Zachary

I have an '05 545i with 3,600 miles on it. When I start the car, it sounds like the engine is knocking or pinging.

I have heard some of you metion this in the past. Is this normal? I DO use 93 octane fuel.

Zachary

andy545

If you mean you can hear the valves, I have this as well. It is noticeble
when the engine is cold and it is quiet inside. Usually between 1000rpm and 2000rpm under medium load. It subsides when engine gets warm.
My chief mechanic assured me that this is typical from Valvetronic engines.

EBMCS03

I havent noticed it on mine... I'll try to pay more attention to it. How loud is the "knocking / pinging sound"?

Zachary

It's not really loud - it's like Andy said, it's noticeable. And noticeable enough that my friend who has a 645 Convertible clearly heard it while he was walking to the car.

I too have noticed that it seems to go away as the engine warms up.

I don't see what the "good" is to having it knock/ping.

Zachary

EBMCS03

Does it knock like just once or twice and easily missed or is it a consistent knock for a few mintues till the car warms up?

drjochen

Mine kind of sounds like a Diesel when the engine is cold.
It also doesn' run clean below ~ 2500 rpm when its cold outside.
My dealer says its perfectly normal (but then, he says that to everything...)

Merv the Derv

93 octane sounds really low. In the UK the minimum rating is 95 but then again we are paying about $8 a gallon. I'm sure when I was in the states there were 3 grades of unleaded fuel, can't you use a higher grade? Shame you guys don't get diesel. Hang on didn't Cadilac make a diesel in the 70's, where could you get diesel from, or is it available for trucks now. Sorry this has nothing to do with your engine noise - I'm sure your in safe hands I hear BMW are still changing engines on the old E39's from 98 for free.

drjochen

93 octane sounds really low. In the UK the minimum rating is 95 but then again we are paying about $8 a gallon. I'm sure when I was in the states there were 3 grades of unleaded fuel, can't you use a higher grade? Shame you guys don't get diesel. Hang on didn't Cadilac make a diesel in the 70's, where could you get diesel from, or is it available for trucks now. Sorry this has nothing to do with your engine noise - I'm sure your in safe hands I hear BMW are still changing engines on the old E39's from 98 for free.
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93 is really low, I know. But all we have here in DE, for example, is 87, 89, and 92.

EBMCS03

There are three Octane rating systems, RON, MON, and AKI which is (RON+MON)/2 with MON < AKI < RON.
Here in the US we use AKI and in Europe Mostly RON I think. Any country use MON?

For example, BMW recommends for it's K1100 motorcycle: a minimum of 89 AKI, 95 RON.

Here in California we have 87 89 and 91 HIGHEST!!! which sucks. so 93 would be a dream for me in CA. WE do have racing fuel somewhere at 100 octane at $5 a gallon.

Iceman

Merv, the US is different. Their 93/94 is our 100.

And I have to disagree, it's a shame that ppl in Europe use so mayn Diesel engines, since they are the worst on the planet... for the environment.