OK, got the Jaguar (factory stock) XKR-S ECU file uploaded to the 2011 XF 5.0 Supercharged via Jaguar's factory SDD laptop on Sunday. The car has zero modifications other than this software swap. After a long drive back from LA to the SF Bay Area (about 800 miles of driving after the flash) I can report the following:-

• It takes about 100~200 miles before all the following are realized.
• For the first 5~20 miles you may not feel a big difference.
• The popping and overrun backfiring you find on the 5.0 S/C is gone. Now no matter how I blip the throttle and let go in Park or Neutral it'll no longer backfire and pop. I'll let you decide if that's a good thing... some people like the rawness of the popping and crackling.
• The car is notably stronger when you prod the throttle and the engine downshifts to 3000 or 4000 rpm from a cruising rpm of 2100 or so.
• At full throttle running to the red line there is more pull all the way to 6800 rpm although more so at 5000~6000 than at the very end of the rev range.
• There are no drivability issues, no check engine, no codes.
• Tranny holds and does not slip at full throttle (at least not yet and I hope it stays that way).
• The car is actually softer and throttle tip in less aggressive at idle to 2000 rpm or thereabouts, but the car is a little smoother actually.
• The engine feels slightly less linear... where the 470hp (factory stock) program for the XF 5.0 S/C is generally linear and electric motor like from 2800~ about 6000 rpm. The (factory stock) XKR-S program causes the engine to feel notably stronger at 4000~5000 and while gains are less pronounced at 3000 or near the redline.

 

How did they install that file as they are vin specific to the car? Did they use SDD or Legacy? I am very curious as how this is done. Please let us know. Why does it take so long to adapt? We tune Jaguars on a dyno & see the changes immediately?

 

Files are not VIN specific. They are however vehicle type specific. You RENAME the XKR-S file so it has the same file name as the XF Supercharged file. Of all the modules, only the ECU module in the directory is replaced. All the files are already on the factory diagostic laptop. SDD was used.

I am pretty sure there is a difference immediately upon flashing, but it is way more pronounce after a couple of days of driving. This may have something to do with the fact that flashing also means that you wiped all the adaptions previously present. If you simply reflashed the stock XF S/C file with the stock file XF S/C, you'll notice that the car will be a little weak and soft for a while anyway. BTW, a side effect seems to be that the Trip A/B/Auto Info -- MPG, miles driven, range, etc. -- got wiped too when a flash is done.

As far as the rest... well... this isn't exactly "authorized" so I won't say who did it or where.

Don't have time to do a dyno pull yet... maybe in a week or two after I retire a a few back to back business trips and a **** load of work in between.

 

Looking forward to seeing your dyno chart and how much hp and torque you gained from the stock S/C tune. I am also curious what the curve and AFR look like from Jaguar, as opposed to my custom tune.

 

At higher rpms it'll peg rich

 

That's what my stock XFR AFR did but want to see if the XKR-S does it as well. Also wondering how the hp and torque are distributed after the driving impressions of the OP.

 

80hp gain and a car that is now less responsive, with quieter exhaust and no more flat power output.

Sounds like somebody de-tuned the car instead.

 

I was also curious as to why the car would be quieter? I don't know much about the re-tune thing other then what it felt like on past own cars but it seems to me that it should sound more aggressive. I really would like to see what the number say?

 

I can confirm that my XF SC crackles, farts and gurgles when I lift off from the accelerator and I cannot get one pop out of my XKR-S, not lifting off nor downshifting. Seems to me the XF SC runs way richer causing the over run. The XF has two resonators and the XKR-S is straight and an x pipe and has no pops.

 

I've modified my exhaust to mimic the XFR-S (both resonators removed, x-pipe installed and valve delete performed) and I have no popping at all on decel. Spoke to my tuner about that today and a properly tuned engine shouldn't have much of that if any. He said some M5 owners asked if they could add that sound to their tune and they said no, a properly tuned engine shouldn't do that.

 

Well, the XF S/C with XKR-S software alone has zero farts and crackles. It used to do it 80% of the time I blip the engine hard in Neutral or Park. Now, I can't get it to do it even once and I have tried at least 50 times.

Such popping and farting antics come from one of two things (or both). The mixture is too rich. Or, the ECU is slow to react to a suddenly closing throttle or supercharger bypass valve. The latter stems from the fact that when you suddenly lift The throttle plate closes and the supercharger bypass valve opens to vent the plenum pressure. So the is almost immediately less air going into the cylinders. However, it may take the airflow meter a split second to register reduce airflow. If you simply based the fuel metering on the real time airflow meter reading you'll be very rich for a split second. When that fuel loaded exhaust reach open air it suddenly find oxygen to burn, detonate or conflagrate... hence the popping sounds. So, sometimes it is necessary for the programming to override air meter readings and forcibly prescribe a reduced injector pulse when a sudden throttle closure is detected.

Whatever the XKR-S program is doing -- either running leaner overall or doing the aforementioned -- it is not popping. I also notice that the tip in and let off is less aggressive off idle. Maybe that is another reason why -- it simply doesn't allow the throttle to close as fast!

As far as the previous poster's comment that this amounts to a "detune", well... the maximum power and torque output definitely felt higher. Less darty throttle response may or may not be less desirable, but it has very little to do with output. When puttering around the parking lot the XKR-S program definitely feels (and sounds) smoother, more refined and more restrained. Maybe they intended the XKR-S to be less raucous? Whatever it is this is the behavior of the tune and this is not a sticking point for me.

 

I am very confident that my SC with stock tune runs rich. When I let it coast in gear and just lightly touch the gas pedal I can make it pop almost indefinitely. The exhaust tips on my SC are always dirty. The exhaust tips on my XKR-S are still shiny.

 

Well... most factory calibrations bias towards rich mixtures -- not just Jaguar, almost manufacturer's tune for just about every car.

One part of gasoline requires 15 parts of air (by mass) to fully burn. This generally produce the lowest hydrocarbon (unburnt fuel) emissions. This however is generally not ideal ratio for maximizing output it turns out that -- depending on the engine -- the optimal ratio for power production is between 12.8 to 13.5:1. This is because mixing of fuel and air in the cylinders when the spark fires is never perfect (truly homogeneous). It is hence best to run slightly rich of stoichiometric to ensure that all the air is actually used. Using all the air is more important that using all the fuel because it takes a lot of effort to bring the air into the cylinders -- you have to suck it in (or stuff it in in S/C or turbo engines) through valves, throttles, passages, etc. all of which induce pumping effort and losses. Generally speaking the better designed the combustion chamber, induction system and airflow dynamics, the "leaner" the ideal mixture is.

Now, when you go leaner than "ideal" the engine runs hotter. Hydrocarbon emissions fall, oxides of nitrogen emissions increase and you are more likely to knock and ping. You actually don't lose much, if any, power going slightly leaner than optimal. This is because while slightly less than 100% of the air is used in combustion, the increase in combustion temperature compensates and create similar pressures which is what drives those pistons. Fuel economy actually improves. A lot of people can't grasp a simple fact, but it's true... combustion in an oxygen rich environment produces a hotter flame -- taken to the extreme is a blow torch!

If you go richer than "ideal" the engine runs cooler. Although all the air is generally used, reduction in combustion temperatures actually reduces the working pressure in the cylinder and you lose power. Hydrocarbon emissions increase because there is now more unburnt fuel in the exhaust which shows up as sooty stuff around the exhaust tips amongst other symptoms.

So... back to the best fuel ratio for your engine. Generally speaking you'll find that at around 13.2~13.5:1 in modern 4-valve engines with ideal valve angles and a central spark, probably closer to the leaner side on direct injected examples like the 5.0 AJ133. Going richer you lose power, increase fuel consumption & increase hydrocarbon emissions. Going slightly leaner you generally make about the same power as optimal, reduce fuel consumption & increase NOx emissions. Going really lean you lose power, reduce fuel consumption, increase NOx emissions and... ooops... run into detonation or pre-ignition.

So, why do manufacturers generally go richer than optimal instead of optimal? It is not because they haven't tested enough to find the optimal ratio or they don't know that optimal is optimal! Manufacturers spend thousands of hours on the engine stand and tens of thousands of miles on test circuits validating their tunes. No tuner does that. The amount of engineering and expertise manufacture bring to bear in a year greatly exceed all the resources any tuner can spend in ten years. They do it intentionally! They do it because environmental factors and fuel quality is not assured. And these can tilt the actual optimal ratio slightly. And, they don't want to EVER, EVER, be in the leaner than optimal column. Why? To start with, if mpg is 1 mpg worse it's a number on the window sticker and it may affect their CAFE rating slightly. If the engine runs lean, NOx goes through the roof and they fail emissions. You can sell a car with slightly worse mileage. You cannot sell one which fails emissions during regulatory certification. If they run into a situation where a good number of cars are failing emissions later in their service life that's a bank busting recall! Also, running leaner than normal with bad gas or low octane gas can lead to pinging, knocking and engine damage. Bad for reputations and bad for the bottom line from warranty costs. Generally speaking they go about 1/2 to 1 point richer than they know is ideal. Mercedes for instance is famous for running almost 1 point richer.

So... what should you do? Well, most people here are not going to write their own fuel maps. Instead they rely on tuners or swapping to other factory ECU programs. Generally, I like it as lean as it'll pass SMOG and is safe with Regular 87 (some power loss it OK, pinging is not). I am sometimes concerned by how much some tuners push it to the lean side. I like it at about 13.2~13.5. I don't want it at 14:1. Power will be about the same, mileage will be about 0.3~0.5 mpg worse than the leanest tune that makes maximum power, but I don't want to risk emissions and pinging. I ALWAYS try a tank of 87 octane with a tune. I don't want to see any fault codes, CEL, noticeable pining or anything like that. If can run soft or run weak, that's OK. But I generally demand that the tune pass the 87 octane test!

I am 1/2 tank into the 87 octane fill up with the XKR-S program. So far no deal breaking problems. Intitially, there was some hesitation when going full throttle, but that has gone away and now it's just softer and less punchy on the downshift. So far so good.

 

Could you please guide me on where
To find information on which filename is for which ECU?im trying to find the 5.0 n/a ecu file in the sdd flash folder, not sure what is what.

Thanks.