Re: failed the emission test! (archive)

Hi everyone, my 97 540ia had just failed the emission test! The NO level was three times above the max emission allowed. To cure the problem, the machanic at the testing facility changed the oil and the thermastat. He said the engine was running too hot and the engine oil was really black. The question I want to ask you is that I was told by a friend of mine about BMW engines are naturally hotter than other type of engines and hotter temp. was suppose to reduce the emission. Also, if the thermastat was ajusted wrongly, would the engine be harmed. Lastly, I don't understand why the engine oil turned so black since I just had an oil service about a month ago.
thanx in advance.

You engine coolant is supposed to run about 109C.

My understanding is that BMW do not run them HOTTER than others, but rather that they try to keep them in that hot range all the time for emmisions.

If they get too hot there are some programs that will kick in to lower the temp for a while.

Regarding your oil - make sure you are running synthetic. Regualr oil will turn balck earlier because it is oxidising - heat does that to regular oil.

Before doing an emissions test you should:

- take the vehicle for a good run to clear any carbon (upper RPM's).
- change the oil.
- clean or replace the plugs.
- make sure your airfilter is not old (new is better)

And on the way to the test take the vehicl through a good run again (use some upper RPM's again) to make sure it is fully warmed up and all excess vapours burned off.

Cheers
Jim Cash

Follow Ups:

Also make sure you are using 92 octan fuel before DavidK 16:54 9/03/2000 (0)

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