 remap it holds any speed you set it to and never flinches, mile after mile uphill, downhill, anywhere. __________________ Rover 75 2.0 CDTi (131Ps) Conn SE Saloon. (Manual) 160 Remap, cruise control, electric window blind, temp gauge, Real walnut / ZT interior, FBH with GSM control. BORN Tuesday, 5th October 2004 @ 12:35:52 This vehicle was the 104,679th 75 to run off the production line, out of 112,381 This vehicle was the 3,318th 75 CDT Connoisseur SE (135) to be made out of 4,744 This vehicle was the 12,440th 75 in Starlight Silver (code: MBB) to be made out of 14,280 Starlight Silver 75s

9th January 2018, 20:20	#12
Jim Jamieson This is my second home Rover less ! Join Date: Jun 2011 Location: Tarbolton Posts: 3,442 Thanks: 393 Thanked 888 Times in 542 Posts	The cruise control when in normal operation should keep the car running at a nice smooth and steady speed. The only complaint I have with the 75 cruise system is, when resuming from say around 60 mph to a memory speed of 70 mph the car goes to kick down and takes off with the engine screaming it’s head off. I used to fit cruise control systems and the above instance should result in a smooth acceleration back to 70mph. To compare, if driving manually and drop back to 60mph for traffic then accelerate back up to the 70mph limit the car would not go to kickdown. I complained to MG Rover about this function back in 2002 soon after the purchase of our diesel Connoisseur. Apart from this the switches are poorly positioned as you have to drop your hands down the wheel to operate cruise. I have converted mine with an extra switch wired in parallel to the resume button. With this I can operate resume on/off without moving my hands from a “safe” driving position or taking my eyes off the road to find the correct switch.

10th January 2018, 10:35	#13
beinet1 Posted a thing or two Rover 75 2.0 V6 Auto Join Date: May 2011 Location: Sandnes - Norway Posts: 1,560 Thanks: 64 Thanked 283 Times in 174 Posts	Mine are also "pulsating" I have never found the CC on my V6 comfortable to use, so have just skipped using it. On the other hand, its super smooth on my LR Freelander 2.

11th January 2018, 15:35	#16
wutang Posted a thing or two Rover 75 2.5 auto (LPG) & mg tf 160 Join Date: Nov 2006 Location: Dartford Posts: 1,124 Thanks: 5 Thanked 39 Times in 36 Posts	Cruise on the V6 is Via an arm that operates the throttle activated by a bellows type actuator and a vacuum pump, I would hazard a guess that those experiencing pulsing or hunting could have a slight leak in the system somewhere. Car gets up to speed pump reduces vacume closing throttle to the desired position, slight leak allows air in to system closing throttle further, pump starts up and opens throttle so car accelerates back up to speed and round you go again. Diesel cruise is all in the ECU and involves electronic witch craft, cant help there! My V6 cruise was always rock solid. Regards Richard

11th January 2018, 16:24	#17
ryszard Gets stuck in Moonstone diesel,X351 Jaguar and now MG ZT 260 Join Date: Dec 2013 Location: Northampton Posts: 682 Thanks: 288 Thanked 118 Times in 96 Posts	Hi,I have cruise on both my launch car and my diesel,I certainly feel the cruise cutting in on the V6,although not pulsating but certainly noticeable when it activates, whereas on the diesel it is hardly noticeable,it is much smoother and relaxed,maybe due to the torque difference.Regards Ry...

11th January 2018, 22:43	#19
Mike24 Loves to post Rover 75 CDTI Auto Saloon Connoisseur SE Join Date: Apr 2015 Location: Coventry Posts: 358 Thanks: 166 Thanked 67 Times in 56 Posts	I had a problem with the cruise control seeming to surge and then back off repeatedly. It turned out to be down to a crack in the plastic part of the intercooler where one of the hoses connects. I replaced the intercooler with a second-hand unit and the cc has been fine ever since.