Hello and WHELP !

[Barfa]

Own a 1997 Z3 (California emissions) 1.9 with 205,000 miles. Engine rebuilt 5,000 ago. Just failed to pass smog test due to test issues. The actual emission numbers are fine but there is something going on that the testing equipment doesn't like....
I've tried the long drive before testing, which used to work, but alas, no more.

The only clue I can share is this; The check engine light stays off as long as the car is traveling level or up hill, butt as soon as we travel downhill braking on the engine Check Engine lights right up. {If I shift into neutral and coast down hill, no problem.)

Anybody ?
Thanks for any clues.

 

[ExMX5owner]

No clue, at all. However someone here will have the knowledge I am certain. Welcome anyway.

 

[ChrisD]

Own a 1997 Z3 (California emissions) 1.9 with 205,000 miles. Engine rebuilt 5,000 ago. Just failed to pass smog test due to test issues. The actual emission numbers are fine but there is something going on that the testing equipment doesn't like....
I've tried the long drive before testing, which used to work, but alas, no more.

The only clue I can share is this; The check engine light stays off as long as the car is traveling level or up hill, butt as soon as we travel downhill braking on the engine Check Engine lights right up. {If I shift into neutral and coast down hill, no problem.)

Anybody ?
Thanks for any clues.

Your engine controller stores codes that will indicate what the problem is. Get the codes read and you will will have better information than a bunch of random guesses.

 

[Shelly]

 

[Devon Z]

 

[Mint]

Hi and to the forum from me too in Stafford, England. Agree with @ChrisD, you need to get the codes read, that will point you in the right direction.