I have a 1994 Impreza 1.8

Trying to get it smogged (in CA)

It failed the "Idle Emissions"

at 739 rpm hc measured 430 co measured 2.51

 

Everything was great at 2390 rpm. hc: 11 co: 0

 

I'm trying to find out the most likely cause.

 

Thanks.

How about a good old fashioned tuneup to start off with?

 

 

nipper

How about a good old fashioned tuneup to start off with?

 

 

nipper

 

Ahhh Nipper.

 

Always ready to pull out a traditional type of wisdom.

He's right. I'll bet you're HC and CO are high from poor combustion at idle. Weak spark and old plugs.

 

I'd try:

 

New spark plugs and wires.

 

New Fuel Filter.

 

New PCV valve.

 

New air filter.

 

Change oil.

 

 

 

 

Then I would go for a long hot drive on the freeway before testing. The hotter the Catalytic, the more efficient it is(to a point, I know, I know).

 

But definately get her good and warm, and run some good fuel.

I have also heard that if you have to wait in line for emissions testing, keep your car idling, don't turn off the motor. You want to keep the motor at normal operating temperature for best emissions rating.

What are the limits at idle? In other words, how bad did it fail? Awful? Barely?

What are the limits at idle? In other words, how bad did it fail? Awful? Barely?

 

hc max is 100 I hit 430 Co max is 1.0 I hit 2.51

you are really rich. you need to find out why. check the o2 operation and also check for vac leaks as this will drive the o2 to richen up. once you find what the problem is you should be ok. if yer hc is still kinda borderline even after the c.o. is ok then you got a bad cat converter. probably ruined due to the rich running. sometimes you can rehab a converter if its not physically ruined by going down the road in sec gear at about 3,500 to 4,000 rpms for a few minutes. as mentioned already a tune really needs to be done first if not done recently.

 

george

 

 

 

 

 

hc max is 100 I hit 430 Co max is 1.0 I hit 2.51

I'm with nipper tune up. I time my tuneups with emissions time my cars get there with about 100 miles on a fresh tune up. Haven't had a failure yet. I'm not in CA but RI emission testing is probably close they've change twice recently to tight standards.