Good day!
Right now i got a problem with my XJR AJ27
during my HU test (security check in Germany) my car was running so lean they wont give it a pass.
Lambda was at about 1.2xx, engine was at operation temp, rest of the values where perfect, cats work properly.
No codes and the car runs very good.

Mods done 7% smaller upper pulley, first and second resonators deleted.

My thoughts to solve the problem:
- change the fuel filter and check the fuel pressure

Do you have any additional ideas because of my problem and may the value for the fuel pressure?

Best regards out of Munich!
Maxi

 

Max, running lean without codes is usually an unmetered air leak, either induction tube, throttle body gaskets or MAF - check them all.

 

That's a terrible lambda!

See threads about watching fuel trims etc.

BTW it's not running OK. You just haven't been able to tell.

 

Thanks for the advice, i will check the whole section.

JagV8 i'm sorry, i don't understand your statement
Because of what should i'm not able to tell?

 

You said it's running very good. It isn't. You haven't noticed.

 

Sorry, but i have the car now for about 9 years, just one owner before, now 103k km, the engine and transmission has just about 35k on it.
I know how the car was running at the beginning and the behavior hasnt changed over the years.

I'm very sensible for noises or uneven engine smoothness.
Another point, if it would run so bad 100-200 time is 14.6 sec on 25 C° outside temp, 80% fuel, 2 person inside, A/C off.
Messured with Vbox, no bridges, plain surface and no forest around.

Ever tested yours and got a time for me to compare?

 

You won't notice things like bad fuel trims that are burning up cats. You won't notice typical misfires that do serious damage.

Neither of those typically affect what you posted.

 

Good day everybody!

Sorry it took some time to test and do all the things based on your advice...

But after all there i no change, the car is still running lean.
So I decided to change the upstream sensors with Bosch 15627 pieces.

Do you have any idea where i could get them for a resonable price? Because here in Germany they charge over 300 € for them.

Best regards out of Munich!
Maxi

 

BOSCH 15627 Oxygen (O2) Sensor | RockAuto