94 Legacy failed emissions - now what?

[Zootal]

1994 Subary Legacy. Non-turbo. 4dr at sedan. 240,000 or so miles (might be 280,000). Burns a bit of oil, but maybe one quart between oil changes at the most.

 

Today it failed emissions, hydrocarbon too high. It has new plugs, new air filter, new fuel filter. Plug wires look perfect, coil is clean. Runs perfectly, no misfire that I'm aware of. Check engine light does not come on. Fuel mileage is the same as always. I haven't checked compression, but it turns over evenly fwiw.

 

What else is there that can go wrong to cause this? I hate to start throwing parts at it, but I'm thinking  O2 sensor next, and then what? Any kind soul here have any experience with these older cars and emissions and know the things most likely to cause this?

[Zootal]

Oh I forgot to ask - at this high mileage, should I be thinking of fuel injectors? Do these need replacing after a while?

[wtdash]

Hi 

this LINK may be useful.

 

 I'd start w/the O2 sensor. I'd also clean the MAF sensor. ...use the MAF specific cleaner as I've read Brake Cleaner is too strong and the spray velocity can damage it. BTW, your MAF is the same as every other 2.2 (except turbo models) and 2.5 from '92-'98 (and '90-'91 Automatics).

 

Injectors certainly may be getting old, but w/it running OK 'as is' I'm not sure. You can do a quick resistance test to verify they're around 11-12 ohms.

Edited March 13, 2018 by wtdash

[sparkyboy]

My 92 legacy failed the emissions test because of a faulty knock sensor. (I believe I had high HCs and failed one of the other parameters as well) There was no check engine light and she drove fine most of the time,  but I could get her to act up when driving a certain way. I changed that sensor only and tried again, because I was on day 7/7 for my free retest otherwise I would have done more. But she passed the retest. The fsm for the ea82t says you can test the knock sensor by hooking a multi meter to it and hitting the engine block with a hammer, ha!

Luckily the ej one you can just take off and look :-)

No vacuum leaks? She runs at proper temp, yeah?

High HCs means not having a good burn or running rich? i would suggest timing, but you know...

Edited March 14, 2018 by sparkyboy

[Zootal]

Bad knock sensor? Weird...it must have kept retarding the timing, thinking it was knocking. That would definitely effect performance, because the ECU will retard the timing if it thinks it's knocking. But you would not think that would cause emission failure, but who knows? They are dirt cheap, maybe I'll slap one in for S&G.

 

No vacuum leans that I am aware of, it idles as smooth as can be. Engine temp is good, it has an authentic Subaru thermostat. Can you even adjust timing on these things? It doesn't have a distributor. Fuel economy is good, power is great. It runs great, nothing has changed - except high HC.

 

Could the catalytic converter be failing because of the high mileage?

[GeneralDisorder]

Probably needs O2 sensor, knock sensor, and a cat.

 

If that doesn't clean it up, go for about 25% denatured alcohol.

 

GD

[sparkyboy]

 

Can you even adjust timing on these things? It doesn't have a distributor.

Once my 77 chevy g10 was only running on five cylinders due to a burnt valve. (250 ci inline six) When she failed the e test i retarded the timing so much she was barely running, and she barely passed :-) maybe i advanced it, it was so long ago and i was really just doing what my dad was instructing me to do.

Edited March 14, 2018 by sparkyboy

[idosubaru]

Is there anyway the OP can monitor before/after changes to see if he’ll pass HCs before he goes? Stinks guessing and then not knowing if it’s resolved.

 

Do these early gens have P0420?

Air fuel ratio, vacuum...?

 

Can you even adjust timing on these things?

No, EJs aren’t intended to be adjusted. ECU does it.

 

knock sensors are by far the most common sensor failure on that engine. usually give a check engine light and symptoms. When I sell or give a Subaru away I install a new one since they’re inexpensive and the most common failure.

 

I’ve installed many of the $8 eBay ones without issue.

 

Front oxygen sensor is the only one that impacts engine performance for that year EJ. If you’re going to drive it any more miles it’s probabiy not a bad investment anyway. I often preventatively replace them around 180k, just picked one up yesterday for my 225k DD subaru.

 

quote name="Zootal" post="1379927" timestamp="1520987221"]

Could the catalytic converter be failing because of the high mileage?

Yes. They often can last longer but it’s a part and it’s old.

[1 Lucky Texan]

make certain the car is fully warmed-up before the test. Keep it idling if you're in a line w'ever.

 

PCV valve might be stuck open I suppose....

[kamesama980]

Burning oil can lead to high HC, that's what oil is. Burning oil will also poison the cat and o2 sensor. the HC reading could be from oil being leaked at the time of the test or built up in the exhaust.

 

Couple tricks I've heard over the years:

1. pull a plug wire (and ground it so you don't get zapped or burn it up) so you have one cylinder dumping fuel into the exhaust. raise the RPM a tad (1-1.5k) to keep it running. The extra fuel will combust in the cat building up lots of heat. The extra heat may burn off some of the carbon buildup and return enough cat functionality to pass. Of course "enough" happens to be right next to "melted catalyst" and "get the fire extinguisher".

2. is slightly less interesting because it's just hop on the freeway for 10 minutes before you go get it checked without using overdrive (again to build up heat but in a more limited fashion)

3. run the tank near empty put a few gals of e85 in (just enough to run o bit, take the test, and get to the gas station. take test. fill with "normal" gas.

4. move out of whatever liberal, overpopulated, soul-killing craphole you live in.

 

No guarantees with any of them and a few risks that I mentioned.

 

OBD1 has only basic codes. That's one of the major advertised features of OBD2: more/better codes and somewhat more ability to know if it'll pass.

[Zootal]

Tyvm everyone. Knock sensor - huh never would have thought. Got one on order. O2 sensor - also cheap - I'll just replace it while I'm at  it.

 

Any suggestions as to where I can find a cat that actually fits? All I've been able to find are after-market generics that need to be welded in place.

 

AND just to make things interesting - "Honey, did leave the engine running while in line, right?" "No, I shut it off so it wouldn't get hot". At which point I start banging my head on my desk but sadly all that did was give me a headache....<sigh>....

 

So yeah, I'm replacing knock sensor and O2 sensor this weekend, and this time I'll make sure the engine is HOT and see if it will pass. If it doesn't, I'll go for a new cat.

[Zootal]

4x4 labs has a direct fit front cat and pipe assembly, $300. Looks like that will be my next stop if it doesn't pass.

[Bushwick]

Engine just needs to be fully warmed up prior to testing. Shutting it off in line, then restarting after a couple minutes won't hurt anything, unless you have a code ready to set during next restart. Main thing is that the cats are at full operating temps prior to testing.

 

Kinda surprised GD recommended alcohol, as that can actually make things worse (that would fail an Ohio e-check).

 

Run whatever gas the engine normally uses in it. If it were me and the car was barely failing, I'd reset the battery, run the car a good 25-30 miles on the highway or leave it in "3" and cruise at 45mph on some long back road for that length, then take it in for the test (after the knock sensor). Maybe stomp on it a few times to blow all the crud out.

 

If your tailpipe is really sooty, then it's running rich. If it's running lean, you might have a vacuum leak, intake leak, etc. Would be wise to do the O2 sensor at that kind of mileage. If thinking injectors, there are ways to test them to see if they are spraying correctly or not, though it might be cheaper/easier to get lower mileage used.

 

w/o codes or proper testing equipment, it's going to be a crap shoot to sort.

[GeneralDisorder]

I have personally used denatured alcohol multiple times here in Oregon. It is very effective at reducing hydrocarbons. I dont know about Ohio but it works here.

 

GD

[Gloyale]

NGK standard or v-power plugs (no iridiums, no bosch)?

[1 Lucky Texan]

a product called RXP seems to have a good reputation around here for helping pass emissions - never used it myself.

 

 

might be alcohol hah!

[Bushwick]

Our programs are still state-level IIRC. They used to be really strict (late 90's, early 00's) and now seem to care more about a CEL being OFF at idle with OBDII scanner connection = fast pass with simultaneous 10 sec tailpipe sniffer idle-speed detection vs. older testing of leaving a tail pipe sniffer in for 5-10 minutes as they did a real-time run on dyno rollers driving through the gears and watching a screen with real-time speed curves where the operator had to match the car's speed with a curve graph to simulate actual driving. They measured HC, NoX, CO, and something else I'm forgetting. Adding alcohol to a normally running car would have failed it in the older test. Also, might wanna be careful as openly admitting to cheating emissions testing as it is still a felony. Had a friend in HS that still has a felony because of something stupid he did 20 years ago.

[GeneralDisorder]

Ours are also run by the state. They ripped out the dyno's years ago. The OBD-II lanes are now self service. The sniffer is idle, and 2500 rpm test. I've passed it multiple times with alcohol from the paint store.

 

The powers that be can't prove a thing in a court based on internet forum chat. Besides none of them are even in my name. I register all mine outside the test boundaries.

 

At the end of the day they don't care either. Its just a money grab and anyone that cares to can easily circumvent the test. If not by directly cheating you can simply register the car to an address pulled from google maps that's outside the test boundaries.... which is the VAST majority of land in OR.

 

GD

Edited March 18, 2018 by GeneralDisorder

[Zootal]

Here in Phoenix, AZ, they still run them on the dyno for about 30 seconds.

 

So I replaced O2 sensor, detonation sensor, plugs ( plugs were clean, did not need replacing), air filter. Took car out and got it good and hot. Test. Pass. *barely*. HC at idle was 216, limit is 220. I looked up previous tests, and the HC at idle two years ago was about 20 or 30, very low. I think this cat is on it's last legs, as nothing else seems to be wrong. Plugs were clean, tailpipe is clean, idles as smooth as can be, runs great, gets great mileage.

 

If we can get another two years out of it, I'll replace the cat next time around, but I don't expect it to last another two years. The transmission shifts hard and it's burning about a quart of oil every 1000 miles. My wife is a lead foot stop/go driver, and the tranny clunks every time she steps on the gas or lets off. Didn't used to do this. I've felt it slip a time or two, and I'm just waiting for it to finally die.