Emissions question

[SignusPrime]

New to the forum, just acquired my first Subaru about a month ago, and had been lurking here since then in hopes of finding some info, but had a more specific needs than the threads I've seen.

I have a 1993 Legacy wagon, 220k on the odometer, and it refuses to pass emissions. It has new plugs and wires, a recent oil change, and isn't throwing any codes. The only problem I'm having is with the idle HC numbers, even after doing 30 minutes of highway driving beforehand to get to a testing station without any waiting, so I'm sure it was up to temp. I'm just out of ideas, and feel like I'm beating my head against the wall. Any help would be appreciated!

[rallyak]

I would change the violent sensor, that won't throw a code and it is one of the major sensors that directly effects air/fuel mixture and its cheep 20$-25$.

Stupid autocorrect: coolant sensor

[SignusPrime]

Thanks, I'll give that a shot, and see how it goes!

None of the shops near me have them in stock, so I get to wait.

[Legacy777]

Welcome to the BBS!

Yeah, I'd try the coolant temp sensor and see if that changes anything.

How badly are you failing on HC's? Do you have any of the other emissions numbers and their limits you can share?

[Alphius]

Run it down to an eighth of a tank and dump a couple bottles of 99% isopropyl alcohol in. Get it as hot as you can and go get tested.

[cj91legss]

I would change the violent sensor, that won't throw a code and it is one of the major sensors that directly effects air/fuel mixture and its cheep 20$-25$.

Stupid autocorrect: coolant sensor

I don't see a problem with it being called the violent sensor....

[SignusPrime]

Sorry for not replying sooner guys, been pretty busy with school lately. Changed the coolant sensor, and it helped some, but not a whole lot. All my numbers are good aside from HC's, which are still high.

1st idle reading: 247 (down from 292), Final reading: 284 (down from 321) / Idle Standard: 220
Precondition reading: 58 (down from 69) / Precondition standard: 100

Going to have my neighbor look at it later this week (he used to run an auto shop until a few years back) and see what he says,. I guess I'll run the alcohol so it'll at least pass, then actually fix whatever the problem is later on when I have more free time (or money if it has anything to do with the cats).

[Legacy777]

Yeah...that's what I'd do....get it to pass and then you can try and fix the issue as time permits.

[volny]

Is a bad coolant temperature sensor really obvious to diagnose? just curious...

[Legacy777]

No, sometimes the issues can be subtle and not so easy to diagnose.