If you own a Jaguar XJ220 or the rarer XJR-15, you’re probably not short on money or real estate. You may, however, be finding it hard to lay your hands on a diagnostic tool that is compatible with the ancient Zytek ECU. Thankfully, [Tom Radom], is working to change that.
As the owner of XJ220 chassis #50, [Tom] was unlucky enough to see the dreaded check engine light come on last year. He was lucky enough to get his hands on an SPD-1039 interface, built to talk to the Zytek ECU that runs the car. However, he was painfully aware that these devices are now incredibly rare and hard to come by, even given the tiny limited market of owners of 1990s Jaguar supercars. Thus, he set about building a replacement.
An initial effort to open up and reverse engineer the Zytek interface failed, mostly because it had been potted rather successfully in silicone. Thus, [Tom] took a new tack. He hooked up a logic analyser between the interface and the car, recording the traffic between the two. This captured data allowed [Tom] to recreate the interface using a FT232RNL bridge to chat to the Zytek engine control unit. There was no attempt to rebuild the software—the original DOS-based diagnostic still runs perfectly fine in an emulator. It was just the hardware interface from a serial port to the car that needed to be recreated.
[Tom] has been building the modules and supplying them to owners of XJ220, XJ220S, and XJR-15 models at no charge. He believes simply having a viable diagnostic tool available will increase the value of these classic cars by more than the costs he incurred to develop the interface. Interested parties can submit their details via webform on Port220.com.
For a modern vehicle, the ECU is everything. Without it, the car doesn’t run. That’s why we’ve seen some heroic fixes to rescue cars and get them back on the road. If you’re doing your own wizardry to talk to cars of the past, don’t hesitate to notify the tipsline.
I’m very interested into the generic 8 channels logic analyzer’s breakout board the author is using. I wonder if someone out there designed such PCB because the company selling those only sell it in a pricey kit (including expensive shipping from Australia) : https://lonelybinary.com/products/logic-analyzer-kit-8-channel-24mhz-usb
that’s a turn around, we are normally paying the expensive shipping from everywhere else in the world..
Why do you want that one in particular given all the cheap logic analyzer’s on alixpress?
The breakout board with easy to hookup aligator clip is something I never saw elsewhere and it’s a great idea. What’s even more surprising is that the board seems simple (for people who know how to design boards at least, not for mortal like me) so I though clones where available.
Calling $95 for a $10 piece is a little bit bold…
Aliex has some boards with male pin leads, Adding some prototype board, female header and croco clips should not be that problem and seem more flexible to me.
Yeah bodging stuff is possible. I’m looking at a more polished/solid option though.
Given how far ECU’s have come I’d be tempted to just ditch the old Zytek and fit a modern aftermarket one… but then maybe originality matters a little more in this world.
But if you put in a modern ECU, you’d have to put up with the extra power and efficiency that comes with modern engine management and custom tunes.
These are incredibly rare vintage supercars – they made less than 300 and they sell for half a million pounds nowadays. Swapping in a Haltech or something would tank the value and it’s not like there’s off the shelf tunes for something like this. With a lot of work you might see performance/efficiency improvements… but if that’s the goal it would probably make more sense to just buy a different car in the first place!
Yes. To people who have too much money, a vintage collector car that starts every time at the first turn of the key, and doesn’t leave you stranded on the side of the road waiting for the flatbed, and doesn’t spend 3/4 of its life gathering dust in a corner of some obscure specialist garage somewhere, would be a significant loss of value and desirability. They are all about authenticity and are willing to pay for that, in more than just money.
No one wants a rare supercar that ‘just works’. That would be stupid. The whole point of owning these things is the part where you get together with your rich buddies who also own rare expensive collectors cars that also don’t work, and whine and complain and get sympathy from the others who are all going through the same troubles.
if done right why it affect the value? you make the replacement ECU plug in to the existing harness, nothing is changed you can plug in the original any time. If you can find a broken one you can even put it in the same box
If you take your car to a vintage car judging competition, there are experts who will subtract points for you not using the original design of screws to hold the trim on. They’ll deduct points for spotwelds in the wrong place if you’ve repaired a rusted rocker panel with a replacement original factory part. People who want to be competitive in concours car shows will pay for originality and cars like these are what go to those shows, and if you’re rocking a whole replacement ECU your car will work great but won’t be even slightly competitive, which will reduce the value because a lot of the people who’d pay $400k for one of these won’t look at your specific one.
so put the original in when you want to show off and put the new in when you actually want to use it for what it is made for. So put whole news engine in so that don’t have risk the engine with the matching numbers
Eh, make an adapter harness so there’s no permanent changes – plug in the good ECU when you want to drive it, plug the old one back in if you want to sell it.
Lots of folks race classics using replica parts and keep the originals safe at home.
Upon re-reading the article, what he has done is to recreate the diagnostic hardware, not the ECU. And he’s making them available to other owners, which is the real point (albeit a very limited market — probably don’t need to invest in tooling)
Were the ECU to fail, he’d have no option but to put in a modern one, or design a replacement for the original one with a new processor. Either way, the choice is between having a supercar hangar queen or being able to drive it again. Now is the time to dump the code in the factory ECU, though.
Or fix it.
Or buy a better car. I collect vintage stuff too but my fav. car is a Tarpan Honker.
It’s not a “hangar queen” though but a real car to do real offroad. It was previously used by the police. I’ve fitted it with axles from Patrol, Toyota gearbox and reductor, diesel engine from Mercedes “Duck” and reinforced the frame with steel in places where it often cracks. Trust me it will drive through terrain that would make army with their fancy Ford Rangers pull up and reverse in fear. There’s literally zero electronics and repair parts are cheap. Overall it’s a good car. The biggest problem is cab because it has poor steel and rusts in some places.
the schematic on that site is not only drawn upside down, it is also complete nonsense
Yes very strange. TX is tied directly to Vcc?
and afaict the interface needed is just a 5V uart with both RX and TX inverted, which the ft232rnl can do without any external parts
RXD too…
With TXD and VCC being pins 2 and 20 I thought it might just be a tiny mishap in the “shipped” schematic but both TXD(2) and RXD(3) are tied to USB_5V (but NOT to VCC(20) actually).
that smells fish-ai..
It’s impossible for me to read the word Jaguar and not “listen” to Jeremy Clarkson saying …the Jag.