my corolla is a 1998 so it did not come with a egr valve smog fail shows NO reading at 15 mph measures 1646 max is 477 at 25mph measures 1556 max is 746 and HC reading at 15 mph is 91 max is 64 at 25mph is 81 max is 47 after doing some research I replaced the mass air flow sensor it also says to replace my EVAP canister this is a 285.00 part would I be better served by having the fuel injectors serviced instead of buying the canister
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1998 Toyota Corolla Question: Failed Smog
Answer #1dandd November 26, 2010, 21:05Master
I do Emissions Diagnosis and N Calif at a Gold Shield Station.
Don't replace your Canister unless you have a Evaporative system code.
As for high NOx on this 1.8 liter engine, it uses fuel control and the Cat to keep NOx under control.
Apply for the Cap program, your car is a high emitter, you should have no problems getting assistance, which will be up to $500 with a 4100 deductible, so that is $600 total. Go to the BAR or a Gold Shield Smog Station and get the info.
As far as Diagnosis goes:
1) First make sure that your car is not over heating.
2) Replace the front Oxygen Sensor, if it has over 90k-get a Denso Oxygen Sensor, it is OEM and goes for about $162.
( the oxygen sensor starts to get slow and it does not control the air fuel ratio cleanly, the car will run a little lean at times which produces NOX, big time ! )
3) Replace the Catalytic Converter with a CARB certified Converter
which will cost about $400. ( an OBD-II Cat on this car controls about 70-80% of the NOx )
Don't just do the Cat because the slow Oxygen Sensor will wear out the new Cat in no time )
I was just involved with one of these cars this week, this is a common pattern.