'97 3.2, 150k miles 5'CPS Bracket, k&n pod filter. Failed the UK MOT on ABS light (which I knew about) but also emissions (which wasn't expected, last year was well within tolerances, the only changes since then have been an Andy Bracket and K&N filter, along with new spark plugs)

fast idle :

CO 2.45 (0.30 max) fail
HC 120 (200 max) pass
Lambda 0.91 (0.97-1.03) fail

2nd fast idle test :

CO 1.94 fail
HC 42 pass
Lambda 0.93 fail

Do these figures give anyone a clue as to where I should be looking ?
Will refitting the standard Crank Sensor Bracket, and standard airbox help ?

Any help gratefully received

 

You almost certainly have a CEL, right? What OBD codes do you have?

Your engine is running rich, giving bad gas mileage and potentially burning up the catalytic converters. I have to believe you should have a code.

 

Not sure if all '97 vehicles had OBDII.

In any case, get rid of the silly K&N set up. It does nothing positive for performance.

 

All X-300s have OBD ECUs!

 

Try checking your lambda sensors. I failed an MoT for emissions without any warning lights or codes, or any perceptible difference driving the car. Friendly Jag technician took one look at the readings, and diagnosed the fault. "typical" he said, but I'm afraid I dont remember what the readings were. Hope this helps.

 

Hi,when I first got my x300 it too failed its MOT on high emissions, the MOT tester said probably o2 sensors, living close to a independent jag specialist I let them check it out and it turned out to be a faulty maf sensor which they replaced and retested the emissions and all was OK again, I also had no codes showing and no CEL,.

 

Not surprising, the oil from the K&N filters has a tendency to deposit on the MAF sensors and kills them.

 

Hi, yes I have heard of this happening, but I'm on stock air filter.

 

Thanks everyone for the replies - sort of confirms my suspicions. I have replaced the standard airbox, which will now stay there, and as a precaution the Andy bracket too (albeit temporary, I'll be putting that back on after it passes) as it passed easily last year in the standard configuration. That and cleaning the MAF sensor, should establish whether it's the Lambda sensors.

The engine warning light is off, and no codes - although the smell of petrol sometimes at tickover does suggest rich running.

Dropping it off today - I'll let you know the outcome (my money's on Lambda sensors - literally lol)

 

Lambda/O2 sensor at fault - replaced and emissions back to well within tolerances. MOT passed, and all is now well with the world.

The original airbox is now staying on just in case

 

Great. It is always a pleasure to hear a good final outcome and give the rest of us good indicators of possible solutions!

 

I have Andy brackets on 2 of my 3 cars and they have never caused emissions problems.

 

My fuel consumption improved ( slightly) after fitting my Andy bracket, from which I would conclude that it reduces emissions, again, slightly.