Engine: V8: "Slow Down or Shift Up" Message

[Hedge133]

I recently picked up a 2006 XC90 V8 with 96k Miles. Shortly after the purchase, the Check Engine Light appeared and the message, "Slow Down or Shift Up" displayed. I saw another post similar to this back from 2011 and it was diagnosed as a faulty Coil Wire. I scanned the XC and it showed "Cylinder 5,6 Misfire. My thought was coils.

Just curious if anyone else has dealt with this issue in the past and possibly point me in the right direction. Any help with this would be appreciated.

[Hedge133]

This is my first post on this site. Did I post it properly? Is it in the wrong section or area? Or has no one ever seen this message before?

[gmonag]

Sorry for not replying but most on here have the D5 diesel. I am not familiar with the V8, especially not the US version.

Anyone?

[john langrick]

Hi, as above. I believe your engine was produced by Yamaha for volvo. I also assume that it came with its own engine management software components to cater for a more complex engine.

The common petrol engine in most countries I believe is the t6 which (I think) is produced by volvo. Most xc90 I guess are diesel, they certainly are in the UK, there are a few v8 petrol but much rarer (and sought after).

Hopefully someone with v8 experience may be able to help but the rest of us can only read with interest but let us know how things progress.

John l

[Moose Test]

Yes it is a Volvo designed but Yamaha built engine and so yes, it will be using a different version of the engine management software to the other models but that should make no difference. At the end of the day, it's a petrol engine reporting a misfire on a couple of cylinders and I'd approach it in exactly the same way as any other petrol engine doing the same.

Firstly, I'd use the Volvo VIDA tool to read the fault codes. Reading these forums has shown that sometimes more generic scan tools provide error codes that don't exactly correspond to the actual Volvo hardware / software. It's good to have the exact fault code and description on hand before starting.

Assuming that it is a misfire, I'd pull the plugs affected and check their state (e.g. burnt electrode, oil contamination etc.). I'd also check that the coil pack (plugged directly into the top of the plug) looks ok (seated ok, no cracks, water or oil) and same with the wiring connector from the loom to the coil packs.

Once that's done, reset the error codes, take it out for a spin and read again. If there is still a misfire, suspect bad plugs then faulty coils packs first, unless additional fault codes from VIDA say otherwise (e.g. I think I'm right in saying that I have read on this forum that a faulty TDC sensor has caused misfire warnings on other owner's vehicles).

You might find this video on plug replacement useful: https://www.youtube.com/watch?v=cSSjwAKNsHc