Will after sending my ECU off for a reflash I haven't driven the car very much as I've been rather busy. Everything ran great when i got the ECU back but after about 200 miles all of a sudden it felt slow(in relative terms) again. So to make sure I wasnt crazy I take it to the track yesterday hook up my OBDII data recorder and guess what 12.5@118MPH and back to stock 9psi of boost.

So now this has happened twice so I'm wondering if a certain batch of ECUs are programmed to reflash themselves or place stock parameters back if they see numbers that are off during a self diagnosis maybe performed every few hundred miles. I don't know I'm baffled as I've never seen this happen but have heard about it on other cars.

Any ideas out there from guys that have deep ECU knowledge, as this issue is getting quite frustrating.

 

Sounds most frustrating. I've been wondering about that which is why been waiting for you to go back to the track for an other test.

I don't have an answer. The only thing I can add that Jaguars WILL auto flash under some circumstances. When I had my '05XK, the adaptive cruise did not work so, I looked for a fault code. There was none but, I still pushed the reset button. It ended up erasing the ECU and the car immediately went into limp mode.

I figured that I had to hire a tow truck to the dealer.... but, to my surprise as I came back to my car an hour later it was in the process of automatically refleshing the ECU. When it was done the car run fine but, the flash was an old, outdated version that I had to have the dealer update.

So, it my be exactly as you suggest. When the car senses a non-spec firmware, it may revert to a backup firmware. Bummer but, I am sure the aftermarket should be able to get around it.

 

I will be most interested in seeing how you resolve this as after the body mods get done to my newly acquired XKR, I had planned on having the tune done. Keep us posted as you get more information.
Thanks

 

Its getting to be quite frustrating to say the least, I'm waiting on jerry to get back to me and will keep you guys updated as to what may be happening.

I also spoke with Hershel form RSC yesterday and his tuner will be in Miami in the next few weeks and he mentioned an issue with the '13 Jaguar and LRs that would not hold a tune(before I brought it up) and that there is a separate area of the ECU that also needs to be flashed.

I work in IT infrastructure and understand Intel based products like the back of my hand but I have no idea how factory ECUs are designed. Although it would be very easy to have a ROM with base tune and programmatically check certain checksums in the operating program. If they are wrong then they can be overwritten with what is stored in the ROM. That makes sense but again I have no idea how the code in the ECUs is written other than it being low level Assembly language, in which I am definitely not an expert.

I just want a tune to stay around for more then 200 miles LOL

 

I believe it isn't written in Assembler and that there isn't enough space for 2 lots of firmware so I am very doubtful that it can do such a restore. It's my understanding that the code runs from ROM not RAM. See if your tuner has evidence.

 

It has to run from ROM but you can always have a backup and thats what I was told by another tuner. I'm not sure I don't have firm data as to how they are designed. I was told by a tuner they were in assembler. Thats all I know for sure. gonna call Jerry now and see what he has to say.

 

The suspense is killing me and new I need to know if mine will have the same issue as I was hoping to go down there soon to get it done.

 

They were ASM back in the old days.

 

Is this an issue specific to the newer XKR's? Mine is the 2006 onwards 4.2 XKR. I have had the pulley mod done and is consistently running a higher boost. I checked it on a dyno and at that time I had travelled over 200miles, all good.
I am yet to get the ecu tune done but now worried that I will get the same issues you are experiencing. For me the ecu tune is so that I can get the max out of the pulley mod. Not worried if I don't get it done for a while. I am over the moon with it as is.
Maybe might leave it?

 

Not always.

Sometimes a ROM gets copied to NVRAM, but if the NVRAM gets cleared it reverts to ROM.

That's how upgrades get done. NVRAM is preferred to ROM because memory access is faster. It is also where adaptations are stored.

And it could not be a ROM that was reprogrammed because that is impossible. An EEPROM maybe.

On the types of chips used for the ECU, the bootloader comes up first. That is where the security checks are done including integrity of the bootloader. If that is not defeated, then there are no guarantees as to keeping any modifications. The bootloader is heavily protected.

 

It's (electrically eraseable) flash memory but still tends to get called ROM by some.

I don't think there's anything like enough RAM and it's mostly (or all) volatile.

Really if a tune is suspected gone then time to ask the tuner.

 

Still have not heard anything I have to hit a track day this afternoon but will get the car dynoed again this weekend.

Plums - what you just said is what another tuner told me and he said its an issue hes see on some '13 jags and LRs.

 

Holy crap. I can't believe you're going through this again after having the dealer over write your tune. I've been waiting to see what your track times were before getting my car done. I think I'll leave my car stock. I was so stoked on getting the tune done before, but because of the quality issues mentioned here, warranty and the fact that I like to trade cars every 5-8K miles I'm shying away from a tune for now. Have you been in contact with other forum members who have been satisfied with their tune to see if their tune reverted back to stock? This is a very interesting finding which I hope you get resolved quickly. I'm sure many members appreciate your findings.

 

Well Matt in Houston hasn't reported a reversion on his XKR-S, correct?

I don't have dyno plots to prove it, but I would bet good money that my 2010 has not reverted....

 

Would be interesting to find out by a dyno or track test run. Maybe it IS only with 2013 models?

 

I was at Homestead all day and I was around 10-15 mph under where I was at the end of the straight coming out of NASCAR 3. I was just shifting to fifth before braking for a left and caught myself braking super early the first few laps. My telemetry says a top speed of 142 and I usually see 150ish.

I was also running Identical times 1/8s on Wednesday at ~8.2@ ~92MPH

I'm going to have the car dynoed within the next week and see

BTW: Albert heres a shot of the PSS tires after the second session. Tire temps were 177 outside 178 inside and 180 outside

 

Looks like the car likes the present cambers. I suspect those readings are Outside, Middle, Inside. Close enough to be even temps.

From the picture, nice texture on the tire. Seem to be picking up gravel as you drive off track, indicating to me that the compound gets really soft when it is hot. Just like racing slicks.

 

When this is happening is it putting your 155mph speed limiter back on too?

 

I'm super impressed with the PSS tires I'm pushing them really hard on the track and as you can see they get super soft. That right front was also getting hammered in the banking, I was pulling 1.2G at around 115 MPH through turn 3 and 4. They pick up a lot of rubber as well so when you are leaving the track they feel out of balance until they shed the rubber. The fact that they are not even half worn after monthly track days and 4k miles of driving is pretty impressive.

The guy set up by suspension and alignment was in the garage next to me and said the tires looked perfect. The tire temps across the back are pretty even as well and with the banking the -2.0 in the right rear was an advantage.

 

I have not been able to get to 155, trust me I tried LOL. The best I could pull was a 142 before turn 1 into the road course.