Being told to shift up when In 5th gear

[Carbeepbop]

Hi all,

I’m driving a 07 Aurus with 198kmiles on the clock. Lately when i have been driving in fifth gear it’s been tell me to shift up but fifth gear is the highest gear. Also when i accelerate there is a surge in Revs but very little increase in speed/power. Any idea what might cause this. 
 

thanks

[Gray86]

The latter issue sounds like clutch slip, the issue with the shift up is a bit odd 

[jcps001]

Yeah, that does on mine too... I'm in fifth gear and the arrow up lights up... I don't bother with it. Also, sometimes when I'm stopped, the arrow down lights up... I really don't care about it.

I also agree about your clutch. You should check it.

[yossarian247]

I think the two problems may both be connected to the slipping clutch. ISTR with these manual gearboxes the car doesn't actually know which gear you have selected, it simply compares the engine RPM to the road speed and works out which gear you must be in. If the clutch is slipping slightly the revs will sometimes be higher than normal in relation to the road speed, so the ECU assumes you must be in a lower gear and lights up the 'Shift Up' indicator.

[jcps001]

The only use it may have would be to make you aware you're lugging the engine, as for the rest it is useless...

Just this past saturday, I was coasting on neutral to stop at a red traffic light, when the arrow down lights up... I don't bother or care.

[TonyHSD]

Yeap, even without any mechanical issues the shift indicator is something that simply ignored is the better choice. 👍

[yossarian247]

6 hours ago, jcps001 said:

The only use it may have would be to make you aware you're lugging the engine, as for the rest it is useless...

Just this past saturday, I was coasting on neutral to stop at a red traffic light, when the arrow down lights up... I don't bother or care.

Yes, it has no way of knowing if you're in neutral either. If the engine RPM is around idle but the car is still moving it assumes you must be in second gear (or higher) and labouring the engine!

[Cyker]

That's so bizarre! I assumed they had sensors in the gearbox!

Doing it that way is both very clever and really stupid at the same time  

[tavy]

  There's no sensor in the gear box, processor compares car speed, engine revs and this processor must know the car has 5 speed, so that the clock to not light "shift up" arrow when car is in 5th gear, but in Oisin's case processor appears doesn't know that the car has only 5 speeds.  Maybe the clocks are taken from a 1.3  6 gears Auris...

[yossarian247]

14 hours ago, Cyker said:

That's so bizarre! I assumed they had sensors in the gearbox!

Doing it that way is both very clever and really stupid at the same time  

It can lead to some bizarre effects, like telling you to change down when you're crawling to a stop in neutral, like Jose has found. There is a sort of method to its madness though, or a madness to its method perhaps!

[yossarian247]

4 hours ago, tavy said:

  There's no sensor in the gear box, processor compares car speed, engine revs and this processor must know the car has 5 speed, so that the clock to not light "shift up" arrow when car is in 5th gear, but in Oisin's case processor appears doesn't know that the car has only 5 speeds.  Maybe the clocks are taken from a 1.3  6 gears Auris...

In Oisin's case it's almost certainly due to the clutch slip. The gearbox is in 5th, but because the clutch is slipping the revs have risen to the level they would be in say 4th gear at that road speed, so the car thinks it must currently be in 4th and wants him to change up into 5th.

[Mooly]

Is it worth resetting the ECU (Battery disconnect) to see if it helps?

I notice on my 1.33 (which is 6speed) that the shift lights also depend on engine loading and in a strong headwind on the motorway I can sometimes get it to show that I should change down from 6th to 5th even when on the level.

In the OP's case there is no way that it should be able to display something that is non valid. 

As other have mentioned re the clutch, a manual gearbox should never be able to show a change in engine revs without the road speed increasing or decreasing as appropriate because the clutch should be firmly coupling the wheels to what is ultimately the crankshaft of the engine. They can not change speeds independently of each other with clutch let out and in gear.  

[yossarian247]

1 hour ago, Mooly said:

 

In the OP's case there is no way that it should be able to display something that is non valid. 

 

As far as the ECU is concerned, it is valid. The engine is over-revving due to a slipping clutch. As a result the ECU thinks the car is in a lower gear than it really is. Therefore due to the excessive revs it illuminates the 'Shift up' indicator, despite the car already being in the highest gear available. Fix the slipping clutch and the dash indicator should be fixed too. 

[Mooly]

OK, I suppose that's a valid argument 🙂

(I see the OP hasn't followed up with any more information)