Hello everyone,

I took my vehicle in for the always-fun smog test. As you can tell from the
title my 1992 MR2 failed the smog test. I have a naturally aspirated 5S-FE engine. This is the first time that my car failed the smog test. Here are the results in the hope that someone can shed more light on the situation or at least point me in the right direction of how to repair the problem
Test 1 @ 15 mph
RPM @ 1879
%CO2 = 15.6
%O2= 0.0

HC (PPM)
MAX=121
AVE=31
MEASURED=119

CO%
MAX=0.76
AVE=0.10
MEASURED=0.36

NO(PPM)
MAX=807
AVE=237
MEASURED=189

TEST 2 @ 25 MPH
RPM@2095
%CO2= 14.4
%O2= 0.0

HC (PPM)
MAX=96
AVE=20
MEASURED=157

CO%
MAX= 0.65
AVE= 0.09
MEASURED=1.80

NO (PPM)
MAX= 747
AVE=199
MEASURED=58

As you can tell, my MR2 failed the HC test @ 25mph and the CO (%) test also at 25mph. Any tips or suggestions would greatly be appreciated.

Thanks

how old are the plugs + o2 sensor?

ac427cpe,

As far as I know the plugs and the O2 sensor are the originals that came with the car. I have most of my vehicle's maintenance records and it seems that the O2 sensors have never been changed. Is that something you would recommend?

Thanks.

yeah, I've had them go bad on 3 mr2's :\ (hopefully they aren't the origonal spark plugs!)

Folks have passed smog tests after using auto-rx.
www.auto-rx.com

I say that the o2 may be a bit old and getting "slower" not keeping up with the ever changing exhaust charge or it may be coated preventing a accurate reading. It looks like both the 15 and 25MPh tests are not looking very happy...I'd change both the plugs and O2 to start ( they are both relatively cheap). GL