re: <E28> Help, very high hydrocarbons on emissions test

["Chuck MacWilliam" <chuckmac@xxxxxxxxxxx>]

>Date: Tue, 19 Jan 1999 22:33:11 0000
>From: "Brian Franchuk" <Brian.Franchuk@domain.elided>
>Subject: <E28> Help, very high hydrocarbons on emissions test

>Hi all,

>I just took my 88 535i to the emissions test station and got some bad 
>news.  The hydrocarbons reading was excessively high (168ppm) and
>very close to failing.  I connected a scope to the oxygen sensor 
>output to check if I have a bad sensor.  I saw a signal that varied 
>from .1 to 1 volt every few seconds when the sensor was connected to 
>the DME.  It looks like the sensor is working properly.  The other 
>thing I noticed is that the exhaust has a bad odor; not like 
>sulfur but perhaps more like a lawn mower engine.  It almost seems 
>like the cat is dead.  Is there any way to check this?  Is it 
>possible that the O2 sensor is working improperly even though it's 
>generating the proper voltage signals?

>Any help is appreciated.

>Brian Franchuk
>87 325
>88 535i with bad breath

Brian, 
I just went through the same thing with my truck.  One of the most 
important things you can do to pass the hydrocarbon emission test is to 
get the engine good and hot just before they test it.  This will save 
you much hassle time!  When they tested my truck cold, hydrocarbons (HC) 
read 155ppm at 15 mph with a max allowance of 155ppm and 150ppm at 25mph 
with a max allowance of 105ppm.  After warming up the engine, 15mph HCs 
dropped to 43ppm and 25mph HCs dropped to 37ppm. It's still possible 
that your catalytic converter might be in need of replacement but 
heating up the engine usually helps a great deal.  Good luck!

Chuck MacWilliam, R.N.
'92 525i
'85 325e 
'90 Chevy Silverado
BMWCCA# 150982
http://www.geocities.com/HotSprings/Spa/9057
Sacramento Valley Chapter


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