Does your reader provide O2 Sensor codes? How many miles are on your car? It is an 2004 correct? What codes have you had to lead you to replace the MAF?

 

Oh, the fun with fuel trims ... I feel with you.

Just to exclude the catalysts (or at least put them to the end of the priority list), damaged catalysts wouldn't cause the observed effect. If the coating is damaged and conversion is lacking that is bad for the environment, but wouldn't concern the lambda probes in front of either catalyst. They just look for oxygen in the raw emission coming out of the engine.#

As you have similar readings on both banks it is unlikely that the problem is behind the engine (i.e. on the exhaust side) because a leak in the exhaust would only affect the reading of this one bank. The exhaust pipes only connect after the catalysts. Not impossible but extremely unlikely to have leaks in both exhaust sides that are "calibrated" in size so that they have the same effect on both banks' readings.

So you need to look at everything that both banks share.
- intake systems after MAF
- throttle module
- all hoses connecting into the intake system
- PCV systems (both part and full load)
- vacuum line to the brake master cylinder
- sealing between intake manifold and cylinder head
- oil dipstick sealing
- oil refiller cap sealing
- evap system
Probably some more when thinking and searching longer, but that's the list I go / went through on mine currently.

Oh, and when all that is to no avail, there is still the theoretical possibility that the fuel injection system is not delivering enough fuel through the injectors. Maybe fuel pressure is too low, so that the mapped injection timings are resulting in too low fuel quantities? Again, it would have to be a problem that affects both banks the same, so no individual injector but something systematic.

 

I'm not sure the PCM can actually enrich the mixture >50% combined. Do you have another scan tool you can try? My intuition is that there's a decimal point missing from those readings.

If they were 14.6, 14.8, 12.9, etc, that would make sense. When the combined LT and ST trims exceed 20% or 25% enrichment (can't recall the code setting criteria offhand) the PCM sets a lean code.

 

removed after rechecking my own trim values

 

I have read similar figures for my XJR using the carsoft i930
However when I chose another way to read the data on the scanner, I think OBD11 diagnose and 'LIve Data Stream' the figures for all the trims were well within the expected limits
I'll check tonight how I read the fuel trims that seemed normal.

 

To test for air leak(s):

with hot engine, park, look at idle and then rev to about 2500 and look again.

If they drop a lot you've a leak. If not and they're not near 0 then more diagnosing needed.

 

Hi MooSSe,

Please don't keep us guessing - tell us the year, model and engine of your Jaguar. It's best to add this info to your signature line so it shows up in all of your posts. To do so, use your User Control Panel (User CP link above left), then find Edit Signature in the left column of your Control Panel, add your car info and save your signature.

Thanks!

Don

 

if i pull the PCV pipe off whilst the car is running my icarsoft I930 sets a MIL at 20% and maxes out at 25% .
pcv pipe off/removed is a massive vacuum leak .
yours is off the scale as if your heads are removed .

i think your I930 needs a software update .
it should look like this - and even this has decimal point's -

 

 

 

Sounds like you're just about there

 

I had exactly the same, after the leak was fixed the LT didn't want to drop below 10 for several hundred kilometres.
After a hard reset and the corresponding revival procedure (described very well here in the forum) they finally started at zero again and didn't go back up. I would recommend that to you too.
There seems to be some glitch in the adaptation programming that keeps the LT stuck around 10 on their way down. And ST will then compensate with -10 ... it needs help to get over that.

 

I had lean codes for bank 1 which ended up being caused by an intake manifold leak and a valve cover leak. Check the connector piece on your valve cover (where the vacuum tube from the air intake connects). See if it is broken (mine was).