The squeak directly following shut down was in fact from the active exhaust as when we pulled fuse 19 between the rear seats it stopped.

Does the active exhaust in the XKR increase power or is it just for sound? Kinda like the way is sounds now w/o the active exhaust even under power, as there's no more back pressure blow back noise now. I know in the XKRS's special "performance" active exhaust has an effect on power from what I've read but no idea about the regular R.

 

The ones that have swapped out the regular exhaust for the Mina say that they lose a little HP on the low end due to the reduction in back pressure. The exhaust column is not consistent is the reason given for this.

You could experiment and test this for yourself with the fuse out to see if your take off power is affected.

 

Thanks.

It felt less powerful after i pulled the fuse but I thought it might be in my head. I did read in a non official article that when the flaps are open, flow in addition to noise increases. I would love to read some published data from Jaguar on the AE to see if they state any power improvements. I know in the Porsche sport exhaust there is no gain in power.

 

I found this diagram on the XFR forum, don't know if it's the same as the XKR as its a passive system

Active Exhaust.

Also found this post done here; same issue but different result when fuse pulled???


02-13-2011, 06:56 PM
jallitt
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I was sitting in my garage yesterday looking at what data I can extract from the OBD-II port and while revving the engine I could hear the active exhaust valves squeaking as they opened and closed.

So I pulled fuse 19 - which stopped the squeaking. But it's quite rowdy driving it around like that. Mainly in 2nd gear under a bit of load. Which isn't necessarily a bad thing but I already have a bit of a reputation as a 40-something year old ASBO (I wonder what the XKR would look like in ASBO orange).

I might put it back in - but now I'll always be listening for that squeak from the valves.

 

Seems like there would be some kind of lubricant you could put on there that would last a while...graphite maybe, something Teflon based?

 

Thanks would probabky work well. At least I know now it's the active exhaust valves for certain an I'll let the dealer take care of it.