failed emissions test

[glogirl]

We have a 1990 Subaru Legacy, AT, AWD, wagon and it seems to run
smooth, no smoke from the exaust. Just replaced the radiator. Took it
in for emissions and it failed. Anyone with ideas??? Thank-you.

 

[Edward Hayes]

I assume the car has had a tune-up within the last 15,000 miles or so
and you have no CEL showing. I would get a bottle of "Techron Fuel
System Cleaner" (sized for 20 gallon tank) and put it in your gas.
Drive the car on the expressway for 20 miles or more at 65+ mph and
use some full throttle at times. Then drive the tank down in your
normal day to day pattern. This will clean up the injectors and carbon
that can accumulate on the back of the intake valves. Let us know how
you check out next time. Be sure and use the "SYSTEM CLEANER AND NOT
THE INJECTOR CLEANER. I buy mine at Wal-Mart for about $9 for the 20
gallon size.

 

[Backfire Burrito=Skidmark]

We have a 1990 Subaru Legacy, AT, AWD, wagon and it seems to run
smooth, no smoke from the exaust. Just replaced the radiator. Took it
in for emissions and it failed. Anyone with ideas??? Thank-you.

Start under the hood......
Your car is 16 years old. it could be (and not limited to these items)

O2 sensors
Valve guides
MAF sensor
worn rings
Dead cat convertor
Exhaust leak

Anytime you have unburned hydrocarbons going out the pipe (oil consumption)
or unburned fuel or excessive O2 the inspection
machine will lay an egg.
Time to take it to a mechanic that has his own analyzer. it might run just
fine and fail, especially in the state of Californication.

 

[Rick Courtright]

We have a 1990 Subaru Legacy, AT, AWD, wagon and it seems to run
smooth, no smoke from the exaust.

Hi,

I didn't catch where you are, nor what part of the test the car failed.

Here in California, we have a "visual" and and "operating" section of
the test. Visually, all the "stuff" has to be there and hooked up. The
timing is checked manually by the technician, then the "computer" takes
over most of the rest of the tests. Generally the car goes on a dyno
(except AWD or full-time 4WD cars--anything that could "drive itself
off" the dyno!) where there's a low speed and high speed test (actually
15 and 25 mph--not REALLY high speed.)

According to my regular smog guy (old timer), a very common source of
failure on the dyno is having "cold" equipment. He always runs the
engine at about 2000 rpm for 2 full minutes before hooking anything up.
I've never had one fail w/ him testing, even the last test on my '90
Loyale before it blew up (it was going thru a quart of oil in 250 miles
at the end) went fine. OTOH, he was on vacation last time I had to have
my Toyota truck smogged, and the "kid" running the tests was running
behind schedule, so it had cooled off waiting for him. He did NOT warm
it up before he started the test, and it BARELY made it thru, though you
could see on the results sheet just about where it started to warm up,
cuz the "bad" numbers started dropping quite rapidly! (Moral of the
story: old age and treachery overcomes youth and skill?)

He also said a lot of cars he tests are high on the HC (hydrocarbon)
section, because of wear, etc., and a new cat can cover a multitude of
sins if that's a problem area. (Mine had a whole new exhaust system
installed shortly before the engine got "sick" so the cat was good.) An
O2 sensor's a common cause of high HC emissions, too.

Finally, certain cars require a manual test of the gas cap, including
mine. He says he sends a lot of owners to the parts store for a new cap
when the rest of the systems are 100%.

So... we need more info on your car!

Rick