XK8 problems and Jag Spares NE

[PTR200Jag]

Just wanted to post a note about Jag Spares North East and their exceptional service.
Neville is the man there who talked me through some of my findings agreed with my conclusion and subsequently supplying the part I needed, ordered at around 3.30pm yesterday, Monday, packed, dispatched and delivered to my home by 12 noon today...
That is five star service and some ! Thank you Neville at Jag Spares North East, take a bow !

First a bit of background.
I have had my XK8 since 2014 and in the early days spent a lot of time and effort "fixing" things.

Thermostat tower and associated pipes, Restricted performance issues (and others), blown steering pump, exhaust system,faulty seat modules, CD player faults, missing bits of trim, de-blinging said car (!!) leather interior clean and re colour, and more, etc etc , you know the score !

The car ran great, even went on the Snowdonia Run a couple of years ago achieving 27mpg......... fast forward to December 2016...Engine light on, restricted performance on and off plus others.... MoT time EML still on but goes through the MoT Emissions just.

I then use the car sparingly for the next year until MoT time again, clearing faults as and when with my code reader. No problem with MoT but I know I have a problem code P1646, O2 sensor on Bank 1, pre cat.

I put my hand in my wallet and buy a replacement sensor off the 'net, from a "trusted trader" mate in London. Fit sensor and use car, all lights out but keep getting restricted performance issues. Also the car develops an offbeat tick over plus a "plucking" feeling on take off which can be overcome by booting it ! Also the righthand exhaust pipe develops a lot of rust in the outer shell leading to the possibility of a blown head gasket... or is it.?
I pull everything apart on the intake side checking for hose leaks and a few more things beside.... no codes by the way.
Still no joy and the average fuel consumption is 14mpg and before anyone says it i didn't buy the Jag for its fuel consumption figures but it does illustrate the health of the engine quite vividly. to back that statement up I run a Honda 3 litre V6, a TVR 4.6 V8 and an S2000 as well so I don't expect great mpg !!

I whizz the car up to my mates MoT garage and stick it on the emissions monitor.....green across the board...sensor appears to be working but whilst there I hook up my code reader and go into real time readings... the short term fuel trim is all over the place along with a few other associated readings including fluctuating sensor readings.

Eventually, a few days ago I decide to retrace my steps back to the sensor change... I get the car warm /hot, turn it off and disconnect the new sensor... hot so that the engine doesn't "feel" the change without it. On start up gone is the 7 cylinder feel and the plucking disappears too, the fuel consumption improves to around 18mpg ...

I do a bit of research on the sensor, to discover that there was a change in '98 and again in 2002 to the sensor type. My car is 2002 but the chassis number comes before the change in 2002 (also engine moves to 4.2 just to compound the problem.)

I ring Neville and come to the conclusion that the previously supplied sensor in a "one size fits all" is NOT the correct one ! no matter what the previous supplier claimed. Neville advises that the Denso one is the correct version for my car and not a spurious copy !

This afternoon I fit the new sensor, five minute job, take it out for a test run of around 15 miles on country lanes and 50mph dual carriageways.... RESULT ! Not only has the plucking and offbeat feel gone but it PULLS LIKE A TRAIN
To add to this the onboard computer ( ) tells me the fuel consumption has improved, despite full blooded take offs and a few manual down the gears, in sport mode, overtakes the mpg is now 26.6 !!
I know I will bring that down once some town tootling is incorporated but I can tell now that it will be in the plus 20's once again and that the Jag will get some serious use this Spring.

[J44EAG]

Hello Peter.

Neville the Devil..."Wye aye mon" is a top guy. Highly recommended even if you don`t speak fluent Geordie!

Sensors. Yes, it can be a minefield selecting the right units. Differing threads, cable colours and plug shapes and sizes. I have one here I can`t use for my XJR which was incorrectly supplied by Gendon. They won`t take it back because I`ve opened the packet!

The next one came from Manners. Perfect first time. As I`ve frequently said on the X350 section, buy only genuine Denso and from an OE supplier who has knowledge of the differences and relativity to model years. The Manners phone service was exceptional in this respect.

The reason I had to change a post cat sensor on the near side was because PTJS1 and I found it flatlining. Normally they run at around 0.7V. Paul and I rigged up my Android phone, Torque Pro app and an ELM327 bluetooth chip into the OBD port. Then we set up a trace from both sensors onto the screen. Bingo straight away! There it was for all to see. Near side rear sensor frequency plummeting like a stone. Installed the new Manners sensor and things improved dramatically. Fuel consumption down, reduced stink at the exhaust on cold start, better running etc and a similar trace to the off side unit.

These sensors and there performance are vital to the car. Some may remember an MOT issue I had in Feb 2017. The car only just made it through the test due to high CO at 0.19%. Had it been 0.20, the car would have failed. We had to rev the engine for five minutes to get a just about acceptable CO level. Initially I pointed at the 200 sports cats fitted as a culprit. The issue was a constant worry as I feared having a repeat performance at the 2018 MOT. Then Paul and I got the Torque Pro app going which enabled us to watch what was happening in real time as the car was driven. It was then we found the duff sensor. Once replaced, the car flew the MOT this year without any issues at all. Phew! CO now at a rather more acceptable 0.14% and no problem at all at the test.

Here is what we found with the Android/Torque.ELM set up. Note the left hand screen which was the near side sensor trace that would flatline and cause all the grief.No problem at all now.

It is worth noting that if you diagnose a PO430 or PO429 code, the message will probably say something like "Bank B, catalytic converter out of threshold limits". This DOES NOT imply the cat is shot. I just points to the fact that the cat may be out of limits but it is MUCH more likely that you have a Lambda sensor issue.

Hope that helps.

Mike K

[PTR200Jag]

Hi Mike
Interesting that regarding the voltage... "The reason I had to change a post cat sensor on the near side was because PTJS1 and I found it flatlining. Normally they run at around 0.7V."

My "new" version, one size fits all actually showed 0.74 v (bank 1) and the other bank, which are far as I can tell is running fine, 0.09 v when hot.

I haven't had the scanner hooked up yet with the Jag Spares part fitted but will do in the next couple of days... be interesting to see what has changed...
By the way never had any cat codes at all, just the usual P versions of sensor, knock sensor (couple years back if you recall!) associated with it.

[J44EAG]

Your sensor might have just been within acceptable limits and not have been bad enough to cause a full blown Lambda/cats out of limit code. Its much better for the sensor to fail completely rather than be just about acceptable. If its fully duff, its much easier to find!

The scan shown in my post makes interesting interpretation. Accept both sensors never show identical traces and that there is apparently some sort of switch over which takes place from time to time. What you see on my trace is just after a start up. The right hand trace is typically what we are looking for. The left hand trace is less lively initially but then plummets sharply downwards. Sadly I didn`t take a shot of the flatlining. Had I managed that, you would have seen that duff sensor trace bumping along on the bottom of the graph and taking time to get back up the hill to a more plausible 0.7V.

Yes, I well remember you knock sensor issue. We were both chasing slightly different issues during which we had many brain storming sessions. All my problem turned out to be was a rotted 3.3mm ID rubber pressure pipe from the cowhorn pressure manifold to the by-pass actuator capsule! £3 spent at Halfords buys a superior pipe to the genuine part at less than half the cost. You will no doubt remember my resulting "The 19 day glitch" article saga in the X350 pages of the magazine.

It is great we all pool our experiences and fixes. How I wish we had such knowledge available when I first joined the Club some thirteen years ago. Of course the Forum scene was in its infancy and it took time to get it established. Now its a highly useful facility with good guys punching in an experienced input. One day, someone will thank us!

Good to chat again.

Mike K

[mike020150]

There are lots of suppliers for 'universal' lambda sensors. Whether they work well with other marques is not for me to say but this tale just adds to others which support Mike K's assertion that Jaguars need the genuine article to perform as Jaguar intended or as the MoT man demands! Mike.

[richard.whittington]

Hello Chaps
Reading your posts has caused me to feel quite stupid, and full of admiration for your ability to utilise current technology.
I own a 2002 xk8 that seems to drive well, but on average does only 21 m.p.g . I have noticed that on start up, as the engine gets warmer, more steam emanates from the exhaust.
Is consumption normal for an engine that has done 98000 miles and is the emission of steam normal, or indicative of something that requires attention.
I recently took my car to the Jaguar Main Dealer in Tamworth, and much to my disappointment, was advised that because of the age of my car, that they were unable to help.
Kind Regards
R Whittington

[mike020150]

Hi Richard,
Beware of internet diagnoses for cars. They are similar to reading the NHS website where it's all too easy to convince yourself you have some dreaded ailment!
An XK8 used on a long (100 miles+) motorway journey at legal speeds can be expected to return mid twenties or better mpg. Used locally on short journeys, mpg is much more likely to hover around 17/20 and mixed driving conditions will produce anything in between. Cold starts will produce visible steam. It's a by-product of combustion. As long as the engine isn't using water, i.e. it doesn't need regular radiator top-ups, there's nothing to worry about as far as head gaskets are concerned.

98K miles are not a lot for a well maintained Jaguar V8. There are plenty around with double that mileage. A car used regularly, and hence has a few miles on it, will always be better than one which stands unused for long periods. XK8s are meant for driving and are all the better for it! Mike.

[robv12]

nothing to add on the tech side, but re NE Jags, yep, top bloke is woor Neville, great mate too, always likes taking money off me!!

[BrizzleJag]

Hello Chaps
Reading your posts has caused me to feel quite stupid, and full of admiration for your ability to utilise current technology.
I own a 2002 xk8 that seems to drive well, but on average does only 21 m.p.g . I have noticed that on start up, as the engine gets warmer, more steam emanates from the exhaust.
Is consumption normal for an engine that has done 98000 miles and is the emission of steam normal, or indicative of something that requires attention.
I recently took my car to the Jaguar Main Dealer in Tamworth, and much to my disappointment, was advised that because of the age of my car, that they were unable to help.
Kind Regards
R Whittington

I would suggest finding a good independent Jaguar specialist and avoiding the main dealerships as they tend to be only interested in new models.The club magazine normal has plenty of indies advertising.

[richard.whittington]

Hello Mike and Brizzlejag
Thanks for your immediate response to my post, and your sound advise
K Regards
R Whittington

[PTR200Jag]

Hello Chaps
Reading your posts has caused me to feel quite stupid, and full of admiration for your ability to utilise current technology.
I own a 2002 xk8 that seems to drive well, but on average does only 21 m.p.g . I have noticed that on start up, as the engine gets warmer, more steam emanates from the exhaust.
Is consumption normal for an engine that has done 98000 miles and is the emission of steam normal, or indicative of something that requires attention.
I recently took my car to the Jaguar Main Dealer in Tamworth, and much to my disappointment, was advised that because of the age of my car, that they were unable to help.
Kind Regards
R Whittington

Sorry for delay in posting against this but its a faff to have to keep logging into the site (still haven't resolved the issue !)
As a matter of interest now I have done around 500 miles since changing the sensor to a Nev Special and the car is running great ( where is that lump of wood ) NO jackpot lights on the dash as yet
My XK8 has done just over 88k and for the last year and a half been plagued with seemingly unconnected dash lights and legends such as "restricted performance".... Just the change of this O2 sensor appears to have fixed it all !

One other thing to note was that whilst I had the spurious sensor in for only a couple of months the exhaust trim pipe on the affected bank has a lot of water vapour followed by a rusting of the inside of the trim... the other side was unaffected in this way.
I have to presume that the sensor was cocking up the fueling enough to produce excess "liquid" but NOT to throw any warning lights or codes such as weak / rich fueling etc.
Since the change to the correct sensor not only has the engine cleared up its hesitancy problem but the rust has disappeared off the trim, indicating that all is well (or at least as well as can be expected !)

Regarding fuel consumption, I regularly now get 22/24mpg with mixed driving , town / country roads. In town I can be down to 20mpg quite easily but as much as 30mpg on the 50mph carriageways over a few miles. Certainly a MASSIVE improvement on the previous 14mpg I was getting!!!

[mike020150]

It's great to hear a good news story! Mike.

[PTR200Jag]

It's great to hear a good news story! Mike.

Happy Jag bunny at the moment !
It's wonderful to be a able to drive it again without getting the full roll of jackpot lights and yet not finding the central console full of coin !

[J44EAG]

Peter,

I`m pretty certain you can get even better fuel economy figures. I`ve batted on quite a bit about what occurred after I had a Terraclean done followed by several sessions with either Cataclean or even better, Oxy Cat. Recently I fired three cans through the XJR in quick succession followed by two cans of Liqui Moly injector cleaner......Boy, did those two products help clean out the muck and improve performance and economy! Exhaust tips are now completely clear of carbon fouling.You might also have seen the results of the EDT session I had done on Monday in my Engine Decontamination thread. A mega result with even more grunt coming back on line with 35.3mpg being realised at 50-55mph in sixth gear.

Here is what I said about the process on Trustpilot. The treatment outcome was nothing less than awsome! An egg cup full of varnish and gum removed from the engine and the car became a hooligan!! I now regard the EDT treatment as the best tune up treatment ever!!! https://www.trustpilot.com/reviews/5a78 ... 0e9c227772

Hope that is of interest.

Mike K