sdk1m

Hi everyone, I have a 2004 Lancer LS with 214k miles, no mods or anything. I need to pass a smog check before next week and am looking for some advice. First, I'll explain my situation with my car to give you all a better understanding.

I first attempted to smog 6 weeks ago and passed the visual inspection and emissions test but failed the functional test due to the CEL with code P0135: O2 Sensor Heater Fault (Bank 1 Sensor 1). Apparently my CEL lightbulb was out so I didn't know. I will provide the emission test results to compare with my most recent smog test:



I noticed my NOx was already very high at this point (tested at 15 mph) but was barely able to pass. All my other results seemed relatively good. So I thought all I had to do was fix my code and I'd be fine. I had my sensor replaced and brought it back to find another code P0421: Warm Up Catalyst Efficiency Below Threshold (Bank 1).

Over the next month or so, I spent a lot of time researching and deciding what to do with my car. Keep in mind that I have work and other priorities to address so I couldn't work on my car too often. I was able to remove the code by using the spark plug anti-fouler fix to pull out my rear O2 sensor and my CEL has been off ever since. I got an OBD-II scanner to clear/check for codes and test my sensors and they're both fine, so I'm pretty sure my main issue is with my front catalytic converter. But I can't afford to replace that right now.

I also ran half a can of Sea Foam (aerosol) through my air intake, a little under half a can (liquid) in my crankcase and the rest (liquid) in my gas tank. I thought this would help me with my emissions and I needed to clean out my car anyway. I changed my oil after that and my spark plugs from NGK Iridium (BKR5EIX-11) to NGK Platinum (BKR5EGP). I drove about 4000 miles since my last smog check and about half of it was after changing my plugs.

Just today I brought it in for a smog check and was hoping it would pass, but this time I failed the emissions test (passed the visual and functional tests though). Here are the test results:



As you can see, my NOx levels have increased significantly, and pretty much everything else got worse. I'm thinking it has to do with all the driving I did since my last test, along with my front cat not performing well. I was wondering if it had anything to do with changing my spark plugs too? I read somewhere that spark plugs with the wrong heat range can increase the cylinder temperature and thus increase the NOx as well?

Anyway, I need to figure out a way to reduce the NOx levels (relatively quickly and inexpensively aka I can't afford a new cat) to at least pass smog by next week. I'm considering running the rest of my Sea Foam (aerosol) through my air intake again and getting colder spark plugs to reduce the cylinder temperature. I'm still relatively new to cars and don't completely understand everything so please correct my if I'm doing anything wrong. Any advice will be much appreciated!

hoino11

I'd definitely get rid of the fancy plugs, because that'll be a good part of the issue. Service manual recommends either NGK BKR5E-11, Denso K16PR-U11, or Champion RC10YC4 which are all copper plugs if memory serves. I tend to lean towards the NGKs myself cause I've never had an issue with them and they last a good while. Luckily a set of them is under 15 bucks most places which is way cheaper than platinum or iridium ones. I'd say since the car has that many miles on it that there are a couple things that will help the emissions problem. The most likely culprit is the EGR valve and the good news is that it's easy to remove plus there's no fluids involved. If you remove the airbox it's the golden topped spaceship looking thing that's held onto the intake manifold by two (12mm?) bolts right under your throttle body inlet. Once it's off spray it down the ports with good brake cleaner a couple of times and let the soot crap pour out before wiping it down with a paper towel. Once that's done, push on the valve in there to make sure it isn't stuck, then if all is well you can put it right back on with the old gasket if it's still decent enough to reuse (if not you'll need a new one but they're dirt cheap). That should be enough to pass you, but if not you can just take the whole intake manifold off and scrub it down on the inside. The EGR cleaning and spark plug change should be enough though, so let me know how it goes

meckert

iTrader: (11)

I don't know anything about you lancer-- so let me provide you with this tidbit--if it has a distributor and only if--- back your timing down at the dist. NOx and CO are inversely proportional. So as you decrease nox, co will climb-- as you back the timing down. I had the same issue with a Nissan but mine was in the tune-- I got thru running at tdc at idle..
Again-- don't know about your lancer-- but if this helps. Check magnaflow oem cats out as well.

sdk1m

Thanks for the advice bro. I did some more research, cleaned out my car and took it in today and good news, it passed!

Here's what I did for anyone who might run into a similar problem:

Cleaned out my EGR valve (which had a 1-2mm thick black layer of carbon buildup coating the insides) like hoino explained, with some carb/choke cleaner. Made sure I got everything out and sprayed the valves it's attached to as well. Pretty sure this made the biggest impact.

Cleaned out my Mass Air Flow sensor (between the air filter and air intake boot), sprayed it down with some MAF sensor cleaner for a richer air-fuel ratio. I suspected I was getting a lean air-fuel ratio which would increase combustion temperatures, resulting in higher NOx levels. I already replaced my front O2 sensor so I know that wasn't an issue.

Wiped down my spark plugs (which had some oil leaking into the wells) and swapped out my spark plug wires. Didn't get to switch out my spark plugs to copper ones but just did what I could to avoid any potential problems with igniting the air/fuel mixture.

Ran the rest of my Sea Foam aerosol spray through my air intake and poured a bottle of Lucas Oil Deep Clean Fuel System Cleaner in my fuel tank, filled it up, and drove to empty over a few days. Not really sure how well this works, but what the hell, might as well try cleaning out my combustion chamber, fuel injectors, etc. The bottle also mentions it "Reduces NOx emissions" but who knows if it's true haha. I actually noticed a much smoother idle after all of this though.

Last piece of advice I read that I did not think to do the first times, I drove on the highway for about half an hour before taking it to the smog station to warm up my catalytic converter and left my car idling until the guy tested it. Pretty sure it helped in allowing the cat to function properly during the test.

Here's the emission test results from this morning:


NOx levels at 15mph reduced to even lower than my first test (enough to pass!!), and at 25mph about half of the previous test. HC and CO levels went up at 15mph but didn't change much at 25mph. Concluding from this, I take it that my cat isn't running very efficiently and I may need to replace it later. But I'm just glad I passed and I have one less issue to deal with now Thanks again for the help and leading me in the right direction!

hoino11

Nice man, good to hear that you didn't get screwed by the smog test after all! Gotta love how dirty those egr valves can get, not to mention everything else emissions-wise for that matter. So did you fill the streets with white smoke when you did the seafoam pretty bad? And how often do smog tests have to be done down there?? We don't have to do smog tests in marion county so I'm just curious