If I set my cruise control to say 50, on a slight uphill incline every few seconds when the speed drops slightly, it goes from 1800ish to 3000rpm, and revs right up until it hits the right speed again, but feels very erratic at times

Just wondering if this was normal behaviour on a TD6? As I've said on here before I'm paranoid about gearbox/tc problems so every little thing I notice worries me!

Thanks in advance! 

it does rev to get the vehicle up to selected cruise speed but not sure it should be as harsh as you're experiencing.. ... - .- -.




Y. O. L. O.
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Thanks for the reply Stan. I'll try and get a video later on my trusty go pro!

Next step, what could it be?! 

At 50 you are in the muddly mix of 4th gear and 5th gear, along with torque convertor lock up territory.

Try just driving the same stretch of road at 50 and I guess much the same will happen. I often find the gearbox will hold to high revs in 4th between 50 and 60-65 and have to lift off slightly to get it to drop into 5th.

Maybe 55 would be a better speed though if you are tugging something this might not be best, but then would suggest not using CC for this in any case? .
Experience is the only genuine knowledge, but as time passes, I have forgotten more than I can remember
Volvo V70 P2 2006 2.4 Petrol 170bhp Estate SE
MG Midget Mk1 1962

Previous: L322 Range Rover TDV8 3.6 2008; L322 Range Rover TD6 3.0 2002; P38A Range Rover V8 1999

Thanks for the reply there Joe.

You said try it at 50, what speed did you actually mean ;P I can give it a go!

Not towing or anything like that so no worries there  

Here is a video, I thought I was filming for like 30 seconds and realised it was on photo mode!

When the video starts its just dropping down, and you can see how quickly it does it again! 

Yep that's normal. Stay reassured. My first Ffrr was a TD6 and it really used to annoy me that it it did this but it's just the nature of the beast. She was perfect and 100% fault-free, even over 100,000 miles.

Now have a V8 petrol and it s is much more relaxed.

I'm not surprised it annoyed you!

A few time I've had a passenger ask if we are breaking down / running out of fuel!! 

As Joe said your right in the middle of all the bad bits for the gearbox, at 50 it's right at the upper limit of the 10% slippage to stop torque vibration, and the slightest touch of the throttle will disengage the TCC (lock up) and allow the engine to rev freely...... try it at 55.... it will be in total lock up at that speed and less likely to rev it's bits off  Yesterday I couldn't spell Engineer... Today I are one!
Inventor of the 'Guide-o-Matic automatic wheel alignment tool'
Former long term L322 owner, Up/Down graded to a Classic Tractor!

At the risk of upsetting the 60+ brigade, I thought I would give this a try on the way home, on a 5 mile stretch of A road with plenty of ups and downs, a couple of steeper ones too.

Locked in at 50 on the CC, at 1800 revs, and to my surprise it just stayed there, didn't budge an inch all the way. Maybe my "hills" weren't steep enough or long enough to provoke the kickdown? I will have to take a trip out to Stockbridge where we have some real up and downers. .
Experience is the only genuine knowledge, but as time passes, I have forgotten more than I can remember
Volvo V70 P2 2006 2.4 Petrol 170bhp Estate SE
MG Midget Mk1 1962

Previous: L322 Range Rover TDV8 3.6 2008; L322 Range Rover TD6 3.0 2002; P38A Range Rover V8 1999

Interesting!

I haven't been that way yet, although will in the next hour or so on my way back home from work but going the opposite way up the hill (hill works up to motorway bridge both sides) I tried 55mph this morning, and it just sat there, now like you Joe I'm not sure whether it's as steep as the other side so will wait until traffic clears and try the original way! - if that even makes sense! 

my td6 has started doing this but doesnt rev more than a couple of hundred ,it does it when not in cc ,have i got a prob with it it says in the hand book press button to switch on light on dash comes on press again to suspend,then press and hold until light goes out to switch of. the prob i have is when i hold to switch off the light does not go out,has anybody got any ideas to what is wrong,thanks for a great forum.

Are you talking about the cruise contol?

I've never read the book regarding it, but I press the I / O switch to turn it on, set my speed, then press it again to cancel. If then pressed again it switches off the system completely... Maybe I've been doing it wrong 

It's all to do with the speed that your travelling at and the power available from the engine, if the ECU's determine that the engine doesn't have enough power to maintain the speed set it will disengage the torque converter lock up, which adds power to a rough factor of 1.9 x, and if the car is still loosing speed it will select a lower gear.

At 1800 rpm your not quite in to the max power / torque of the engine, so the gearbox has to compensate  Yesterday I couldn't spell Engineer... Today I are one!
Inventor of the 'Guide-o-Matic automatic wheel alignment tool'
Former long term L322 owner, Up/Down graded to a Classic Tractor!

cowman wrote:

my td6 has started doing this but doesnt rev more than a couple of hundred ,it does it when not in cc ,have i got a prob with it it says in the hand book press button to switch on light on dash comes on press again to suspend,then press and hold until light goes out to switch of. the prob i have is when i hold to switch off the light does not go out,has anybody got any ideas to what is wrong,thanks for a great forum.

you should press the 1-0 button to get the light on the dash, then at the desired speed press the +, to suspend the CC press 1-0 once and the speedo symbol to resume..... to cancel you need to press the 1-0 twice if your cruising and once if your not cruising....... there is no press and hold  Yesterday I couldn't spell Engineer... Today I are one!
Inventor of the 'Guide-o-Matic automatic wheel alignment tool'
Former long term L322 owner, Up/Down graded to a Classic Tractor!