Stepspeed problem

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panda47
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Joined: Sun Jun 11, 2017 8:27 am
MGF Register Region: Elsewhere

Stepspeed problem

Post by panda47 » Sun Jun 11, 2017 8:38 am

Hi all
I have a 2003 stepspeed TF that recently has a mind of its own with the gearbox
When I'm driving it will suddenly change down to 1st gear which is quite scary.
I've replaced the airflow sensor and cleaned the contacts that feed into it,but still have the same problem.
Usually only does it once or twice then all is ok.
Has the correct oil in it.
Any ideas very much appreciated.

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talkingcars
Posts: 5766
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MGF Register Region: South East
Model of Car: mk1 VVC
Location: West Sussex
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Re: Stepspeed problem

Post by talkingcars » Sun Jun 11, 2017 8:45 pm

Hi and welcome to the forum

When was the last time the oil was changed?

James
Home to black Alfa 159 3.2 V6 Q4, blue MGZR160, green MGF VVC and grey MGF 1.8i, and red MG Maestro T16.

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Tipper
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Model of Car: RV8 + ZS180
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Re: Stepspeed problem

Post by Tipper » Mon Jun 12, 2017 10:16 am

Electrical problems sometimes affect the CVT gearbox usually corrosion of plug contacts.

There are switch contacts below the gear lever that may need cleaning and a multi-plug that connects to the front face of the gearbox low down - this is a favourite damp/corrosion spot. In addition the gearbox ECU is located behind the boot carpet inside the left rear wing. check these connections are secure.

The gearbox drops the ratio in response to throttle position and braking. Does the gearbox work in 'manual' mode?

Oh and what airflow sensor? I didn't know there was one, just a throttle position sensor but that won't affect the gearbox operation AFAIK.

You'll also find that auto gearbox 'specialists' know nothing about these cars' CVT boxes so don't bother talking to them!

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