240: Just failed CA smog, high NOx

[GeneralBurrito]

The results

Already reinstalled the stupid intake preheater. I'll be putting the timing from 6 back to 12 when I do my oil change in a couple days. My cat is a Walker 81111 that's only been on for like 8 months, but probably only gone through 1.5-2k miles, everything in the test seems perfect except high NOx at 25mph. O2 sensor has been replaced earlier this year, spark plugs and wires are less than a year old, and I'm running yellow injectors from an 850. I disconnected the battery for 15 mins to reset the O2 sensor.

Only thing that might have affected the test was that I live not too far from the smog place, so I think I didn't let the car and cat get to proper temps by driving less than 5 minutes. That and my ignition timing was way off.

[wennstroma]

Retarded timing actually helps lower nox.

I don't have experience with that specific cat, but most of the non original ones I saw when I worked down there had to be replaced each smog test to pass on nox (even the small ones Volvo sells now aren't much good). Your gasses make it look like the engine is running okay.

I would advance the timing the minimum amount to pass their check and then drive it over in a low gear to get the cat hot so it has a better chance of passing, and/or see if they'll let you drive it right before they put it on the rollers. If they let it sit and idle for a few minutes, you won't have much of a chance.

[2turbotoys]

I would advise registering the car in a state with realistic emissions laws. Can you register as an antique? That's what I did in PA, no emissions or inspection ever again.

[GeneralBurrito]

I was reading around and apparently retarding ignition timing too much actually worsened emissions. I'm planning to put it back to 12 since I got the smog check paper right before I bought the car and it passed perfectly back then on 12 degrees, the cat imploded on itself a couple months after I bought it and started driving, so it passed smog 2 years ago on a nearly failed cat.

[Redwood Chair]

Is it box stock and stage zeroed?

If not why not?

[philski o'flood]

this is your LH2.2 car? set the timing back to normal, everything else looks great

[GeneralBurrito]

Yes it's lh2.2. I think timing was the main culprit along with not driving it long enough because I didn't mess with the engine much but replace to newer parts. Exhaust and ignition should all be at stage zero. I don't think anything is wrong with the fuel system, the car starts right up every time. Not sure if the 850 yellow injectors did much, but I have been getting better mileage over time.

[planetman]

Can you post a picture of the print out with ALL of the readings?

[GeneralBurrito]

Originally Posted by planetman

Can you post a picture of the print out with ALL of the readings?

It's a link disguised as "The results" in the first post

[Otto Mattik]

Sell car cheap to a guy in Minneapolis

[122power]

Retard timing as much as you can within the limits. Plug vac adv line to dizzy. It adds way to much timing. Should drop it by 300 points ish. Check for vac leaks also. Egr car?

[GeneralBurrito]

Non egr as far as I know. Don't really know how to check other than it not having a tube coming off the exhaust towards intake.

[IansPlatinum]

From engineering school:


Low HC, no CO and high NOX indicates an overall lean running condition.

[ZVOLV]

The cat may be no good. Or wasn't lit off yet. Drive it hard and then leave it running when you get to the station.

Another trick is run a good amount of E85 in the tank.

Ignition timing too far advanced will increase smog. There are issues with 2.2 and that vacuum system at the ignition box.

[IansPlatinum]

Here's another graph to help you understand your probable Air/Fuel mixture

[GeneralBurrito]

The O2 sensor might not have been working properly too since I swapped out the alternator to a 100A hoping to do an eFan swap in a few days. The battery was disconnected for a while so it may have been reset. I didn't drive it between then and when I did my smog. Would a reset O2 sensor have been what made the car run lean?

[GeneralBurrito]

Originally Posted by ZVOLV

The cat may be no good. Or wasn't lit off yet. Drive it hard and then leave it running when you get to the station.
Ignition timing too far advanced will increase smog. There are issues with 2.2 and that vacuum system at the ignition box.

It may have been that I didn't let the cat get to operating temps, I just drove straight from my house to the smog place, less than 5 minutes. I also read in another smog thread, thanks to philski o'flood, that plugging the vacuum line going into the black box on the passenger side fender drops NOx massively because it prevents the system from advancing the timing.

[ZVOLV]

I recall that post by Philski also. I would go with that.

High octane fuel helps too. I don't know how much Ethanol to recommend, but I would maybe try almost half of the fuel in the tank as E85.

[GeneralBurrito]

Looking up E85 gas on Google maps shows some pumps near me. Is it fine to mix E85 with 87 gas? I thought you'd need bigger fuel pumps and all that to handle it.

[ZVOLV]

I put about 5 gallons in my 1991 740 Turbo before a smog recheck. I don't have the sheets, but I wanna say it helped.

Those aftermarket cats go bad quickly too. If it really comes down to it, slap on a fresh kitty and it should pass.

[GeneralBurrito]

Walker has a 5 year/50,000 warranty though. Since the new cat was put in, I don't think I even out 2k into it. It's just a daily driver to and from school.

[Duder]

Mr. Burrito: what model year is your 240? Automatic or manual?

I wrote up a whole treatise on getting an '83 DL to pass smog a few years ago. Also a history of how the limits have changed over time. Might help in this situation: http://www.dailyturismo.com/2013/09/...-it-legal.html

[ZVOLV]

Good luck getting warranty $. The exhaust shop that did mine blew me off when I asked for a warranty and blamed the car.

5 gas analysis is tricky. The 25mph test is actually HALF the load of 15 mph. I see you passed fine at 15mph. And your ignition timing was too far back,so it doesn't look like timing is the issue. You have almost no CO which could mean lean, which also increases nox. Air leaks or injectors could cause a lean condition. You do have the incorrect injectors.

[GeneralBurrito]

It's a 1987 240 DL, manual.

I still have the old single hole injectors that I could slap back on. They may not be as clean as the 850 yellows, but they still work.

[Duder]

Originally Posted by GeneralBurrito

It's a 1987 240 DL, manual.

I still have the old single hole injectors that I could slap back on. They may not be as clean as the 850 yellows, but they still work.

Ok, I suppose that explains the 724ppm limit for NOx at 25mph then. My reference is early '80s cars which have slightly higher limits. There's no way of looking this up at all, other than comparing notes with other people's test reports.

For an 1983 240 DL w/ manual, here's an illustration of how NOx changed over time (well, up until late 2014 anyway when I made the graph).