Failed emissions test-- any suggestions?

[davew833]

My '94 LS failed its annual Utah emissions test today. HC and CO were over maximum allowable limits at idle-- they were OK at 2500 rpm. No check engine light or any other obvious signs of trouble were noted. Any suggestions on where to start troubleshooting? The tech suggested a "tune up" but I'm not sure what that even involves beyond changing the spark plugs and air filter (which is new.)

It also has an ECUtune chip which is set for allowing regular unleaded right now-- would this cause it to fail?

[icingdeath88]

Originally Posted by davew833

My '94 LS failed its annual Utah emissions test today. HC and CO were over maximum allowable limits at idle-- they were OK at 2500 rpm. No check engine light or any other obvious signs of trouble were noted. Any suggestions on where to start troubleshooting? The tech suggested a "tune up" but I'm not sure what that even involves beyond changing the spark plugs and air filter (which is new.)

It also has an ECUtune chip which is set for allowing regular unleaded right now-- would this cause it to fail?

Yea it might. The way the chip allows you to run regular gas (AFAIK) is by letting the engine run a bit richer (more fuel) than normal. That could cause a small increase in emissions.

If everything else is in good shape, then I'd start by flipping the ECU switch back to premium, and the gas in the tank back to premium as well. Then drive the car around for a tank or two before going back to be re-tested.

[1986nate]

Originally Posted by icingdeath88

Yea it might. The way the chip allows you to run regular gas (AFAIK) is by letting the engine run a bit richer (more fuel) than normal. That could cause a small increase in emissions.

If everything else is in good shape, then I'd start by flipping the ECU switch back to premium, and the gas in the tank back to premium as well. Then drive the car around for a tank or two before going back to be re-tested.

I have to agree with Icing. Go back to premium for a couple tanks of gas. Make sure to drive the p!ss out of it to some extent and go in for a retest. Then report back if you fail or even if you do pass for others who might be in the same situation.

[DaveSVX]

I don't know if your emissions testing is anything like ours in Vancouver but my SVX I sold last year failed a few years ago.

I took it directly to the Subaru dealer where I usually had it serviced and the guy there told me to drive it for 20 minutes on the highway and rev the engine to keep the exhaust system hot just before driving into the test.

I went back to the testing centre an hour later and it passed with flying colours. I never had a problem with emissions from then on in my older SVX or with the '97 I have now.

[Tapani]

The inspection guy kept the revs up at around 2500 for at least 2-3 minutes to get the (aftermarket) metal race cat to operating temp..... all was good after that.... before that the HC and CO were very high, after the heat up cycle they were way down low, next to nothing. He knew what he was doing.

The inspection guys over here are all automotive engineers.

Tapani

[davew833]

Well, it passed easily the second time around. I did a bunch of stuff- not sure what it was that did it, but we'll start with the obvious things:

-The ECUTune switch was actually set to 'Premium', but my nephew who's been borrowing the car has been putting regular in it-- therefore, I ran all the regular out of it and did a couple of fill-ups of premium, including adding fresh fuel right before the test.

-I added a bottle of fuel system/injector cleaner to the fuel.

-I did some high-speed/high-power running on the 75 mph desert freeway near my home, including right before the retest. I came in to the testing station with the car running, the cat hot, and didn't shut it down. Fortunately, I didn't have to wait to get back in for the retest.

-I changed the oil since it was due for a change anyway and I know dirty oil can affect emissions.

-I checked the visible vacuum lines, air filter, ignition coils, pulled a couple of the easy-to-reach spark plugs which all looked OK.

-I adjusted the TPS.

-I cleaned the accumulated oil off the O2 sensors. (Someday I WILL find the source of the remaining oil leaks under my car-- I've fixed all the obvious ones.)

Then I muttered some threats under my breath about selling the car to the junkyard or driving it off a cliff if it didn't pass and I sacrificed a pristine one-owner 1988 Hyundai Scoupe to the car Gods (I think Ray and Tom are their names...)

So, I'm not sure what did it, but I'm glad I didn't have to go to the effort and expense of replacing the O2 sensors, or the Cat, or all the spark plugs, or (insert the name of some really expensive and labor- intensive part here).

[1986nate]

I'd be willing to bet having the proper fuel fixed the issue. Glad to hear it got sorted out and you passed!

[icingdeath88]

Cool, congrats on passing, and thanks for updating the thread with the outcome.

[davew833]

I suspected the fuel/ECUtune switch was the cause, but in Utah you get one free re-test and then it's another $35 so I wanted to ensure the maximum possibility for passing before I used my freebie...

[VICSVX]

glad you got yours to pass....

now i need some advice on how to make mine pass lol

i did a drivetrain swap (everything) from a 92 Ls with around 160k miles on it and into my 94 L. the 92 passed last year as the tags expired JUL12. after the transplant my 94 will not pass

it is stock other then the muffler and intake. there was premium gas sitting for a few years about 1/4 tank and i topped it off around 1/2 tank with regular just to move it around. i did turn the car off as i was sitting in line (about 30min). there is fresh oil in it and no CEL.

i will run her dry and fill up with premium and add some injector cleaner a few tanks before i retest. other than that idk what else to check and try

help plz

thanks

ps: i am so happy to have drivable again tho...i missed driving her

[bishop]

run some seafoam through the brake booster or iacv line.

[VICSVX]

does seafoam really work...?