Vauxhall Astra - 5th gear questio

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Sat 23 Jan 2021 16:14
Vauxhall Astra - 5th gear questio - Luke Armitage
Apologise if in wrong thread

Car:Vauxhall Astra 2010 (diesel, 6 gears)

Ive just bought the car and noticed when i put it into 5th and let the speed decline on its own or if i brake and end up at 30mph the car will try and speed its self back up to 40 without me touching the pedals. Is this normal?

Every other gear seems to work fine, cruise controll is off 100% the car just trys to speed its self up. Only seems to speed up to 40mph.

Thanks
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Sat 23 Jan 2021 16:21
Vauxhall Astra - 5th gear questio - skidpan

Possibly the antistall?

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Sat 23 Jan 2021 16:33
Vauxhall Astra - 5th gear questio - Luke Armitage
See i know nothing about cars but thats the first thing i thought off. The car trying to prevent itself stalling. Didnt know that was a thing
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Sat 23 Jan 2021 19:41
Vauxhall Astra - 5th gear questio - bathtub tom

Diesels have tremendous torque, I suspect what you are experiencing is the engine dropping to tickover revs.

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Sat 23 Jan 2021 20:11
Vauxhall Astra - 5th gear questio - Luke Armitage
So this isnt something to be too worried about no? Ill just have to gear up and down better than i did in my previous petrol car
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Sat 23 Jan 2021 22:47
Vauxhall Astra - 5th gear questio - bathtub tom

What age is the car? I thought an EU directive required all cars to have 'nag' lights that told you when to change up and down.

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Sat 23 Jan 2021 23:04
Vauxhall Astra - 5th gear questio - Andrew-T

Diesels have tremendous torque, I suspect what you are experiencing is the engine dropping to tickover revs.

If this is a 6-gear box, 40mph seems high for idling in 5th. My diesel will trundle happily in top down a gentle slope, doing about 1100 rpm at 30mph. True idle is around 800, so settling to 40mph doesn't ring true. Not cruise control, is it ?

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Sat 23 Jan 2021 23:25
Vauxhall Astra - 5th gear questio - Luke Armitage
Ive definitely not got cruise controll on. Thats the first thing i thought it would be
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Sun 24 Jan 2021 09:22
Vauxhall Astra - 5th gear questio - Andrew-T
Ive definitely not got cruise controll on. Thats the first thing i thought it would be

What is on the rev-counter when this happens ? At a true idle I would guess it should be somewhere below 1000.

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Sun 24 Jan 2021 10:31
Vauxhall Astra - 5th gear questio - Bolt
Ive definitely not got cruise controll on. Thats the first thing i thought it would be

What is on the rev-counter when this happens ? At a true idle I would guess it should be somewhere below 1000.

My old Diesel Civic if you went down to too low revs it would rev itself to higher speed rather than labour, some say it shouldn`t do it but Honda said it was to prevent engine labouring too much as it was designed to rev like the petrol.

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Mon 25 Jan 2021 16:55
Vauxhall Astra - 5th gear questio - skidpan

Ive just bought the car and noticed when i put it into 5th and let the speed decline on its own or if i brake and end up at 30mph the car will try and speed its self back up to 40 without me touching the pedals. Is this normal?

Been thinking a bit more about this over the past couple of days.

This is based on our experiences with a Kia Ceed 1.6 CRDi, the only 1600 6 speed diesel we owned.

The car would in no way drive at 30 mph in 5th, it would have been shaking itself to pieces. 30 mph in 5th would probably have equated to about about 1000 to 1100 rpm at which speed the antistall would definitely have added fuel and speeded the car up to about 40 mph. Even at that speed a sympathetic driver would never have continued to abuse the car, on a level road about 45 mph was required before it was happy in 5th.

I would suggest that its the way its being driven rather than a fault that is causing the "odd" symptoms. Use the gears, its what they are for.

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