m30 mot failure help

[nickso]

my 335 just failed its mot yesterday

CO reading was 3.75....a pass of course is 3.5

ive read on here that the blue temp sensor can cause this on m20 engines but is it the same deal for an m30?

the spark plugs are black indicating running too rich

dont really want to mess with the afm unless im sure there is nothing else to check first.

should have known something was up when i got 180 miles out of a full tank


nick

[ed325i]

Have you got a clean air filter?
The CO is not that far out I would just ask them to adjust the air flow meter to see if it comes down 1st.

[Brianmoooore]

Blue temp sensor would have exactly the same effect on an M30 as on a M20, I should think. If the plugs are black, it's worth a try.
Do you get slightly hesitant acceleration?

[nickso]

Have you got a clean air filter?
The CO is not that far out I would just ask them to adjust the air flow meter to see if it comes down 1st.

air filter is a brand new k+n panel filter....wont make any difference will it?

[nickso]

Blue temp sensor would have exactly the same effect on an M30 as on a M20, I should think. If the plugs are black, it's worth a try.
Do you get slightly hesitant acceleration?

not really noticed anything while its hot but it runs poorly when its cold and is very often a poor starter.

i read in haynes that the CO reading should be some impossibly low number like 1.2

only problem is its going to be difficult to test the CO at home

[ed325i]

it runs poorly when its cold and is very often a poor starter.

I had this on my 325 I had the injectors cleaned and it was ok.