Emissions trouble (high CO)

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OTTERMATIC
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Emissions trouble (high CO)

Post by OTTERMATIC »

I'm wondering where to go next in chasing down this exhaust demon. I'm failing emissions on Carbon Monoxide, just slightly over the limit. The O2 sensor, Camshaft sensor, sparkplugs and wires, and oil have all been changed. The air filter is pretty new, but I'm going to try cleaning it. There was a code for the MAF but I cleaned it and the throttle body, code hasn't returned. I also threw some "Guaranteed to Pass" fuel injector cleaner junk into the tank.

That was the last thing I've done and I haven't retested yet, want to try and make sure it's solved this time before I go back in for testing. Any ideas?

Legacy777
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Re: Emissions trouble (high CO)

Post by Legacy777 »

What are the other emissions values HC and CO2, etc.?

How does the engine run? Have you done the "d-check" mode mentioned on my site that puts the ECU into a more active diagnostic mode?

https://www.surrealmirage.com/subaru/engine.html

You may want to try that and see if any other codes come up.

Typically higher levels of CO is a sign of incomplete combustion. Also how many miles are on the car? How do you drive the car? Does the engine see higher RPM's at all? If not, maybe doing an "italian tune up" might work if you drove around hitting higher rpms for a little bit. This along with the injector cleaner may help.
Josh

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Re: Emissions trouble (high CO)

Post by OTTERMATIC »

Hey, just saw your response! Sorry for the delay.

My first emissions results, when I bought it (all measurements in GPM):
HC 0.5988/1.5000 (pass)
CO2 417.2267 (no limit, no fail)
NOx 1.8297/3.5000 (pass)
*CO 19.4713/15.0000 (fail)*

My most recent test a few months ago, after some work (in GPM):
HC 0.3256/1.5000 (pass)
CO2 393.1508 (no limit, no fail)
NOx 0.5510/3.5000 allowed (pass)
*CO 16.3340/15.0000 allowed (only fail)*

So the CO2 has been the only failing point, but I notice CO2 is also pretty high compared to the others in both results. Between my first test and my second, I did:
Oil change and filter
Sparkplugs and wires
New O2 and Cam sensors (fixed the check engine light for both)
Cleaned MAF and throttle body (fixed check engine light for MAF, no more lights.
I tried out D-Check but didn't really understand what it was doing yet, so I'll research that.)
Cleaned up the engine, degreased a bunch of the oil off, seemed to run a little smoother afterwards
Replaced exhaust header gaskets, reduced exhaust smell in cabin
Sealed some exhaust leaks with JB weld
I'll add more as I think of it.

Right now, the issues I'm having are that it still smells a bit like exhaust while it's running. The exhaust smells a little gasoline heavy. The engine and transmission both leak oil, and I haven't done anything with the cooling system. It gets about 20mpg, which feels... okay. I do mostly city driving, and I try to keep the RPMs low because I know it needs new gaskets and timing and everything. It's an AWD wagon with the 5MT. 285k miles. I just did another oil change and put in a new air filter, fuel filter, another oil change and some fuel injector cleaner.

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Re: Emissions trouble (high CO)

Post by Legacy777 »

Thanks for the additional information.

You should try and get the exhaust leaks fixed if possible. You shouldn't be having exhaust smell in the cabin. It's possible the catalytic converter is not working properly and that's why you're not passing....along with just overall age/engine health. Have you done a compression or leak down test on the engine? That would help tell you whether the engine itself is still in good working order or if you have other issues internal to the engine that need to be addressed.
Josh

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1990 Legacy (AWD, 6MT, & EJ22T Swap)
2020 Outback Limted XT

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Re: Emissions trouble (high CO)

Post by OTTERMATIC »

I ran D-Check mode and it blinked at a steady rate while driving (suggesting no trouble codes found), but then I used the regular test mode and the MAF sensor code came up again. Looks like the MAF might be bad and cleaning wasn't the solution. I'll try changing that next and update if that lets me pass emissions.

Edit: I somehow didn't see your second response. I haven't done a compression or leakdown test on the engine yet. I haven't been able to locate the other exhaust leaks either, but I'll be starting by replacing gaskets as I can afford them. Is there a way to check the cat to see if it's plugged up or damaged? The car has suffered a lot of rust.

One extra thing, I noticed a hole near my throttle body and I can't tell if it's supposed to be there. Let me know what you think: https://imgur.com/a/DxgztGY

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Re: Emissions trouble (high CO)

Post by Legacy777 »

Regarding the MAF I'd suggest checking the wiring from the MAF to the ECU and the MAF with the multimeter if you have one. Below are the pages from the factory manual.

https://main.experiencetherave.com/suba ... sting1.jpg
https://main.experiencetherave.com/suba ... sting2.jpg

That hole in the TB should just be a casting type thing. If you can see down into the throttle body and there's a hole with the threads there is a screw there. That was an older setup on the 90 model year for throttle body calibration. They ended up eliminating that screw but didn't change the casting form. You can see what it used to look like in the link/images below.

https://main.experiencetherave.com/subaru/images/TB/
Josh

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1990 Legacy (AWD, 6MT, & EJ22T Swap)
2020 Outback Limted XT

If you need to get a hold of me please email me rather then pm

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Re: Emissions trouble (high CO)

Post by OTTERMATIC »

I'm so dumb - I left my cheap multimeter in my car, and the screen/case literally melted. It's just giving me random numbers and now it won't turn off lol. I went ahead and ordered a new MAF sensor because, well, it'll either fix the problem or I can return it and get a real multimeter if it doesn't.

Thanks for calming my worries about that hole in the TB by the way!

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Re: Emissions trouble (high CO)

Post by Legacy777 »

No worries.

Let us know what you find out.
Josh

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wtdash
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Re: Emissions trouble (high CO)

Post by wtdash »

Before you install the new MAF, note that the JEC/Autecs GREEN label plastic housing '92+ all used the same MAF (except turbo) thru '99 Legacy, Impreza and '98 Forester ('99 was Legacy OB/GT only). Find another used one. MAF will frequently cause a stall at idle, if (going) bad.
GL

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Re: Emissions trouble (high CO)

Post by OTTERMATIC »

wtdash wrote:
Sat Aug 22, 2020 7:55 pm
Before you install the new MAF, note that the JEC/Autecs GREEN label plastic housing '92+ all used the same MAF (except turbo) thru '99 Legacy, Impreza and '98 Forester ('99 was Legacy OB/GT only). Find another used one. MAF will frequently cause a stall at idle, if (going) bad.
GL

(HI Josh!)

I'd already ordered a new one but it was only $20 and I've been having trouble finding a used one. However, now I've installed the new MAF, and I'm having a new stalling at idle issue. The RPMs flutter on startup and won't stick anywhere. I have to rev it hard to keep the engine alive, because if it dips below 2000 it pretty much immediately dies.

I was wrestling with the air intake hose, so I'm wondering if a vacuum tube just got knocked loose. What are the odds that a brand new MAF is bad? I just now pulled the negative battery cable and I'm going to let it sit for a couple of hours to see if resetting the ECU will do anything.

Edit: It was indeed a vacuum hose! I found a hose had slipped off the air intake when I was installing the MAF, plugged it back in and now it's running nice and smooth. Little bit quieter and it's hard to tell because my sense of smell is garbage, but the exhaust smells slightly cleaner. I'm going to take it in for emissions testing on Monday, fingers crossed it finally passes!

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Re: Emissions trouble (high CO)

Post by wtdash »

Good luck. :-)
Turbo Subies:
'87 GL-10 Turbo - SOLD
'90 BJ EJ22T/DOHC & 5speed swap - SOLD
'04 FXT, Forged internals, VF39, STI TMIC, Cobb AP- SOLD
'93 Legacy SS - 5-speed, SOLD :-(
'02 WRX -SOLD
'96 BD-turbo'd-SOLD
'98 SF - NA-T

Legacy777
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Re: Emissions trouble (high CO)

Post by Legacy777 »

Yeah, let us know how it goes today.


Hi Todd :)
Josh

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Re: Emissions trouble (high CO)

Post by OTTERMATIC »

Update: Took it in for emissions today and failed hard.

Emissions results were:
HC GPM 0.4478/1.5000 (passed)
CO GPM 21.6857/15.0000 (failed)
CO2 GPM 443.0862 (no pass/fail)
NOx GPM 0.9835/3.5000 (pass)

Since my last test, both HC and NOx have improved slightly, although they were already passing. Both CO and CO2 have gotten significantly worse.

After my last test and before this one today, I:
Changed the oil
Topped off transmission fluid (it leaks)
Topped off coolant (was leaking before but seems to be holding in warmer weather and now that I'm driving it less)
Replaced MAF sensor
Replaced Fuel filter
Replaced air filter
Replaced oil filter
Ran "fuel injector cleaner" through the gas tank as instructed (didn't expect it to do much but it's basically a little bit of ethanol, can't hurt)
New tires and alignment

This is in addition to the O2 and Camshaft sensors, and the sparkplugs/wires that I replaced prior to my previous test.

It gets worse. While testing, my car started smoking a significant amount out the engine bay (although they passed me on smoke lol), and absolutely pouring oil out the bottom while it was on the dyno. It drives like normal and there's no lights, but the transmission appears to be leaking a significant amount. And plus, the smoke, it's done that occasionally and on every dyno test before, but it was so much thicker and more abundant than before. I'm a little worried about it.

Here's a link to an Imgur album of the leak and a couple of suspicious bolts/holes. https://imgur.com/a/Krsjpqu I'll post this over in the drivetrain section if you want me to, since this isn't an emissions issue.

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Re: Emissions trouble (high CO)

Post by jefferson »

That's one serious leak. Are you sure you didn't overfill it? I have no idea, but would a new pcv valve have any effect on anything?
91 Black SS 5spd. Edm lights, wrx gauges in dash, 45 degree airbox, cryoed drilled and slotted brakes. Invidia divorced downpipe with custom stainless exhaust. To be installed, aluminum a-arms, manual belts, awic.

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Re: Emissions trouble (high CO)

Post by OTTERMATIC »

jefferson wrote:
Wed Aug 26, 2020 1:28 am
That's one serious leak. Are you sure you didn't overfill it? I have no idea, but would a new pcv valve have any effect on anything?
To be honest I think I did. Nothing was showing on the dipstick, so I just kept pouring until I saw it at the L. Now I'm wondering if it's supposed to be warm before checking the level/filling. I didn't measure how much I put in very accurately. Considering the transmission felt like normal (kinda loose and crappy but functional), I don't think anything actually broke. I'm wondering if the smoke came from spilled oil.

As far as the PCV Valve, actually, maybe. I looked it up, seems like it can potentially cause the engine to run too rich. Not a consistent cause/effect though so I'll add it to the to-do list, but I think I need to keep searching.

I found something strange in my emissions testing, here's a picture of the graphs: https://imgur.com/a/dGWbyRQ
Everything seems to spike around 30mph specifically. You can see that all four measurements spike whenever the speed crosses 30mph, and NOx and HC both drop right after and stay mostly under a certain threshold.

CO2 and CO on the other hand seem to peak with almost every acceleration. It's really hard to tell exactly what's going on because I don't know how they're shifting it, but it looks a little like it's spiking after every shift. CO2 drops after what I think is 5th gear (when it reaches 50mph). All this really tells me there is some issue happening in higher RPMs just before a shift.

But I don't know what that indicates. Any ideas?

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Re: Emissions trouble (high CO)

Post by Legacy777 »

So I have a couple comments for you.

Regarding the transmission....the automatic transmissions have two separate dipsticks, one for the AT fluid and one for the differential fluid. The differential dipstick is on the left (passenger) side when standing in front of the car and the automatic transmission dipstick is on the right (driver) side when standing in front of the car. The differential dipstick is supposed to be read when the car is parked on a level surface and the engine is OFF. The automatic transmission fluid is supposed to be checked when the engine is RUNNING and you are parked on a flat surface and the engine and transmission are at normal operating temperature. Just before checking the AT fluid you should slowly cycle the gear selector from P to 1 and then back to P. Turn off all the accessories, AC, etc, leave the engine RUNNING, pull the AT dipstick out, wipe it, and then reinsert and remove to check the level.

With all that being said, which dipstick did you check and did you follow the procedure above when checking the level? If you didn't follow this then you may have either overfilled the transmission or put incorrect fluid in the wrong spot.

Regarding the PCV valve, I would recommend replacing that....I don't know if that will cause your issues but can't hurt.

In your picture, that hole is just a hole for the alignment pin/dowel. There is not supposed to be a bolt in there.

The emissions graphs....without knowing the throttle position it's hard to say whether that blip is important or not. It could just be a transient spike during a shift or if the throttle position changed unexpectedly.

Forgive me if you already stated this, but how many miles are on the engine/car? It's possible the catalytic converter may just be bad.
Josh

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1990 Legacy (AWD, 6MT, & EJ22T Swap)
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Re: Emissions trouble (high CO)

Post by OTTERMATIC »

It’s the five speed manual, so I’m not sure how different that is, but I only checked the dipstick on the passenger side at the top. I think you can see it in the pictures I posted.

For mileage, it’s almost at 286,000. And I think it was run pretty rough for most of those miles, I’ve only had it for the last 2,000 or so. I started reading up on catalytic converters and they can cause a lot of the issues I’m seeing, more than any other singular part. So it looks like that will be the best thing (along with the PCV and a compression test). Anybody know a good aftermarket cat that fits these cars? I’m recently unemployed and pretty strapped for cash right now.

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Re: Emissions trouble (high CO)

Post by Legacy777 »

Ok, if it's a MT then you can disregard my comments above. To check the MT you would park on a flat surface and check without the engine running. Are you able to see where the leak is coming from on the transmission? Does it smell like gear oil or engine oil? If it's coming from the bell housing and smells like gear oil it's likely the input shaft seal on the transmission.

If you're looking for a replacement the rear cat on Rockauto is around $200. You might be able to find a universal cat and have an exhaust shop weld it up. I'm not sure if that would be any cheaper.

I looked up your VIN and just to confirm you have a 1993 L Wagon 5MT correct?
Josh

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Re: Emissions trouble (high CO)

Post by OTTERMATIC »

That’s spot on, it’s specifically the 25th Anniversary Edition (based on the little bit of that sticker left). 5MT and AWD with the naturally aspirated EJ22. Despite the emissions trouble, I love this car. I’ve owned a good variety of sedans and sports cars before, but I’ve had way more fun in this than anything else.

As far as the leak goes, I’m not able to tell where the leaks from. I’m not able to smell any burning fluid while driving, but my sense of smell is nearly non existent.

I can weld actually, so I’m looking at picking up some universal cats and just welding them in (then recycling the old cores for a bit of money back). I bought a stethoscope to help narrow down any exhaust leaks as well and I’m hoping to try it soon when it cools down.

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Re: Emissions trouble (high CO)

Post by Legacy777 »

If you dip your finger in the oil on the ground are you able to smell anything in comparison to the new gear oil?
Josh

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Re: Emissions trouble (high CO)

Post by OTTERMATIC »

Unfortunately not, can't smell regular oil anyway. I put a pan down and caught a bit, confirmed it was for sure transmission gear oil because of how thick it was. It was very dark black though.

I also noticed a persistent tapping sound that seems to be coming from the passenger side of the engine, maybe towards the bottom of the block. And I shouldn't say it's persistent, it comes and goes, but really consistently. It'll stop tapping for a few seconds, then tap for a few seconds, and back and forth. Here's a video:https://youtu.be/tWh3OGpDBtA

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Re: Emissions trouble (high CO)

Post by jefferson »

That's your lifters making that sound. Pretty common. Nothing I have done seems to get rid of it.
91 Black SS 5spd. Edm lights, wrx gauges in dash, 45 degree airbox, cryoed drilled and slotted brakes. Invidia divorced downpipe with custom stainless exhaust. To be installed, aluminum a-arms, manual belts, awic.

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Re: Emissions trouble (high CO)

Post by OTTERMATIC »

Glad to know it’s expected, thanks. This is my first Subie and first time really working on a car, so I’m new to a lot of things.

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Re: Emissions trouble (high CO)

Post by Legacy777 »

As Jefferson noted that sounds like the hydraulic lifters. It's possible you could have one that is maybe not staying adjusted as well as others. If you rev the engine a little does the noise change or go away. That could be an indication of slightly lower than desirable oil pressure.
Josh

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Re: Emissions trouble (high CO)

Post by OTTERMATIC »

Update! While I have the engine out of the car, I decided to pull my whole exhaust to figure out where the trouble spots are. It’s not looking great. I had to cut several bolts off due to the heavy rust. It’s difficult to inspect the cats through the small holes but they don’t look as bad as I expected.

With how horribly rusty everything is though, I’m considering replacing the whole thing. Though it looks pretty pricey. My front cat also looks different from most of what I’m finding for sale, it looks like a lot of Subaru exhausts have the front cat bolted into place (with both headers joining like a Y), whereas mine has both welded into the cat. So I’m a little at a loss where to go next from here.

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