Hi all, this is my first post on here and I'm asking for help!

I'm hoping that someone on here might be able to point me in the right direction with a recurring fault on my wife's pride and joy, her 1998 XKR.

We have had it for 4 months now and it is a wonderful machine apart from one thing: every now and then a message "restricted performance" appears on the dash and the all that fabulous power is gone. It has been in and out to the garage that we got it from - I can't fault them in their efforts and they are well respected Jag specialists but it's time to look for any ideas from owners.

I'm inclined to suspect an electrical fault but I haven't a clue where to start looking for it.

The car has 84,000 miles on the clock, the engine was replaced at some point and it was unused in the garage for about 8 months before we got it. It had a service about 1,500 miles ago at purchase. It did have a misfire fault that caused high emissions on one side but that has been sorted without affecting the 'restricted performance" fault.

I don't have an OBD reader - is there a data logger version that will record intermittent faults?

So, any ideas will be very much appreciated!

Cheers, Dave.

 

You really have to get a Code Reader. It will help you (and us) locate the problem area. Many Codes will not clear immediately, even if the fault goes away.

 

Take it to AutoZone and get the codes read.


Mark

 

Or a UK equivalent if they offer that service.

 

Thanks for the replies! Is there a list of decent OBD readers anywhere? There's no point in me buying one with a reputation for not being up to the job on a Jag.

 

https://www.jaguarforums.com/forum/g...-%2A%2A-33347/

 

I bought a Memoscan U480 off ebay for a tenner, works great on my 2005 XKR, even tells me the VIN.

 

i was getting that code alot. look at the knock sensor connectors mounted on the thermostat housing on either side and unplug and spray with contact cleaner and then ask someone that has a scanner to clear the codes if it doesnt clear up (most places in the usa do it for free). the misfire triggered the restricted performance.

 

I would also recommend checking the fuse on the aux.cooling pump circuit for the supercharger intercoolers. Not sure what fuse number it is but your owners manual will have the information. A non functioning I/C coolant pump will cause that type of symptom without throwing codes.

 

Thanks for all the tips guys! I'll order the U480 scanner and see what it comes up with.

 

Sooooo.... the U480 isn't talking to the car.

I'm getting a "linking error" message. Any ideas? Is it just not compatible with a 1998 XKR? Or, and I'm pulling at straws here, could there be an issue due to the historical engine replacement?

I got to drive it myself the other day (it's her daily driver) and there is a definite misfire which precedes the error message. It starts fine from cold and then gradually starts to miss in a regular pattern until the error message appears. When I restarted it after about an hour, it then behaved itself for the whole journey home. The route was all light duty suburban driving, about 45 minutes each way.

In other news, the electric water circulation pump under the air cleaner is giving up. I've read about an upgrade to a Bosch pump - is this the preferred option or is it better to go OEM?

 

It should link - try any other modern car withing walking distance -

 

It is obvious that your Restricted Performance is a temporary fault if the garage is unable to get a code using an OBDII code reader. A fault must occur 2 times within a given amount of time to set a hard code in other words a real fault. A temporary fault could be caused by many things like O2 sensor, knock sensor and a small vacuum leak but not limited to. Get yourself an OBDII code reader and you do not need the best or the most expensive my pocket one cost me $39.00 in the US or barrow one. Plug the code reader in (make sure in is reading the car) and check the given codes you should have a P1111 and that is OK. Now that it is plugged in drive the car like you would any other time until the Restricted Performance comes up. When it does the code reader will capture the temporary code and when you get it write it down and then post so we can tell you what it is. When the car is not driven unplug it because it will continue to draw power.

Guess work can cost time and money!

 

I'll have another go at it this evening. Don't worry, I have no intention of replacing parts without knowing I have the correct diagnosis. I have the time to check connections and resistances but a working OBD is going to be far quicker. I also have a 21 year old Toyota Hilux Surf as my daily and a 31 year old Fiat X/19, so I am familiar with pursuing faults .

 

IN regards to the intercooler water pump, I've upgraded with the bosch, you will need to mildly modify the bracket as it's a tad bigger. Also splice in the elec connector from the orig pump. But good luck with finding this problem. Sometimes mine old obd2 doesn't connect and I have to disconnect, turn off car etc. my current reader is fine

 

[QUOTE=dhog4n;1038821]Sooooo.... the U480 isn't talking to the car.

I got to drive it myself the other day (it's her daily driver) and there is a definite misfire which precedes the error message. It starts fine from cold and then gradually starts to miss in a regular pattern until the error message appears. When I restarted it after about an hour, it then behaved itself for the whole journey home. The route was all light duty suburban driving, about 45 minutes each way.


I had the same 'restricted performance' message appear on my recently purchased '99 XK8 that had only averaged about 200 miles a month for the past 6 years and had not seen any highway driving in years. Given your mileage (83,000 I believe) it's very possible that you need to give the mass airflow sensor (MAFS) located in the intake tube shortly after the air filter a thorough cleaning. Their is a readily available spray cleaner that you can purchase at any good auto parts store.

There is also the distinct possibility based on your above description of it not starting to misfire until after it has been warmed up that you have a bad plug(s). A normally missed possibility because of their general reliability is worn or incorrect spark plugs. Again, with your mileage they could be badly eroded if they're the originals or they could be, if previously replaced, the wrong heat range for your engine which would cause them to start misfiring more regularly as they became hotter.

Both of the above are easy DIY jobs. Also think about the possibility that the throttle body has become dirty and isn't flowing enough air for the demands being placed up the engine. That can sometimes be fixed by an application of TB cleaner (also available in a spray can) and/or a couple of consecutive fill-ups with a good injector cleaner such as Techron which is available in bottles sufficient for 20 gallon fill-ups.


Keep us posted for our own continuing education.

 

Mine had sort of the opposite problem. It got the RP code when cold and went away after driving it a bit.
Whoever installed the plugs didn't put any dielectric grease on the boots. In humid weather moisture had gotten trapped under the coil cover plate and at night it would condense on the underside of the cover and drip down into the coils and plug wells. The heat of driving it would chase the moisture back to the cover were it was somewhat trapped and couldn't completely dry out. Taking the covers off and leaving the bonnet open on a sunny day cured it. When I change the plugs the boots will get greased.

Dave

 

Now there's a bit of ancient history. Back in their day I toyed with buying an X/19 as I had previously owned an 850 roadster and had a lot of fun with it. I'd also owned an Opel GT which was an unusual car in that it's 3rd gear was exceptional long geared and would take the car, as I recall, almost to 100mph before running our of revs. It was truly a passing gear. I'd like to see some pictures of your X/19.

 

I've owned 2 of those damn things myself, an 83 and an '86...I will say this, I bought a brand new Miata in '91 and I wanted the X/19 back.

I had the Citroen version of your Merak, a '72 5 speed SM. Only car I ever owned that cost me on average $5k a year to keep on the road. and it only had 33k miles on it when I sold it. Was fun to drive though.




Dave

 

Just to tie off this thread: we were away for a week at the start of the month so we took the opportunity offered by the garage we bought the car from to let them spend a bit of time over it. To anyone in Ireland, I can't recommend them more highly - they really have gone out of their way to help us with the niggly problems. Their labour costs on this would be ridiculous if they had actually charged for it.

The garage owner used it as his daily driver for the week and was able to replicate the fault and isolate it. It turned out to be a dirty connection plug to the coil on cylinder 8. Cheap on parts, heavy on labour!

I have also replaced the intercooler water pump with the upgrade Bosch pump (before it went back to the garage) and that seemed to help with the misfiring, which suggested heat was a contributory factor. The reason for replacing it was excessive noise and vibration from the old pump (it was significantly louder than the 16 year old engine).

The remaining niggle is the failure of the OBD reader to work. I tried driving the car with it plugged in and the dash showed new faults which disappeared immediately when the unit was disconnected. Some sort of feedback problem, I guess. This is not a major issue for now but I would like to resolve it so that I can check for codes in the future.

In short, we are happy campers!!

By the way, the garage in question is Yomac Cars, located in Dublin Industrial Estate, Glasnevin, Dublin, Ireland. Google will throw up a link if you want to search for them.

Thanks to everyone who commented in this thread, it was genuinely helpful and much appreciated.