Hi all
OK.. Although I have a fresh mot..
Gas was tested tested on left hand exhaust pipe with perfect figures.. So a pass...
But i was checking the running live figures and have found a difference between bank A, (left I assume)
And bank B...
I took it for a good 20 miles run. Sweet as a nut..
All running smoothly..
However watching the the live figures from icarsoft v3..
I note the lambda. Figures are very close, along with voltages.. However fueling long term is very different..
I have attached photos... At idle and at 2000 rpm
Hopefully the photos will tell you something...
No engine light, does 27 to the gallon... But something is obviously wrong..
Any thoughts please?.
Thanks in advance.

 

Provided the engine is running smoothly and there are no misfire codes, I don't think those long term trims are anything to worry about. I've always understood that trims that are within 10% either side of zero are acceptable.

Richard

 

Ah interesting!. I am aware the right bank has a Co of.0.5 and the left about 0.2...just curious... And if not to top critical.. All good. Just slightly worried!!

 

ECT isn't reading as fully hot - was it, though?

-10% on only one bank at idle is a puzzle. Usually people have +xx% for an air leak - but not here,
or -xx% on both banks for such as dirty MAF - but also not here.

Something to overfuel a bit on just one bank? (Not ECT, it's common to both of course.)

hmm, slightly blocked cat?

You could look at the causes of rich codes (which you're well away from) that would affect just one bank.

It's not really a big worry, just a puzzle. If it gets a lot worse it'll need figuring.

 

I remember reading that the accepted tolerance is +/- 10 combined, not 10 on each side. IDK what is the right number. On my car, if I got to -10, then a restricted performance notice was shortly forthcoming.

Z

 

Ah nothing like that, no codes aside from.. It always says incomplete scan what ever that means. See attached.
Also it is a new cat last year on the right bank so should be OK.
I am not sure what it means about doing more cycles?
[img alt="Each time I do this the number goes up by 1!!
"]https://cimg8.ibsrv.net/gimg/www.jaguarforums.com-vbulletin/2000x1639/img_20260430_153111_acbe57730dd64c2334ae259b70210b 6761a3d437.jpg[/img]
Each time I do this the number goes up by 1!!
Maybe I am missing something obvious. I don't mind mechanical stuff, but this is a, wee bit ethereal!!

 

Thank you 😊

 

He has one new cat and one old cat, so that is probably the answer - different airflow between the two of them?

For the OP - as your lambda readings are very close, that means the computer is doing its job properly and getting the fuel/air mixture right. It can keep on adding or subtracting fuel up to 20% before a code is triggered, so it looks like your car is well within its design limits. Not bad for a car whose factory warranty ran out 23 years ago.

By the way, that image you posted didn't work, but maybe it's the drive cycle readiness monitors - not a problem if you are in the UK as we don't use them, preferring the probe up the exhaust pipe method.

 

Ah thank you, I will try to post it again!

Just so odd that the new one is the 0.5. CO.. But maybe some good miles will clean everything out, after the winter lack of use! 🙏

 

I think without any DTCs I'd just re-check every now and then to see how the trims are. (Checking it's running CL of course.)

If it stays at -10 or nearer zero, I'd just keep driving it - it's good for cars to be used (get oil properly hot, so 20mins drive at least). Cat convs also need to be hot reasonably often so they don't gunge up.

It's a bit worrying that it's had a new cat. But hey.