Before you try anything more extreme, try taking off the PCV housing and shaking it to check if it works. If it rattles, it's fine, if not that means there's oil sludge inside that gunked it up and you can rinse it with carb cleaner before putting it back on.

I had the P0171 code off and on for over a year that I hunted to futility until someone advised about the valve and I haven't seen it since. Apparently it's a common auto fault that usually no one thinks about.

Also, for a 'new' X350, you want to check on whether the thermostat housing and coolant tank have been replaced or not. If not, it's almost certain they're brittle or falling apart by now.

 

Hi Guys,

Thanks again for this useful idea. I just took the PCV off and you're right. It's gunked up. It's soaking in carb cleaner now and I'll put it back, clear the codes and see what happens.

It did just throw P0171, P0174 and a new P0101 code. The freeze frame data from the P0171 code is:

Parameter Description Results
Fuel System 1 Status Closed Loop
Fuel System 2 Status Closed Loop
Calculated LOAD Value 34.90 %
Engine Coolant Temp 199.40 °F
Short Term Fuel Trim - Bank 1 -0.78 %
Long Term Fuel Trim - Bank 1 19.53 %
Short Term Fuel Trim - Bank 2 -2.34 %
Long Term Fuel Trim - Bank 2 18.75 %
Fuel Rail Pressure 47.42733 psi
Intake Manifold Absolute Pressure 22.50 inHg
Engine RPM 2,059.50 rpm
Vehicle Speed Sensor 78.91 mph
Ignition Timing Advance #1 Cylinder 38.00 °
Intake Air Temperature 91.40 °F
Air Flow Rate Mass Air Flow Sensor 5.22 lb/min
Absolute Throttle Position 24.31 %
Time Since Engine Start 1217 sec

Thanks for everyone's help as always, really kind of you.

Chris.

 

Hi folks,

OK, so on Thursday evening, I changed the fuel filter. By the looks of it, it was so rusted and a Jag filter, it was probably the original one from 2006. I took off the engine side pipe first - no fuel. Then I took off the tank side pipe - it must have sprayed a pint of fuel at me. Good job I had plenty of rags to hand! With this kind of back pressure on the filter it must have been heavily blocked.
Put the new one in, started the car, clouds of blue smoke everywhere, but it settled in to a very smooth idle - more so than it's ever done before. I drove it 250+ miles yesterday and some more today, definitely less throttle required for the same performance. Still no repeat of the codes. Blue smoke on cold starts, but I'm guessing that's all kinds of gunk built up in the fuel lines/tank that haven't been allowed out in years. I put a can of Sea Foam in the fuel tank, hopefully that will help clean any other contaminants out over the next few tanks of fuel. There wasn't any smoke prior to the filter change and no oil loss at the last 10,000 mile change (Mobil 1), so that's not what's causing it.

I'll cross my fingers that this was the problem and it stays gone.

I also checked the thermostat housing and expansion tank. Both look pretty new so I bet they were recently changed.

Thanks.

 

SO!, I took off the PCV and cleaned it, popped it back on and ran it, P0171 had gone to be replaced with P0131 and P0031, Bank 1 O2 sensor codes and another P code, cant remember the actual number but it was to do with catalyst efficiency below threshold, cleared those and went for a drive, 131 and 31 came back, and 171 was a pending code.
got it up on a ramp and took out the upstream O2 sensor, used a thread chaser to try and restore the threads on the Cat and put a new O2 sensor in, tied everything up, cleared all codes, and ran it up to temp, bank 1 short term trim immediately dropped to -14, long term sat at 19.5 for a while then dropped slowly, took it out for a drive and noted bank 1 and 2 trim values almost exactly the same, all below double figures and into minus.
Parked up and left it for a half hour, then off again. bank1 had a pending of P0171, and initially the trims were way back up, but came down again after moving off.
I will keep an eye on them but it's looking good so far.
So in summary,
checked for air/vacuum leaks, couldn't find any
checked for exhaust leaks, couldn't find any
cleaned PCV , original P0171 code was replaced by P0031 and 0131.
Replaced Upstream O2 sensor on Bank 1, codes gone.........for now!

 

Well, so far so good, I do get the odd pending catalyst fault code, but it hasn't gone confirmed "yet".

3 days I think it was with no Engine management light on, and I was a happy bunny, then out of the blue, the ABS and DSC lights cam on, with a yellow warning light in the centre dash and messages about Cruise and DSC being unavailable and ABS Fault. And the engine management light popped on for good measure.

So I read the codes and had C0037, left rear wheel speed sensor, P0500 Vehicle speed sensor malfunction and P0501 Vehicle speed sensor range/performance.

I cleared the codes and all was fine for a couple of days, then they came back, so I will need to get a look underneath and see if it's just dirt on the reluctor ring, or a bad sensor or wiring.

on another note, I had a wee surge of boy racer the other night and kicked it from about 40mph on a straight bit of road, in the rain, there was a heavenly, V8 roar and the back wheels started to spin, but it stayed straight and true. I love this car.

 

Glad to hear you're having fun with it. I have to say I love mine. The big cheesy grin I get when I floor it makes it all worthwhile. Quicker in a straight line, but not quite as much raw fun as my John Cooper Works Mini, but at least I'm not exhausted after 5 hours behind the wheel.
After apparently killing my PCV by soaking it in carb cleaner for 15 minutes, I replaced that on Monday and the clouds of blue smoke at start up seem to have disappeared. Apparently a dead PCV will do that - lesson learned. The car managed to burn a gallon of oil in 3,000 miles having lasted the previous 13,000 without losing a pint. I did change all of the plugs and they were nice and clean.

It's still throwing P0171 and P0174 codes, but I have ordered new O2 sensors that will be here tomorrow, so I'll get them on and keep my fingers crossed.

I'll let you know if it works.

 

Check fuel trims before you do (and again after, once relearned).

Parked. Hot engine. Idle LTFTs.
Then rev to 2500 or so and measure again.

On a lot of jags those codes are not O2 sensor faults.

 

chrissleath, I know exactly what you mean about the Mini Cooper, the Wife has amk 2.5 MX-5, So much fun and you can really throw it about, but any longer that 3 hours my knees and my back lock up and I'm pretty much stuck in it.

The O2 sensors are not too expensive, but JagV8 is right, it's still a pretty penny to just throw at it, if it's not going to fix it, I pretty much doubted that it was mine that was bad, but almost as soon as I changed it the fuel trims started to drop and now all is good, With both codes showing, I would def look for an air or vacuum leak first, as mine was a bank 1 code I kinda expected it not to be a leak, as I assumed that if it was, both codes would show, unless it was a deep down leak in the bank 1, which could have been a gasket and a pig to sort, luckily, with the advice from the guys on here I got it sorted.

I have just ordered a solar powered 15w charger which I intend to hook up every time I park up as I did notice the other day after it sat for almost a week that it was a tad sluggish to start, I know low batteries can cause all sorts of electrical gremlins to show up and I actually had no power steering till I switched off and on again after I let it run for about 5 mins. I am going to stick the battery on charge just to be safe, then hook up the solar charger and pop it on the dash, whenever I park up, hopefully it helps.

 

Thanks Gents, that's interesting to know.

Mine started as a code only on bank 1, it wasn't until I switched the sensors over that I saw codes on both sides. Hopefully that's an indicator that it is the sensor.

So the new O2 sensor showed up in the post when I got home last night. I fitted it to bank 1 and started the car. It was OK for a few seconds, then a rough idle, then when I tried to move, the check engine light started flashing and it went into limp mode........hmmmm. I stopped the engine started it again and it was OK and drove off. Then when I tried to accelerate, it went into limp again and threw 10 codes: misfires on every cylinder on bank 1. I reset them, tried again, drove for 5 mins to let it settle and calibrate, but the same happened again (without the limp mode). At this point, before I did any serious damage, I took the car home, changed the sensor back to the old one and the misfires all vanished immediately. So, is the new sensor faulty? Should I have changed the pair? Or should I have bought the original Denso one instead of the new Bosch one I got on eBay? The only data I managed to gather when the new sensor was in showed:

Short Term Fuel Trim - Bank 1: 7 %
Long Term Fuel Trim - Bank 1: 19.2 %
Short Term Fuel Trim - Bank 2 -14.5 %
Long Term Fuel Trim - Bank 2 18.7 %

The car had obviously tried to adjust for the new sensor, but couldn't go far enough.

brian5, where did you buy your sensor from? Was it the dealer? I'm going to get a price from my local one today. If yours is cheaper, I'm going to wait until I come back to England from the US in a couple of weeks and get it there.
The other thing about the Mini that you probably don't suffer with is that here in Michigan we have dreadful roads. It's like an obstacle course in the Mini to avoid the pot holes and expansion joints or I get shaken to bits!! :-)

Any thoughts would be welcome.

Thanks.

 

That all sounds very strange, I do seem to remember getting a misfire code and a catalyst below threshold after changing mine, but no limp mode, or anything, I didn't take mine on the road until I had ran it up to temp and then I cleared all codes and went for a spin.

I don't like buying sensors off Ebay, especially O2 sensors, some Ebayers have no idea what they are selling. I got mine from a local Motor factors I deal with all the time, It was a "Blue Print" O2 sensor part number ADJ137024 price to me with my discount was £90.

I don't mean to sound like I'm calling you thick or anything, but make absolutely sure you are changing the correct sensor, I speak from experience, lots of head scratching, then going back to square one and having a Homer Simpson moment. there are 4 sensors 2 on each bank, 1 between the engine and the Cat, 1 between the Cat and the Tail pipe. Sitting behind the wheel, Bank 1 is right, Bank 2 is Left. The price of the 2 sensors is markedly different with the rear sensors being about half the cost of the front. I have also heard of code readers giving wheel codes for ABS faults, like telling you it's left rear when it's actually right rear, so anything is possible. I have also used a code reader that screwed up the entire ECU and I had to reset everything, So it Wouldn't hurt hook up a second code reader and see if the codes differ.

As for roads.....I live is SCOTLAND, Here we have small sections of road between potholes..........

 

You know what, "thickie" is my middle name. :-)

You've got me thinking now......I read that bank 1 is on the driver's side, but of course that's on your car, not mine over here in the good ol' U S of A........DOH!! My driver's side is bank 2.

So guess what? Yep, I changed the wrong one out. That goes a long way to why I saw the trim readings I got. Still doesn't explain the misfires on cylinders 2, 4, 6 and 8 other than that's the same side that I put the new sensor. I did get the same "catalyst below threshold" that you saw, but it cleared.

I called the place I bought it from yesterday and they agreed to send a replacement. So, before I ask for a refund and send both back, I'm going to change both and see what happens with a matched pair (although there's no guarantee they'll be compatible with the downstream sensors).

I also called my local Jag dealer and apparently theirs must be gold plated as they wanted $350 each for the upstream sensor.

I have to agree with you, I rarely buy parts from Ebay. There's a couple of good stores over here that I normally use, but they wanted a lot more than the $45 I paid. On the other hand, you do get what you pay for.

The replacement sensor should arrive by the time I get back from Britain in 2 weeks so we'll see what happens then.

Thanks again.

 

Sometimes it's a simple thing like that that causes so much trouble. In the UK the motor trade used to use the terms Nearside ( nearest side to the Kerb while you were driving ), and Offside, which was basically the side furthest from the Kerb while you were driving, as we moved more into Europe, they dropped those terms for left and right, as in Mainland Europe they drive on the right, and in the UK we drive on the left, so nearside and offside just confused the hell out of everyone. The solution was, as you sit in your car, left is left and right is right, that way, it doesn't matter if you have your steering wheel on the wrong side (left), or the aptly named RIGHT side, it's still left for left and right for right. Also, The Upstream sensors were £90 each, £45 was the price I got for the downstream sensors, again, these terms could be confusing to some, it relates to the direction of flow of the exhaust gasses flowing from up to down, engine to tailpipe.

Your misfires "could" be down to the fact that the ECU has tried to rectify the overfuelling by cutting back too much and not supplying enough fuel to ignite, and therefore causing a misfire, once the trims level out the misfires "should" disappear

 

Pic of banks
https://www.jaguarforums.com/forum/a...8fireorder.jpg

 

The greatest probability is that it is a vacuum leak. I have (like many others) have chased this code around using various rationals but it usually comes back to a vacuum leak.
I found mine by starting cold and using a flammable spray such as carb cleaner or starting fluid. I used starting fluid and could hear it detonating in the cylinders as it sucked through the leak (gasket between plastic and aluminum intake manifold pieces). There is also a vacuum hose in the rear of the intake that goes to the brake booster. I had some dry o-rings that were contributors to the problem.

Best of luck.

 

Hey guys,

So, here's a quick update on mine. I did get the replacement sensor which was better than the first one, but it still caused issues and led to an uneven surging acceleration. I have finally concluded that I needed to use the original one from Denso.
I bit the bullet and ordered one, changed it over and it has given identical codes and identical trim readings as the old one. The only thing I could draw from this is that it really has nothing to do with the O2 sensors and the original ones are OK.
From others' recommendations, I have looked this weekend to see if I can find a vacuum leak. First, I used a trick a colleague from work suggested to use an incense stick and move it around all of the seals with the engine at idle to see if smoke is sucked in anywhere........nothing. Then, I managed to track down my old Halloween smoke generator, removed the plastic intake between the MAF sensor and the aluminum intake on top of the engine and connected it via a piece of hose and blew smoke into the intake body to see if I could see smoke coming out of anywhere......again, absolutely nothing. If it is an intake leak, it's very minor. The only thing that still makes me think it could be a leak is how low the MAF is reading, 3.5 - 3.9 lb/min at about 25% throttle.
I know it doesn't fix the root cause, but I can make it stop showing the code by reducing the airflow through the filter. The frequency of it triggering the code went up when I put a new filter in couple of months ago. I have just covered up half of the filter to deliberately reduce the flow and see if the code stays away. If it does, it has to be some form of vacuum leak, unless anyone's got a better idea?? It's still running great and I'm still averaging 23mpg.

Thanks everyone.

 

Once it's settled, i.e. re-learned the sensor(s) in there, post #27 will show whether it's an air leak. It may or may not be at this point.

 

Hi there,

Continued thanks to JagV8 for all your help, it really is appreciated. Hopefully the below will enable you to help a little more.

It's been a few months since my last post, mainly because I didn't have access to record real time data, but also because I've had to change the clutch (twice) and DM flywheel in my JCW Mini. My son passed his driving test in Sept and he's driving it regularly now. Despite my careful training of him, 2 weeks later the clutch was slipping so I completed the mammoth job of a clutch/flywheel change. Six weeks and 2,000 miles later, he went through another one. I've changed the clutch again and he's been relegated to driving the Jag, little swine. I'm driving the Mini for the next 3,000 miles to prove it's him.

Anyway, back to the issue on hand with my 2006 XJR. I now have an OBD2 code reader that can show real time data (thanks Santa!!).

At idle (after 15 minutes driving to warm it up), the readings are fairly consistent, but STFTs are fluctuating at:

STFT B1 3.1 - 4.7%
LTFT B1 9.4%
STFT B2 4.7 - 7.0%
LTFT B2 7.8%

At 2500rpm, the readings are fluctuating quite a bit with my foot and the revs held pretty much steady at:

STFT B1 -6.3 - 5.5%
LTFT B1 14.8 - 16.4%
STFT B2 -3.1 - 5.5%
LTFT B2 15.6 - 17.2%

A couple of other things to note:
- A couple of months ago, I took the MAF out and cleaned it with MAF cleaner.
- The car is now throwing a P0101 code too. (MAF circuit range/performance)
- It has also started "hunting" during warm up driving (before normal temps reached). At 50mph, it fluctuates between 1,600 and 1,700rpm. I fear cleaning the MAF has knackered it.
- I replaced both downstream O2 sensors with new OEM parts. Made no difference at all.

Any suggestions you've got would be very welcome.

Best Wishes,

Chris.

Anything you

 

Ouch - re the mini etc!

As the LTFTs get worse, it suggests something like poor fuel flow (blocked filter, failing pump, bad fuel pressure sensor), a MAF issue (dirty, etc) or an exhaust problem (bad cat, exhaust leak, etc).

You don't appear to have the rather more common air (into vacuum) leak.

 

Thanks again JagV8. Very kind of you to reply.

In advance of your reply, I did go ahead and order a new MAF sensor, which I'll change and see if it has any effect. Troubleshooting by trial and error...………..

Also, and apologies for not mentioning this the other day. Last winter and now this winter, it does have a sporadic tendency to idle low and almost sputter at starting, then pick up and drop to a steady idle. It went away during the summer, but has returned. I can stop it from doing it by turning the ignition on, waiting 2 seconds, then starting. I dismissed it as a winter fuel issue. Jags are known for having issues with the winter fuel blend here in the US and as it went away in the spring, I put it down to that. But, I did have a nagging thought it may be a fuel flow issue with it obviously taking a couple of seconds to build initial pressure when primed. Having changed the filter, it's probably not that, but I will change it again to be safe (as it's cheap). I guess the next thing after that is to take it to a guy not too far from me who has worked on a lot of Jags and have him check the fuel pressure from the pump. If that's low, then I guess I have to bite the bullet and change the pump. I did look through a few posts and it seems it's not an uncommon issue in the X350. At least it's not a PITA job like my old S-Type where there was no access through the floor under the rear seat!!

I'll let you now how it goes.

Thanks!!

 

If you've already changed the filter it's not likely to be it.

You can probably check fuel pressure either physically or via OBD.