This is my second year owning this 2001 XJ8 (4l). I live in the Baltics, and as some of you may know, there are countries where people install biogas supply units to run their cars on biogas. I acquired this car with an engine gasket that had exploded due to such modifications, and the previous owner had replaced the engine with a donor engine. This is where all the problems began.
I am quite desperate to find a solution to these electronic issues, but I still want to give it a try. If the gentlemen of this forum cannot help, I am sure no one can.
My car's VIN is SAJDA14CX1LF24348 (originally a US car), and as I mentioned before, the previous owner swapped the blown engine with a donor engine from another car with VIN SAJJHALD4CR829747. The issue, as discovered later by my electrician, is that the engine was the only part taken from the donor. After the engine was replaced, electrical issues appeared immediately—most notably the well-known engine check and "restricted performance" errors.
The previous owner replaced the engine coils and later the engine control unit (ECU), but that didn't solve the problem. He also purchased another throttle from the UK, supposedly programmed for the swapped engine. Despite these changes, the engine check light and dashboard errors persisted. The car does not go faster than 130 km/h, and if you accelerate aggressively, it starts to "jump," as if it accelerates quickly and then suddenly restricts the acceleration.
When I got this car, it had not been used for around two years. I also noticed that the transmission behaved poorly due to a lack of maintenance. There were other issues like the central lock and a few other minor problems. The major repair I undertook was replacing the transmission (from another donor car) and changing the tensioners and chains, as the engine sounded bad and there was an error indicating a damaged chain.
As the electrical issues persisted, I found an electrician to diagnose the problem. After waiting six months for him, he was quite surprised by what he discovered. To sum up, he told me the following: with parts from different donors (engine, throttle, coils, engine control unit, and transmission), it is impossible to set everything up correctly. All these parts are so heavily electronically programmed that they need to come from the same donor to work properly.
2001 XJ8 with swapped engine
Therefore, I received the verdict that it's impossible to repair my car. Indeed, it doesn't make sense to replace all these parts, especially since the car's body isn't in great condition either.
Currently, the car runs as described and appears to have a major throttle issue. The throttle doesn't work properly—it opens too fast (scanner shows this). When I put it in reverse and accelerate, it jerks back so hard that it's frightening. If I accelerate too much, the rear wheels spin as if the car were chip-tuned for more power (though this only happens when starting to move; continuous acceleration leads to the "jumps" I mentioned earlier).
I've shared my predicament with you, gentlemen, and if any of you could offer some advice, I would really appreciate it. The long XJ has been my childhood dream, and I don't want to give up on it so easily. Deep down, I understand my electrician's point, but perhaps there is still some hope and light at the end of this tunnel?
Max
the donor engine number could confirm it is the correct one for the car?
The trans sounds like it needs a rebuild or at least a trans-go valve kit, as you're suggesting the classic 'hard shifts' into reverse - the bang into gear at higher revs is a valve sticking in the trans, against a wear ridge. This leads to a pressure spike and failure of a circlip holding the A drum, once that goes it's a new trans or rebuild.
Your electrician is correct in that the ECU's can only be swapped with the correct software - a Canbus system that can read and rewrite to the cars memory, high end OBD readers have this capability, you'll either need dealer level WDS/IDS or very good aftermarket for reprogramming. Thing is, why was the original ECU swapped and can you get it back in the car? The donor engine doesn't need a donor ECU, just all the sensors plugged in.
A simple Bluetooth OBD reader like the ELM unit plugged in under the dash will give us codes that can help pinpoint engine faults, the software mentioned above will give a lot more info.
There is a throttle adaptation procedure, and a throttle cable adjustment guide within the forum, these 2 things you can carry out now - they are fly by wire throttles, firstly confirm the throttle cable has little slack, then perform a 'hard reset' - leave the battery disconnected and go for a coffee. Battery (12.5V+) back on. Start the car and let it perform the recalibration, high/low idle and settle, leave it to idle for 5 mins.
A few suggestions to get on with. I'm sure other members will come in with advice being a US supplied car.
I agree highly with Bob and Sean. The flexplate is different and the lack of a camshaft sensor and trigger wheel on bank 2 along with a different bank 1 cam trigger wheel that the sensor reads. I’m going to assume that the original engine is long gone?
You will need aj26 sensors and probably throttle body
good electrician can solve this with the right amount of $$$
However the transmission also is another problem
I think the better choice is keep it as car parts and get xjr or another low mileage xj8 in good condition but it's all your choice
Thank you for your comments. From what I heard from you, I think it's better to keep this car running "as is". It just does not worth spending so much on these issues, I doubt I will also find any workshop ready to handle it.
Yes, original engine is gone, what I do have is only previous engine control unit module. Previous throttle is gone, as well as I don't think I will be able to find any electrician to maintain this specific car.
There are not much Jags in Latvia, I am afraid trying to solve this will only make me lose money. I got this car for 2000 eur with all these problems, previous owner told me he spent 5000 eur for the engine swap and other minor issues.
By the last year I owed it I have spent 3500 eur for sure, and I know it will keep on asking for more.
Unfortunately, there are no big selection of these cars in better condition.
Thank you for your comments. From what I heard from you, I think it's better to keep this car running "as is". It just does not worth spending so much on these issues, I doubt I will also find any workshop ready to handle it.
Yes, original engine is gone, what I do have is only previous engine control unit module. Previous throttle is gone, as well as I don't think I will be able to find any electrician to maintain this specific car.
There are not much Jags in Latvia, I am afraid trying to solve this will only make me lose money. I got this car for 2000 eur with all these problems, previous owner told me he spent 5000 eur for the engine swap and other minor issues.
By the last year I owed it I have spent 3500 eur for sure, and I know it will keep on asking for more.
Unfortunately, there are no big selection of these cars in better condition.
I appreciate your help, thank you once again.
You're welcome I support your decision this looks like will cost a lot and it might not be solved not worth it if it's runs okay who needs more than 130km speed however it May show other problems I hope you have another car since this might stop for different reasons . Good luck
It's true....these ladies were designed with all the supporting sensors in an
integrated fashion. Just ask any of the forum members who have done LS
swaps and they will confirm that to be true. It would seem your only rational
option. at this point, is to continue the "band-aid" approach with the knowledge
that some time in the future a band-aid will not fix it.
I still have this car running and now I have another issue I need help with. This year, I failed to pass the MOT, and the inspectors told me that the car's bottom sides were badly rusted and needed to be rewelded. Since this is a dirty job, I had a hard time finding a proper welder. After some complications, I finally found someone who did the work. However, when I tried to pass the MOT again, it turned out that the CO2 levels had skyrocketed to between 2.3 and 3.1. (and before welding works - it was between 0.000- max 0.010 (at 2500rpm), so I have a clear picture of before-after).
I struggled to diagnose the issue until my father’s friend, who is an experienced electrician, suggested that when welding is done on the car, the battery should be disconnected. Otherwise, all the oxygen sensors could be damaged, leading to improper CO2 readings. Of course, the battery wasn’t disconnected during the welding, and extreme heat was applied to the entire bottom of the car. Now I believe I need to replace all the lambda (oxygen) sensors.
So, my question is: are the sensors I found on eBay suitable for my 2001 XJ8? I know this car has its fair share of problems, but I need to pass the MOT and fix the CO2 issue. If I don’t sell it, I’ll continue to enjoy driving it, because even with these challenges, it still brings me a lot of joy.
Thank you for your attention and I appreciate your help.
With no codes you really don't know what's wrong? Do you have O2 codes?
Your symptoms can come from many sources and that's precisely why you must follow the codes.
Can you check for codes and post back? No problem changing O2 sensors if you need to but I doubt very much the welding caused this. Years ago we were all warned that batteries must be disconnected or all the computer stuff will be blown out when welding on the car. It just did not happen. Is it possible? Well sure! It is a good practice to unhook the battery? Well why not?
You need to get the part numbers first or you will be chasing your tail again? So from that auction get the factory part number and then go to a Jaguar on-line parts dealer and check if that part is right for your car? The parts are all driven by the last 6 digits of your VIN. You just can't trust the sellers because they are selling many parts and have no idea what's what.
Quick tip? If it happened after welding are you sure the guy did not burn up some wiring under the car somewhere? This sounds WAY more likely to me. Especially with what I know about welders! So before you do anything get that car in the air and make a though inspection just to eliminate damaged or burned up wires.
Thank you for the replies. The result was as follows - I sold the car to the guy who has replaced O2 sensors to Denso and passed MOT well. But now he faced issues with transmission, so looks like there are just too much issues to get it on the road.
Now looking for X350.
After the issues you encountered with a X308, it is understandable for the move toward a X350.
There are some very well kept x308s out there that in my mind are far more attractive than the
x350, however you may be so exasperated by your previous encounter, that idea leaves you
cold. I would just keep my eyes open for both and see if you find something that excites you.
After the issues you encountered with a X308, it is understandable for the move toward a X350.
There are some very well kept x308s out there that in my mind are far more attractive than the
x350, however you may be so exasperated by your previous encounter, that idea leaves you
cold. I would just keep my eyes open for both and see if you find something that excites you.
Exactly, I have not left the idea for both. Indeed, in Latvia (and also in nearest Estonia and Lithuania) we have extremely small amount of offers. No cars. Either these are same as mine (I see it in ads), or some ar over MY 2005 and taxed too much. I am also unsure about the right cost of the car, as I can see on Facebook, in US you can get X350 for 3$-5$ in normal overall condition, in Europe these will go for €8k-€9k. Limited offers of cars makes this a real challenge.
Hello, what about spreading the search to near countries in Western Europe? Germany should have a fair amount of cars for example. It might not be the most convenient since you will need to handle logistics and not be able to see the car, but for example in Spain you can at least cars in great body work, likely no rust at all.
At least you will start with a better base than what you have?
Dear Gents, thank you for the advice given, much appreciated. Actually my budget is something around +/- 5k€, but I have not found decent options on mobile.de.
Spain looks a bit too far from me, but I have found this resource, and appears I can find several options there: https://www.autoscout24.com/lst/jagu...age_pagination
Netherlands sells few options with V6 (3,0) or V8 (3,5) with target budget, all more than 250 000km. Is there anything specific in X350's when reaching this mileage?
Wow. I'm taking a motor and trans from a wrecked 2001 xj8 and putting it in a 1999 xj8 Vanden Plas. In order to avoid compatibility issues like Max Den , do you guys think I should I take the computer from the doner car too? (its why Im keeping the motor and trans together)
