Jag failed its mot!

 

That reads like it could be a failed oxygen sensor. Get the OBD codes read - that sort of thing will log a fault.

 

Might be a different emissions failure but mine once failed cos of a failed coil allowing unburnt fuel into the exhaust

 

Did the ecu pick up the faulty coil with a code?

 

Bet it has an air leak.
Read LTFTs (see below) at idle & 2500rpm (in P will do).

 

Is the Lambda reading too high or too low?

 

Good point. All MoT printouts my mates & I have had for years have had actual readings and been very interesting.

 

Yes, you get precise figures, including the Lambda value, from the National Car Test (NCT) here in Potatoland as well. With most jalopies I've encountered, it seems that in general, high Lambda (probably accompanied by decent readings for CO, HC, etc) indicates a leak somewher (intake/exhaust) whereas low Lambda accompanied by the sort of readout the OP posted tends to indicate a failed/failing O2 sensor and a "false lean" sort of condition.

 

Well i had a good look at his Jag today and there was no fault codes and all 02 sensors working but fuel trims were about 20% on both banks.
I sprayed carb cleaner down below injector rail by cylinders 5 and 6 and no change in engine speed/tone, then i checked all other vacuum pipes and all ok, the rear IMT was a bit wet around the bottom but not leaking air, so i removed a spark plug to find it worn down and the gap about 3mm.
So i then removed the inlet manifold and all 6 plugs were the same and they look like they have not been changed from new! Also had oil around plugs 1 and 3.

Would just the plugs cause the Emissions problems?

 

They would if they're letting enough unburned or still burning air/fuel into the exhaust and then the cats may well also be toast

 

No, I had no codes

 

I forgot to mention that the other check with OBD is that you have P1111 and no other codes. P1000 should only occur briefly e.g. if you've had the battery off and should change to P1111. Otherwise you have fault(s) stopping the car flagging codes because the OBD monitors can't run fully.

 

Thats a good point, i get P1111 then i check the codes on my Jag, but there were 0 in my mates!

 

So you fix the plugs etc then disconnect battery, wait till P1111 occurs and check LTFTs at idle & 2500rpm. And get 4 readings which are?

 

Well i changed all spark plugs and both valve cover gaskets (under manifold) and the bends on the breather along with new inlet manifold gaskets and a new o ring for the rear IMT valve and it passed its mot with no problems!
Also disconnected the battery for a few hours and still no code P1111 and also can't read fuel trims but can see the volts from all 4 02 sensors.

 

failed emissions the other day, no CEL or stored codes. Took it to hennessy jaguar here in atlanta and said that it was fine just to keep the fuel level a quarter above half a tank or something like that, cant really recall, and drive it some. put about 200 miles on it then checked it with my scan tool hooked to my laptop and the evap system cycle still reads incomplete. Where should I start?

 

No P1111 must mean you have P1000 or else codes or a broken OBD tool.

If P1000 it means one or more OBD monitors can't/won't/hasn't run. See codes PDF in stickies/JTIS for details and then by all means come back with an update/questions.

Please remind me which side of M45254 your VIN is, if you do.

 

Is that the only monitor not Complete (aka set)?

Being such a late car you may need to do things I don't know but they will be at least as in the codes PDF (sitckies/JTIS) for the 2003+ cars - see the first 10 or so pages.

If it's only evap, there may be a posting on here (I think) about this from one of the techs. Advanced Search will let you specify evap as keyword and you can restrict to just this forum plus choose Posts then - sorry - hunt for anything helpful.

Evap does need not too low fuel (so not much slosh) and not high (so there IS some evap) and so on. You may need to be below some altitude and so on. Bit of a nightmare.

Your car will have the newer emissions stuff (laws got tougher) so it all has to be exercised.

I dimly recall it needs things like an overnight soak (engine off) but heck it's had it by now!

A couple of tries at a link that may help (same file just 2 ways, they're big but look at the Monitoring stuff):

www.jaguarforums.com/forum/attachments/xk8-xkr-17/30945d1358869959-admin-useful-diagnostic-doc-jaguarv6v8enginemanagement-pdf

https://docs.google.com/viewer?a=v&q...HCgq_ZoW3Jc1Ig

 

Cheers JagV8, Theres on codes at all, it comes back with 'no fault codes', my OBD is working fine on my other cars.

Its my mates jag and its VIN is before M45254.

Thanks Simon.

 

Evap system test is usually the last cycle to complete - here is what I did (gas level between 1/2 and 3/4 tank - car must be cold - meaning not driven within the past 6 hours - start car - plan on getting to a highway within 5 minutes of starting the car - DO NOT shut off the car once you start it - maintain a constant speed between 45 and 70 for about 20 minutes - that should do the trick - also the ambient temp must be above 40 degrees F)