Thats so strange been thinking about the same thing today too! Over the weekend went for a drive to Warick and coming off a roundabout on a dual carriage way overtook a slower car using the outside lane, looked in the rear view to see a newish XJ up my chuff and I was way past VTEC in 3nd about to upshift. I moved across to let the Jag past..........green flash on the badge saying XJR. Dont get me wrong the pace of the S is swift but the sensation of speed does diminish the longer you own it I think, but speed isnt everything theres alot more to enjoy about the car..........just think of the sunny weather!

Forgot to say air box lid is off but I wouldnt go as far as saying it murders performance.

 

Yeah, you are right. The event I described wasn't undertaken with another member of this board. I made up that I noticed a considerable drop in performance with the lid off and I completely fabricate all my 1/4er mile times in various states of tune. I also have zero knowledge of russells actual car - afterall I only put 25,000 miles on it, driving it every day in 3 states of tune over a total of 18 months.

Clearly I'm talking bollocks

 

Easily lose you 2mph on a trap - massive IMHO. I can even feel it but then I'm hyper sensitive to these changes. I could feel 3bhp on a 300hp car - pretty confident of that.

 

I think you are wasting your time on this one .

As you know unsealing the air box cant do anything but murder the cars performance , but peeps get so excited about the noise, they think its faster .

On my bike , we go to great lengths to seal the air intake tubes to prevent any leakage .

I will try it without the lid on one day , maybe we have been missing a trick

 

I don't deny the noise is good - I ran the car like that myself for a bit but ultimately losing some performance bugged me more than the noise excited me.

 

Time to start modifying it.

Could I suggest a change of final drive ratio ........ or a supercharger.

 

How do you go about re-oiling the filter

Also, my brother has a Clio Sport (172) and I've been driving that recently. It feels faster than the S but I put that down to the lower traction. In the S you can floor it in 1st from a standing start without wheelspin, infact its hard to get the wheels to spin on a dry day with warm tyres (wet is no contest ). Whereas the 172 is a beast and will spin in 1st or 2nd if you give it too much right foot at the wrong time. This all adds to the sensation of speed I think.

I have been driving it with the air box lid off, i doubt it makes much difference at speed due to the volume of air entering the engine bay. Difficult for the engine heat to affect it. Though I think your and my idea of "much of a difference" may be quite different

 

I havent read hte replies but its warmer out there, so it will feel slower.

 

IMHO it does - the engine bay is quite tight and with the low bonnet profile there isn't much circulation space. Also remember that there isn't a direct flow or line of air over the area where the filter is.

If you can be bothered search some of my very early posts on this forum and you'll see a number of threads that I started on this issue. I was very dissapointed with the performance of the car when I first got it and also how it faired against supposidly slower cars. It wasn't until I got a standard airbox (with lid on) that I was happy.

I'd be confident this is the issue. You've perceived a loss of performance that has bothered you enough to post about. When I owned your car I experience the exact same thing with anything other than an enclosed airbox and it bothered me enough to post also. Ergo, put the lid back on or accept your car will be slower than standard

By the way it wasn't just me that noticed the difference, two of my car enthusiasts mates could feel the car was much more urgent once I'd binned the I.K and notions of lid-off driving.

Not sure re-oiling. All I know is that K&N's need a clean and oil every now and then (I think you get special filter oil)

 

Thats about as much as I know too

I'll check the throttle cable, hear if the butterfly hits the body when the accelerator is planted on the floor. Check the slack too.

What about an ECU reset, is that somthing you do periodically? What is the procedure for this? Remove fuse to reset then replace. Idle the car for 3 cycles of the fan (On Off On Off On Off). Then you're good to go?