XJR6 Engine ECU Successfully Remapped
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Senior Member
Joined: Jan 2012
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From: UK
Hi Fabian,
There is no need to fit a standalone engine ECU. The probable reason that your engine won't start is that your engine ECU is fitted with engine immobiliser software. This will prevent fuel injection, unless you fit the whole security system. I can provide you with a Jaguar production engine ECU hardware without immobiliser function. This will provide yuo with the same level of driveability as the original XJR6. I have provided many such engine ECUs over the years to other owners installing these engines into other Jaguar and non-Jaguar vehicles. I also reprogramme the ECUs to advance the ignition timing to provide more performance. If you happen to also be performing a auto to manual conversion, then I can also reprogramme the ECU for the change in transmission. Please email me directly (andystodart4@gmail.com).
There is no need to fit a standalone engine ECU. The probable reason that your engine won't start is that your engine ECU is fitted with engine immobiliser software. This will prevent fuel injection, unless you fit the whole security system. I can provide you with a Jaguar production engine ECU hardware without immobiliser function. This will provide yuo with the same level of driveability as the original XJR6. I have provided many such engine ECUs over the years to other owners installing these engines into other Jaguar and non-Jaguar vehicles. I also reprogramme the ECUs to advance the ignition timing to provide more performance. If you happen to also be performing a auto to manual conversion, then I can also reprogramme the ECU for the change in transmission. Please email me directly (andystodart4@gmail.com).
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Senior Member
Joined: Jan 2012
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From: UK
I can increase the engine speed at which the rev limiter takes effect, but not technically remove it. However, as I see you are in the USA, I assume that your X306 is automatic, in which case the transmission will upshift before the speed reach the rev limiter, unless you use the J-gate to hold the gears down. The rev limiter in the manual cars is set to 5,950rpm. If I set the rev limiter any higher, there is a risk of overheating the crankshaft torsional vibration damper. Unless you change the cam timing, the engine won't make any more power, just by increasing the engine speed.
Junior Member
Joined: Jun 2023
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From: brisbane
XJR 6 Ecu remapping
I thought that some of you would be interested to read that I have now succeeded in remapping an XJR6 Engine ECU. I have spent the morning driving my 95MY manual XJR6 fitted with an engine ECU that has revised ignition and fuelling maps that I have created myself.
Last weekend I removed the standard ECU from my car and dismantled it. I removed the two EPROMs (Erasable Programmable Read Only Memory), otherwise known as “chips”, from the sockets that are soldered onto the printed circuit boards. I copied the hexadecimal data from these chips into a PC. I was then able to manipulate this data to advance the ignition timing and reduce the level of fuelling over-enrichment.
I then loaded the revised hexadecimal files into two new chips. These chips were then fitted to an ECU that had previously been fitted to a 3.2L X300. It is this ECU which I now have fitted to my XJR6.
Using this same process, I can, in principle, change any of the data in the ECU. There are over 600 constants and 200 maps in the ECU so the possibilities for making changes are enormous. The key is being able to find where any individual map or constant is located in amongst all the data and knowing by how much to change it. Fortunately, as I was originally responsible for creating much of this data when I worked at Jaguar, I have a big head start compared with anybody else trying to perform this process. I hesitate to refer to what I am doing as “chipping the ECU”, since the companies who “chip” cars rarely have access to the “inside information” that has allowed me to reprogramme these ECUs. Nonetheless, it is a term with which many of you are no doubt familiar.
I normally assess potential improvements in engine performance by measuring in-gear acceleration times. It is important to perform the tests on a level road, with the car at minimum kerb weight, AC off and at a typical ambient temperature in order to make comparisons. I log vehicle speed using software on a laptop PC connected to the car’s diagnostic connector.
From these measurements I have calculated that the in gear acceleration times over the full engine speed range has reduced by 7% compared with original road test of this car. I think this is quite an achievement for a car which is 17years old and has no mechanical modifications that would improve its performance.
I will be developing further changes to maps in the ECU to improve performance and fuel economy in the coming months. If anyone is interested in having their ECU reprogrammed then post your questions here or feel free to contact me directly.
I shall be concentrating my effort on reprogramming ECUs for XJR6 vehicles, as these tend to be driven by owners interested in high performance cars, but it would be possible to apply the same process to the ECUs for naturally aspirated 6 cylinder X300 cars (X304).
I will be continuing to offer my revised crank sensor bracket as an alternative method of providing increased ignition advance for all AJ6 and AJ16 engines.
Last weekend I removed the standard ECU from my car and dismantled it. I removed the two EPROMs (Erasable Programmable Read Only Memory), otherwise known as “chips”, from the sockets that are soldered onto the printed circuit boards. I copied the hexadecimal data from these chips into a PC. I was then able to manipulate this data to advance the ignition timing and reduce the level of fuelling over-enrichment.
I then loaded the revised hexadecimal files into two new chips. These chips were then fitted to an ECU that had previously been fitted to a 3.2L X300. It is this ECU which I now have fitted to my XJR6.
Using this same process, I can, in principle, change any of the data in the ECU. There are over 600 constants and 200 maps in the ECU so the possibilities for making changes are enormous. The key is being able to find where any individual map or constant is located in amongst all the data and knowing by how much to change it. Fortunately, as I was originally responsible for creating much of this data when I worked at Jaguar, I have a big head start compared with anybody else trying to perform this process. I hesitate to refer to what I am doing as “chipping the ECU”, since the companies who “chip” cars rarely have access to the “inside information” that has allowed me to reprogramme these ECUs. Nonetheless, it is a term with which many of you are no doubt familiar.
I normally assess potential improvements in engine performance by measuring in-gear acceleration times. It is important to perform the tests on a level road, with the car at minimum kerb weight, AC off and at a typical ambient temperature in order to make comparisons. I log vehicle speed using software on a laptop PC connected to the car’s diagnostic connector.
From these measurements I have calculated that the in gear acceleration times over the full engine speed range has reduced by 7% compared with original road test of this car. I think this is quite an achievement for a car which is 17years old and has no mechanical modifications that would improve its performance.
I will be developing further changes to maps in the ECU to improve performance and fuel economy in the coming months. If anyone is interested in having their ECU reprogrammed then post your questions here or feel free to contact me directly.
I shall be concentrating my effort on reprogramming ECUs for XJR6 vehicles, as these tend to be driven by owners interested in high performance cars, but it would be possible to apply the same process to the ECUs for naturally aspirated 6 cylinder X300 cars (X304).
I will be continuing to offer my revised crank sensor bracket as an alternative method of providing increased ignition advance for all AJ6 and AJ16 engines.
Regards Vaughn
Veteran Member
Joined: Oct 2021
Posts: 1,387
Likes: 564
From: Sydney
ok so...
i am unsure if you have seen my posts regarding my car running rich and associated issues or not.
but i am thinking that potentially it is the ECU.
as i really dunno otherwise.
wondering if maybe this is something that could help?
also noted that i only run 98 RON fuel here so could maybe tune better for that?
if this is something worth looking at what would be the cost of doing this?
i have a parts car so do have a spare ECU.
i am unsure if you have seen my posts regarding my car running rich and associated issues or not.
but i am thinking that potentially it is the ECU.
as i really dunno otherwise.
wondering if maybe this is something that could help?
also noted that i only run 98 RON fuel here so could maybe tune better for that?
if this is something worth looking at what would be the cost of doing this?
i have a parts car so do have a spare ECU.
Thread Starter
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Senior Member
Joined: Jan 2012
Posts: 838
Likes: 689
From: UK
Hi Carnage,
Yes, I still reprgramme Jaguar AJ16 engine ECUs for owners with specific requirements. Pease contact me directly (andystodart4@gmai.com) for more details. If you just want a bit more performance and fuel economy, I would recommend my revised crank sensor bracket as the most cost effective solution.
Regards,
Andy Stodart
Yes, I still reprgramme Jaguar AJ16 engine ECUs for owners with specific requirements. Pease contact me directly (andystodart4@gmai.com) for more details. If you just want a bit more performance and fuel economy, I would recommend my revised crank sensor bracket as the most cost effective solution.
Regards,
Andy Stodart
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Senior Member
Joined: Jan 2012
Posts: 838
Likes: 689
From: UK
Hi Spud Maat,
I have read some of your posts reagrding rich running. Failure of the ECU itself is very rare. Unfortunately, I don't repair ECUs. I can reprogramme an ECU for you, and add extra ignition advance for running on 98RON fuel, at he same time, but it may well not fix your problem. I assume that as you have tried another ECU, that there were no signs of corrosion on the connectors of the ECU hat you removed. Water ingress into this connector is a know issue on X300. If you have tried running the engine on the spare ECU from your "parts car" and it runs really badly , the other ECU may be "orientated" to have the oxygen sesnor connected the other way around. You could try swtiching (front bank to rear back and vice versa) the oxygen sensor connectors to the harness and see if it run any better.
I have read some of your posts reagrding rich running. Failure of the ECU itself is very rare. Unfortunately, I don't repair ECUs. I can reprogramme an ECU for you, and add extra ignition advance for running on 98RON fuel, at he same time, but it may well not fix your problem. I assume that as you have tried another ECU, that there were no signs of corrosion on the connectors of the ECU hat you removed. Water ingress into this connector is a know issue on X300. If you have tried running the engine on the spare ECU from your "parts car" and it runs really badly , the other ECU may be "orientated" to have the oxygen sesnor connected the other way around. You could try swtiching (front bank to rear back and vice versa) the oxygen sensor connectors to the harness and see if it run any better.
Veteran Member
Joined: Oct 2021
Posts: 1,387
Likes: 564
From: Sydney
Hi Spud Maat,
I have read some of your posts reagrding rich running. Failure of the ECU itself is very rare. Unfortunately, I don't repair ECUs. I can reprogramme an ECU for you, and add extra ignition advance for running on 98RON fuel, at he same time, but it may well not fix your problem. I assume that as you have tried another ECU, that there were no signs of corrosion on the connectors of the ECU hat you removed. Water ingress into this connector is a know issue on X300. If you have tried running the engine on the spare ECU from your "parts car" and it runs really badly , the other ECU may be "orientated" to have the oxygen sesnor connected the other way around. You could try swtiching (front bank to rear back and vice versa) the oxygen sensor connectors to the harness and see if it run any better.
I have read some of your posts reagrding rich running. Failure of the ECU itself is very rare. Unfortunately, I don't repair ECUs. I can reprogramme an ECU for you, and add extra ignition advance for running on 98RON fuel, at he same time, but it may well not fix your problem. I assume that as you have tried another ECU, that there were no signs of corrosion on the connectors of the ECU hat you removed. Water ingress into this connector is a know issue on X300. If you have tried running the engine on the spare ECU from your "parts car" and it runs really badly , the other ECU may be "orientated" to have the oxygen sesnor connected the other way around. You could try swtiching (front bank to rear back and vice versa) the oxygen sensor connectors to the harness and see if it run any better.
would switching the sensors cause any issue or will it just be a matter of either better or worse and switching back will just go back to how it was?
the parts car currently runs like crap, idles real low and blows white smoke so i believe its poor running to be mostly due to maybe busted valve seals.
will certainly give switching the 02 sensors a go.
on the weekend i may even try switching the ECUs back and seeing what data that shows.
Last edited by Spud Maat; Oct 8, 2024 at 02:11 AM.
Senior Member
Joined: May 2015
Posts: 599
Likes: 91
From: Canada
i had that thought regarding the 02 sensors and i visually checked the wiring and the 02 sensors on each car appear to be connected to the same plugs.
would switching the sensors cause any issue or will it just be a matter of either better or worse and switching back will just go back to how it was?
the parts car currently runs like crap, idles real low and blows white smoke so i believe its poor running to be mostly due to maybe busted valve seals.
will certainly give switching the 02 sensors a go.
on the weekend i may even try switching the ECUs back and seeing what data that shows.
would switching the sensors cause any issue or will it just be a matter of either better or worse and switching back will just go back to how it was?
the parts car currently runs like crap, idles real low and blows white smoke so i believe its poor running to be mostly due to maybe busted valve seals.
will certainly give switching the 02 sensors a go.
on the weekend i may even try switching the ECUs back and seeing what data that shows.
Veteran Member
Joined: Oct 2021
Posts: 1,387
Likes: 564
From: Sydney
lucky for me its the parts car...
was hoping it had a great engine, seems like the guy loaded it up with stop smoke before i got it. lol.
saw no evidence of smoke on the 1000km trip home with it.....
my original ECU was LNA1410GF/301 (2/95)
the one i putr in is LNA1410WB/301 (8/95)
can't see anything bout what the GF and WB differences is.
Last edited by Spud Maat; Oct 8, 2024 at 04:04 AM.
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