I've been lurking for a year or so, but never had much reason to post. Unfortunately we just got to that dreaded time of year.

The fail list looked a bit intimidating, but brake hoses seem reasonably straight forward and front suspension ball joints seem cheap. Brake imbalance is probably that squealing noise, likely a stuck pad. So far, not terrible. The main thing though is the emissions and I was hoping that you insightful gents may be able to give me an idea of where to start the troubleshooting.*

According to the sheet, the Fast Idle Test reported CO of 7.99% with the limit being 0.30% Lambda was 0.788 with the range being 0.970-1.030. HC snuck in at 184 with the limit being 200.

On the Second Fast Idle Test, CO was recorded as 0.00% and HC was down to 3. Annoyingly for some reason the value for Lambda wasn't recorded, but it's down as a fail.

The car has smelled smoky, so no real surprise. What the guy at the garage said was that the exhaust system actually seemed to be in good condition, and that he didn't think it was cat related, more likely fuel/combustion related. His other remark was that the radiator fans weren't spinning so it was beginning to overheat. That said, I've never seen it go above the N line on the temperature gauge. I also would have thought a warmer engine would have improved emissions?

One other thing that I've noticed over the last year of owning the car is the fuel consumption being bad. I know, it's a Jag, of course it was going to be bad. But over the last few months I've been averaging 11 mpg in city driving (moved house, hardly doing any miles now), which seems extra specially bad. I did have a leak in the fuel return line, where it was visibly spraying out, but that's been repaired and I've only gone from 10 mpg to 11 mpg so I think I might just be pissing pure petrol out the exhaust.

I've done a bit of searching and things I've come up with to check include throttle body, mass air flow sensor, lambda sensors. Any other likely causes?

If I get my hands on an ODB2 reader, will it flag up if sensors are dead?

I'd love to try and get her running again, but if it's going to be hideously expensive I can't really justify it sadly. So any pointers greatly appreciated!

* Confession time - I know very little about mechanics and get my HGV/PCV diesel mechanic uncle to do most of the dirty work. Sometimes I'm allowed to wield a spanner, most of the time I'm on tea making duty. Uncle knows what he's doing, but doesn't have experience working on Jags, hence me trying to do my homework first.

 

Could very well be 02 Lambda sensors failing......

They can go to 100,000 miles or fail at 30k, 40k miles so its a bit of a lottery.
My son was having issues with his Vauxhall Astra, poor fuel economy, poor mpg, hesitation when accelerating, juddering and generally poor performance....this at around 50k miles, we replaced the 02 sensors and all was well after that.

Generally these are overlooked as a serviceable item.

They won't necessarily show up on a scan as they can be failing but still perhaps just within parameters if that makes sense?
Still a good starting point, but always worth getting a scan if possible to see if it throws anything up

Re your emissions - Have you considered a Terraclean treatment?

I have no emmisssions problems but am getting my Jag done tomorrow by Warpspeed performance just outside Glasgow, might be worth looking at.

Check out "Wheeler Dealers does an XK8" as they have an issue with failing emmissions, get a Terraclean treatment and resolve the issue, cost arround £80 - £120 depending on engine size

Good luck

Jim

 

Honestly if you were in America. I would do these steps.
Get/rent ob2 scanner (best model u can get)

Change spark plugs to champions
change ignition coils to denso
change valve cover gasket,ignition coil gasket,spark plug tube seals and cam cover gromets
Run sea foam in dirt oil for 200miles then change oil/filter
seam foam in gas (2-3tanks)
Sea foam in intake lines

Change transmission fluid and filter
change final drive fluid


Change brake pads
Ball joints upper and lower

Change the 4 o2 sensors




This will help restore your car. You will be surprised!!

 

Here's the video I was talking about, check out around 6m 30secs


http://www.google.co.uk/url?sa=t&rct...61965928,d.ZGU


Jim

 

A skewed coolant temp sensor will trick the computer into thinking the engine is cold, and thus the 'cold enrichment' fueling is applied even when the engine is warm. This sensor is easily tested. Lacking that, it's inexpensive and easy to replace as a guess.


Excessive fuel pressure due to a faulty regulator can also cause over-fueling/rich mixture. A fuel pressure test would confirm.


Cracked exhaust manifolds can cause a rich mixture condition, as the oxygen sensors interpret the extra incoming air as 'lean mixture' and the engine management system dutifully (but needlessly) richens the misture to compensate.


MAF sensors often respond well to cleaning. You might get lucky! You can buy "MAF Cleaner" aerosols.

Poor grounds/earths and dirty/loose/corroded connections can cause malfunctions anywhere along the line. We've heard many reports of corroded ECU pins (ECU being the brains of the system) due to water leaks into the cabin.



Yes, sort of, maybe.

This early OBD II diagnostic system as used on the X300s is a bit fickle and reluctant to set trouble codes. So, while a code reader (or more ideally, a scan tool) can be very helpful and is a 'must have' on these cars, the readings (or lack thereof) cannot always be depended on.

A scan tool allows you to observe what the sensors are actually seeing and doing. This is much more helpful than simply reading codes (which might not even exist) but it also requires some cause vs. effect interpretation that can get a bit frustrating.


Cheers
DD

 

Yanks (and perhaps others) are not allowed to view it--- "Video not available in your country". Gah! This is taking anti-USA sentiment a bit too far

Cheers
DD

 

@biggies266

my advice ...

print out Doug's advice ... bring it to your uncle

 

Don't know what thats all about Doug?

Try searching google....."Wheeler Dealers does an XK8"........posted here before!

+1 on Plums advice to the OP

 

Doug,

It's payback time. Norri keeps posting videos I'm not allowed to view outside the USA.

You can get round this restriction using something like Tunnelbear to hide your location:

https://www.tunnelbear.com/

Graham

 

That looks pretty cool. Does it work? Any downside? I'm not very 'puter savvy. This old machine I'm using seems to be right on the brink of collapse with problems.....thanks, I think, at least in part, to my brother's endless 'fix it' downloads and machinations, bless his heart for trying.*

I'm afraid that *anything* might put it over the edge.

Cheers
DD


* you can say whatever you want about someone else, particularly a relative, so long as you include "bless his heart"

 

Yes it works. i can view USA videos using it.

However if your machine is on the limits of performance, probably best not to risk it.

Graham

 

That's where I'd start for sure! £15 on eBay will get you a bluetooth OBD2 dongle - there are plenty of android apps that will talk to them, & I'm sure that applies to other OSs too.

My money's on a duff lambda (or 2!), but whatever the cause you'll surely get a clue from looking at your fuel trims, lambda & MAF outputs etc. etc. - as well as being able to pick up fault codes yourself.

 

Tried to contact OP via pm as he's local, offered advice and a few suggestions re a very good Indy that could help with low rates, no response

No replies here either?

Perhaps the issues have been resolved?

 

Probably just hasn't checked back yet - being new, he may not have realised he could expect so much help, so quickly!

 

Thanks for all the replies guys, given me a good checklist of things to work through! I'm glad to see that there's a number of possible causes that don't require me to just set fire to my wallet. I've ordered an OBD scanner, but it hasn't arrived yet. When it does, I'll start working through things.

One thing I did notice on my last trip was that when stopped at lights I was getting quite variable idle speeds - fluctuating between about 850 and 1300. That sounds a bit like the MAF sensor to me, but then again, I know nothing.

Weekend was ruined by the boss at about five to five on Friday, so never had a chance to check back until now. Probably going to be the weekend now. Sadly this means I had to SORN her Since I also don't have a driveway, it meant that on Friday night I parked her in my parents front garden. Didn't get me disowned, but certainly not the favourite child at the moment...

 

Good luck & hope to hear real soon