running too lean

[reiss]

Hi my engine management lights come on on my d3 audi a8 4.2 v8 after a diagnostic its showing as running too lean could anyone enlighten me as to what needs replacing or fixing and why its showing this fault

[ADU UR quattro]

I would check fault codes to start with.what part of the world are you in, there must be some one near by with vagcom, that would be willing to plug it in for you.

[ainarssems]

First you need to determine if it is actually running lean or if ii just thinks that it is running too lean.

If it is just thinking that it is running too lean then it's faulty lambdas.

Otherwise it could vacuum leak, faulty MAF or not enough fuel due fuel pressure regulator, fuel pump, clogged fuel filter or injector.

[A8 Doc]

Do a lambda test in VAGCOM if I were you. Lambdas are a biatch to get to on these. Hopefully the MAF is at fault

[reiss]

Originally Posted by A8 Doc

Do a lambda test in VAGCOM if I were you. Lambdas are a biatch to get to on these. Hopefully the MAF is at fault

its showing as running too lean bank 1 i always use shell v power someones told me to be very careful as driving it could be damaging engine

[A8 Doc]

Originally Posted by reiss

its showing as running too lean bank 1 i always use shell v power someones told me to be very careful as driving it could be damaging engine

Yes it certainly could be.

As it says just one bank I would suspect possibly an injector or lambda.

In Vagcom you can do a lambda load test, I suggest you do this as it individually does each lambda sensor to check it.

Check your injectors as well.

[Just_Ben]

Check inlet manifold is tight! They come loose and draw unmetered air in.

Failing that, secondary air system leaking or split vacuum pipes are most likely.

[ainarssems]

Would not vacuum leak affect both banks instead just one?

[reiss]

Originally Posted by A8 Doc

Yes it certainly could be.

As it says just one bank I would suspect possibly an injector or lambda.

In Vagcom you can do a lambda load test, I suggest you do this as it individually does each lambda sensor to check it.

Check your injectors as well.

could you tell me how to do the lambda load test on the Vagcom?

[Just_Ben]

Originally Posted by ainarssems

Would not vacuum leak affect both banks instead just one?

No, the fault code designation is funny so it sometimes only logs one bank, just to confuse ya!