Bit of background in case related-

PCV valve and pipework replaced last summer. Just checked around for air leaks, can't see any unless the inlet manifold gasket is gone?

Fuel pump died 200 miles ago, fitted new X5 pump as per wiki. New battery at same time.

MIL light is being thrown up roughly every 25 - 40 miles. Lambda control adaption fault. First on one bank so I figured O2 sensor. Cleared it to see what would happen. Came back on both cylinders, at this point I assumed air leak as more likely than multiple simultaneous sensor failures. On idle if I hold the throttle gently around 1000rpm it will hunt.

Using iid tool and torque the O2 sensors spike from 1 to 8 V. Lambda control both banks is around 0.985. tried to read AFR on torque but wouldn't do it, when I checked on iid tool is not entering closed loop. I do have a low temp Stat but that's been in for 3000 miles, tried it on a run its getting to 89 degrees so assume hot enough to enter closed loop?

Bit stumped now, I'm no expert using the data from either device so all advice or ideas welcome.

Thanks  2003 4.4 Adriatic Blue FF

I should also say it would appear on the surface to be running absolutely fine. 2003 4.4 Adriatic Blue FF

The o2 upstream sensors should be reading between 0v and .8 cycling every second or so on idle when warm. Rears should stay a steady .45 v. A MAF reading would help. Look for approx 22kgs hr on idle with loads off No7 - 2003 V8 Vogue

Thanks.

Lights just come back on. My torque app shows from cold it going from 'open cold ' to ' closed on O2 ' , however my iid says it's not on closed loop so that's thrown me a bit.

Before the light came back on iid said I was getting around 25 to 26 mgh from maf at tick over, no load, warm at 84°. Torque says 7 so that's a bit odd too..

And these fuel trims-

Bank 1 Stft -10.16 Ltft 5.47
Bank 2 Stft -9.38 Ltft 4.69

Screenshots attached show when lights come on, codes say running rich.
Both banks showing adaption faults code on iid.

Click image to enlarge

Click image to enlarge

Click image to enlarge

Click image to enlarge

I have similar issues but have done the PVC valve and hoses yet. Interested to see how this turns out.

Here you go. I had a dig around and found these known good MAF values from when I was diagnosing a miss fire..

idle 600rpm 17.1kg/h
1500 36.9
2000 50.2
3000 72.0

If yours is reading any different, you've found your problem No7 - 2003 V8 Vogue

I'm getting roughly from yesterday's check

Tick over / 600 - 26.2

1000rpm - 33.8

1500 - 45.8

2000 - 57 2003 4.4 Adriatic Blue FF

I'm getting the very same fault - we live in Farnborough, it must be the air!

MAF is on the list to change - there's 30% off if you order online at Euro Carparts atm...

Dont buy cheap. No7 - 2003 V8 Vogue

73+ vat off my mate at CAF

I've just cleaned it right up, now getting 18 mgh!

Also found a tiny split in a vacuum line in inlet. Also cleaned throttle body.

Going out in it now so fingers crossed.. 2003 4.4 Adriatic Blue FF

Let me know how you get on, or it is definitely the air....

I bought the Bosch MAF from Eurocarparts as if I applied a light throttle up to around 1000-1200 rpm the engine would hunt up and down considerably and with the new MAF it is great.
I think I paid £80 ish

Thanks for that. That's Exactly what mines doing at the moment..

Eml is off still. I thought it made a difference cleaning Maf but with hindsight the slight change in numbers I got was more likely from the throttle butterfly closing tighter and the vacuum line now being 100%.

Maf coming today

Ohuntsman, took the car to Fleet last night - numbers didn't move so I'm discounting the local air  2003 4.4 Adriatic Blue FF

I cleaned my MAF last year and it made some difference, the MAF may not be the complete cure but you need to know it is working 100% to be able to diagnose any other issues

New Maf giving essentially the same readings as my old one. Still hunts when you try and hold low revs around 1000rpm.

Approx 24 mgh on tick over / 600 rpm

Others same as above pretty much.

I'm going to give it a run and just see if light comes back on for now. Sure it will... 2003 4.4 Adriatic Blue FF