Gidday guys, Just posting in the hope someone has some experience in chip tuning a base 4.2 N/A XK and can comment. At the moment I'm finding my XK a bit sluggish in the mid range and really have to use the kick down to get it moving.

A local performance shop has told me they can increase the car's performance with a dyna tune with about 30 more hp. Their cost is $1100 and they have been in business 30 years. My concerns are will having this done cause any negative effect on the car's reliability and are their claims honest.

In hindsight I should have gone with the 5 litre motor but trying to do the best with what I've got.

Any advice or comments would be very much appreciated!

 

Best 1/4 to date 13.72 @101.5mph
Dare I say it but that's faster than the xf 5.0 and just as quick as the xk 5l

Mods include X pipe mid pipe, old jaguar tune (Cambo) he's on the forums, free flowing cats

Since then I've added a larger throttle body 81mm and 3.58 diff gears .

Unfortunately with the new gearing I definitely now need a quaife LSD to get the most out of it.

 

I was considering a XK and upgrading the zaust to an XKR's quads with new diffuser and a chip tune.

In the end went for an XKR instead

Not a flame suit moment just the truth

 

The xkr is always going to be superior

Larger brakes, stiffer suspension and obviously faster

 

Thanks for the reply Steve. That's all a bit advanced for me but you surely know your stuff!

 

Before you go chasing power with an engine tune, make sure that the car is really in tip-top mechanical shape first.

As the miles creep up, the cats tend to choke, which robs power.

And to really get the most out of an engine tune, you need to improve or restore the efficiency of the engine breathing, air in and exhaust out.

Steve's XK with our custom x-piped exhaust & high-flow cats for example, the exhaust is about as efficient as it can be.

There's not a lot that can be done with the intake, but at the very least ensure that the MAF is clean, and the air filter is a good one, not dirty, etc...

And the usual things like good sparkplugs, clean throttle body, it's not running hot, and so on.

Then think about an engine tune.

We don't have any contacts near Hamilton or Auckland who could flash a tune, there is a forum member in Christchurch who could possibly help, or perhaps in Nelson, but no-one I know on the North Island.

 

it sounds like an underlying issue as Cambo is trying to point out .
the terms sluggish and XK8 don't really go together .
there is an easy laser temp gun technique to check cat converter efficiency . with vids on you tube to follow .
also check your fuel trims , fuel pressure and MAF sensors for accuracy via obd2.


i would send my laptop and VCM to Aukland , if you want to try the correspondence route for a tune .
or diagnosis .
if that would help let me know .

 

Thank you very much for that! I guess the problem I've got is the car seemed grunty at first but having got used to the power feel I'd like to get it a bit more responsive mid range where I either have to drop down a couple of gears or use the kickdown to get it going.

 

Your correct I noticed this as well there is a huge hole down low in torque meaning you've really got to keep the revs nice and high to get it up and going

After the tune and mods it's literally day and night there is plenty of torque now down low in the rev range

 

Oh I'm glad I'm not the only one finding this a problem. Steve, do you think just having the dyno tune will make a difference? I've only had the car a short time and not ready(flush enough) to do the mods you have had done on your car.

 

That will be me. More than happy to coordinate something if you are ever down this way.

 

Brian id simply get a local exhaust shop to add a X pipe to your mid pipe not a hard job at all , tune with our guys on the forum and off you go it's literally day and night with the performance increase

Was Just thinking even easier would be for them to simply retain your rear muffler and add a h pipe just like the quicksilver mid pipe .

 

Thank you so much for taking the time to help me. II will get the muffler shop here in Hamilton to see what they can do. Thanks again!

 

These are the exhausts I get made for us here in Sydney;



It's what's on Steve's XK, my XKR, and a couple of other XKR's in Sydney and Melbourne.

I've got one here from the last batch, but shipping it to NZ would be ~$325 Aussie, and it's $1000 for the pipe, then you have to fit it, it all adds up...

When I first looked at having these made a local well-reputable shop quoted $2k (fitted) to make one by welding individual mandrel bends and tube together.

The guys who make these ones for me use a CNC mandrel bender which brings the cost down considerably.