Can anyone tell me what this does?

[Babybadger]

Can anyone tell me what this does? And does it affect how the autobox changes gear etc. Would my 95 855 (pre OBD2) have one of these and what are the symptoms of them going wrong?

http://www.partsforvolvosonline.com/product_info.php?products_id=4122

[iGGy]

You will have one of those and it’s mounted on the throttle body. It sends the current position of the throttle butterfly (which is also directly relative to the position of the accelerator pedal) to the ECU and it uses the position in conjunction with the other sensors to manage the fuelling and ignition.

A dodgy sensor could give it signals which could confuse the control units and cause the gearbox to act unpredictably. But at £40, it's a bit of an expensive thing to just try out. Have you checked your codes from the two diagnostic boxes behind the front OS headlight?

[Babybadger]

You will have one of those and it’s mounted on the throttle body. It sends the current position of the throttle butterfly (which is also directly relative to the position of the accelerator pedal) to the ECU and it uses the position in conjunction with the other sensors to manage the fuelling and ignition.

A dodgy sensor could give it signals which could confuse the control units and cause the gearbox to act unpredictably. But at £40, it's a bit of an expensive thing to just try out. Have you checked your codes from the two diagnostic boxes behind the front OS headlight?

The reason is that I posted this thread (http://www.vpcuk.org/forums/t12393-notchy-autobox-change-at-slow-speedhead-scratching.html) and have been looking at possible causes........

[blackbooty]

replaced mine recently, she ran like a dog, hunting for revs, stalling, bouncing revs.

aok as soon as replaced.

wayne