In anticipation of perhaps changing out the stock air filter and intake pipe on my XKR, I was doing some investigation of the stock unit. The first question is how to remove the existing intake box. I was playing around yesterday and got to a point where I was stumped. I removed the large tube (from the intake box to the throttle body), removed the clips that hold the top of the intake box to the bottom so that I could remove the filter, and then removed the retaining nut that holds the base of the box to the wheel well (the nut that screws onto a stud at the outboard side of the box). At that point, when pulling up on the base of the box there was still resistance and I did not want to force. Part of the resistance is from the intake horn that goes from the box into the wheel well. This is supposed to be removable from the base of the box but I could not figure out how. The other resistance was from the base of the box at the bottom and towards the front of the car. By feeling around it feels like there might be some stud at the base of the box that fits into a metal bracket. Does this just press fit into the bracket?

Now the technical question. Assuming that I can eventually remove the box, the XKR intake has an actuator that opens another port on the box when needed for more air. I assume that defeating this and keeping the secondary intake always open would end up triggering a trouble code or 'check engine light'? But what happens if I replace the intake with an aftermarket one? If I disconnect the secondary intake actuator electrical connection to remove the stock box then I assume that will also trigger a trouble code. Or do the aftermarket intakes somehow retain the secondary actuator connection?

Thanks in advance for any experts out there with the answers.

Doug

 

Before changing you intake, perform a quick test.. go into your engine and either detach or prop open the secondary air flap and go out for a drive.. jam the gas pedal into the carpet and watch what happens... you will immediately notice that your car has no torque.. Our engines are very picky about how much air they want to run hard and I dont think there is an intake available currently that will give you gains throughout the RPM range.. you will either end up with more high end HP and no TQ or more low end TQ and your engine will starve in high rpm's.. good luck with the intake and let us know if you experiment, but I'm working on a new setup with a custom upper tube and a larger diameter ram air tube that will retain the stock air box and will still receive cold air through the grill and use the secondary flap, but its definitely not easy.. Don't let me deter you from experimenting though, the more people we have working on this, the better the chances are for success......

 

I would just drop a K&N filter in the factory box. These cars are so sensitive. My XJ8 would not run properly with a cold air intake.

 

ive put several on without issue, but you need to clear out long term fueling corrections in the ecu by doing a hard reset. to do remove the negative terminal from the battery and touch to the still connect postive terminal, if it wont reach use the wrench you just loosen the cable with as an extension. Hold for 10-15 sec, this discharges all capacitors on the car by giving them a path to ground. also usefull if you dont want to wait 45 minutes to remove air bags.

 

I do recall that doing things like removing catalytic converters or adding headers often results in loss of low end torque but increase in horsepower so I guess the same would apply for an intake that is too nonrestrictive. Still I would like to know what I am missing in being able to remove the box. How does the air horn disconnect from the box and what is holding the box at the bottom/front.

BRUTAL Are you sure it is safe to touch the negative cable to the still connected positive terminal? I thought that you could clear codes by just disconnecting the battery for 15 minutes or so. I also thought that the computer will relearn on its own after driving about 50 miles.

Doug

 

That reset is good to correct a lot of problems. Just remember that you will have to reset any memory functions. Touching the negative cable(After disconnecting it) to thepositive cable is safe and will clear all memory. I usually disconnect it for about 15 minutes and then touch it to the positive cable. This allows the capacitors to drain slowly, but clears all if any energy is left. I think it is just less stress on the systems. Just my PO. These cars are wonderful cars and are Grand Tourers, not gut wrenching sports cars. Doug, your XKR has plenty of power for its use. If you really wanted a speedster, you should have bought a Viper or some such similar car. Just enjoy the beautiful car as it is. It is a gorgeous car!!

 

I guess it is just a habit I carried over from my long ago muscle car days (1970 Plymouth Roadrunner) as well as my more recent muscle car days (Vette). There was always some tinkering or bolt-on you could do to (hopefully) tweak out a bit more oomph. Less restrictive air intake seemed like one of those easy-to-do tweaks with little risk and I still get a bit of a kick from fumbling under the hood. However, for now I will probably leave well enough alone.

Doug

 

Did you read whiteSTRs posts just recently where he was messing with his intake and now he has horrible knocking and worry? Just saying...

Live in comfort that you hold about 100 more horses than us normal xk8 owners, which is nothing to spit at.

 

As a matter of fact I did read the whiteSTR post and it made me feel horrible for the guy. I suppose it could just be a cruel coincidence but it almost seems like he sucked something into the intake.

It reminds me a something I did in my much stupider days when I was tinkering with a carburetor setting on my 1970 Roadrunner. I was using a drill bit to measure some setting (engine not running) and of course I dropped the bit. I saw it lying inside the intake manifold but I did not have anything long enough to grab it. I needed one of those magnetic probes and it looked to me like the drill bit was not going to go anywhere so I decided to drive to the hardware store to get a probe. After a couple of blocks I heard a terrible rattling and I stopped the engine. Of course the bit worked its way down the intake and to the valve and got shattered into pieces, some of which damaged at least one piston.

Whenever I recall this incident (seems like just yesterday) it always amazes me how dumb I was.

Doug

 

Haha are you guys talking about me? I feel like such a hypocrite lol right after I told seismec guy to leave his intake alone I went outside and started messing with mine.. I left my filter in the airbox so I'm very certain I did not suck anything into the throttle body, intake, or heads.. but I think I may have leaned the car out enough to detonate and cracked a piston (which I did not think you could do on these cars) either that or my supercharger was on its last leg and I recently installed a new blower belt, new tensioner, plugs, and an x-pipe.. which may have been "the straw that broke the camels back" as they say.. Anyways from what I can tell from listening to it the rotors are hitting the top of the case which is common in lightnings.. I'll know tomorrow morning so I guess theres no sense in worrying about it till then.

 

whiteSTR: I forgot it was you who offered some advice to me on the intake. This reminds me of the thread I started about the convertible top hydraulic leak where someone pointed out that just talking about these problems seems to make them happen to others

By the way, you used the term 'lightnings' in a few posts. What is that?

Doug

 

Super charged F150

 

'Lightening' = Ford supercharged truck.

These cars are like sewing machines. Everything has to work in exact order. Mess with one thing and it puts everything out of whack! If you have to play under the hood, play with a damp rag and keep it clean.[sm=goodidea.gif]

 

I may be wrong but I think you are telling me not to screw with the car. Just guessing[X(]

 

I can't comment on you screwing your car Seismic. But I can ask a question...

You know how when you buy a cheap old car, likea Vauxhall Vectra 2.5V6, it sounds meaty, sounds nice. Purrs at the lights and roars off when you want to go beat the guy next to you off at the lights.... Well. These Jags are so refined and sweet that even when you drive real fast, you still can't hear the thing!! I bought a V8, I want to hear a V8!!! Is there anything you can do, (like drill large holes in the air intake!!) to make it sound really nice? I don't want to spend a grand on a new exhaust either...!

 

oh comeon guys lets not be pansies, there are always improvemnts to be made from factory as long as you dont fall for tornados, throttle body spacers, and magnets for air and fuel, (I know I missed a few) get this http://www.gtechpro.com/ $200
to baseline your car, for around town torque improvements nothing beats 60' times and 0-60mph times, then qtr milefor overall prformance.
next try some tried and true mods, drop in air filter, cold air intakes, opening the secondary air inlet, exhaust, bigger crank pulley for sc cars etc.....
Then be one of the people here that instead of theorising results you test them, and seismic, since youre and engineer this should be right up your alley.....Just being Brutally honest here, dont fear the unknown, or the man, embrace it, learnit, love it.....theres nothing better than really learning your car and making it yours with well executed mods......

 

It really was the tinkering itself that brought a measure of enjoyment and accomplishment rather than the (perceived) improvements. The thing about the Corvettes (especially the vintage I have) is that they are pretty responsive to small $ improvements such as higher ratio rocker arms, cams, headers, and other bolt-on type of work. For under $1,000 you can easily get 25 to 50 more horsepower at the rear wheels with those cars.

One of the common complaints was the wimpy exhaust sound (also goes for other cars as well) hence there was always a ready market for aftermarket cat-back systems. In my opinion, these are the worst bang-for-the-buck as they typically only pick up maybe 10 to 12 more horsepower at the expense of noise and resonance in the cabin (expense for these systems was also quite high, especially the ones for the Jaguars).

The sewing machine analogy is a good one for modern cars where everything is micromonitored by the computer. Making a change in one area can result in poorer performance as the computer tries to compensate. I guess with current generation cars you really need to get into the computer to coordinate any mechanical changes with new fuel curves, etc.

Doug

 

This is very true, new cars come very de-tuned from the factory.. some of the biggest power to free up comes from retuning the computer.. changing shift points, shift pressure, removing the top speed limiter, timing, and changing air/fuel ratios.. Although I love my Jag I think Im done trying to make it faster.. I'm actually getting a trailblazer SS and buying: superchips, a cam, heads, and a new 3800 converter and I should be in the low 12s.. Our cars are great grand touring cars, but they are definitely not supercars, nor built to be beat on or drag raced.. Chevys can take a beating better than our cars can and when you break your Jag parts aren't cheap.. I did exhaust on my Jag and I will soon be getting it chipped, and thats as far as Im going with this car. Jags dont like being abused as I have learned and although they are great cars, I need something tougher..

 

Pretty much! If you have any kind of warranty, leave well enough alone. After all warranty is gone, then you can play all you want. Just remember that parts for these cars are very expensive. If you want one to play with, go get an older one that won't make you upset if it blows up!!