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Passing emissions with an L28ET


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Hi Folks, I thought I'd share my experience with getting my car through emissions in the state of Oregon. I'm required to only pass idle emissions at no more than 300ppm hydrocarbon and not higher than 1% carbon dioxide. I wasn't able to pass until I made the following changes. I wasn't ready to add denatured alcohol or other extreme measures unless I had to. Keep in mind I have programmable EFI and a larger camshaft. This also assumes all engine components are in good working order.

 

1) Tune AFR's for 14.3:1. I found that anything higher produced a failed emissions test. My previous belief was best emissions were achieved at 14.7:1.

 

2) Run the factory spark plugs NGK BPR6ES-11 at .050 gap. I normally run colder NGK BPR7ES at .030 gap.

 

3) Set initial and idling ignition timing to 10deg BTDC.

 

4) Make sure idle is stable and that your O2 sensor is set to make small corrections.

 

3) Set idle up higher than normal but not higher than 950 or so.

 

After I did all this I passed with flying colors. :mrgreen:

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Good info John!

 

My '82 has to pass emissions again before December too. I left the stock manifold, etc. on so (hopfully) I should have no problem passing. Then I'll have up to two years to work out any kinks in the mods I'm planning to do.:burnout:

 

You probably knew this already, but if we don't pass, we can get only one 30-day trip permit per year. At least we don't have to let them drive our cars on the dyno anymore!

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  • 3 weeks later...

I finally passed!!

 

It failed the first time under CO% was 1.6% at idle and 2% @ 2500RPM. Both have to stay below 1%.

 

I lowered the fuel pressure from 38 psi to 36, installed a new set of NGK BPR6ES-11 plugs and it worked! Since I was at only 0.36% CO at idle, they didn't even have me go to the 2500 RPM test.:hs:

 

The icing on the cake was that Baxter Auto charged me only ~$9.00 ($1.45 per plug). List price is $4 per plug?!

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1) Tune AFR's for 14.3:1. I found that anything higher produced a failed emissions test. My previous belief was best emissions were achieved at 14.7:1.

 

Richer than 14.7 produces more CO, leaner than produces more NOX. 14.7 is where they cross... the lowest volume of both. At least, that's how I understand it.

 

Your suggestions also normally work for stock-cammed NA L28's (even in open loop).

 

Thanks for sharing. I kept forgetting to ask you how you faired.... that 11.3 pass had me distracted :D

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I finally passed!!

 

Congrats Hugh. It's always a sigh of relief when I pass emissions. :D. I keep forgetting to request the Baxters discount. Thanks for the reminder.

 

 

Richer than 14.7 produces more CO, leaner than produces more NOX. 14.7 is where they cross... the lowest volume of both. At least, that's how I understand it.

 

Your suggestions also normally work for stock-cammed NA L28's (even in open loop).

 

Thanks for sharing. I kept forgetting to ask you how you faired.... that 11.3 pass had me distracted :D

 

I agree that 14.7 should produce the best emissions but when I tuned for 14.3 I breezed right though without having to do the 2nd idle test. I'm pretty sure my O2 is calibrated properly so I'm not sure what to think. Maybe it was the other changes that made the big difference and richer idle was not enough to be a problem. :hs:

 

 

 

I plan to move leave Kansas and move to Oregon after college. Is there no antique exemptions in Oregon? This will be the one thing I miss about KS, we can renew our registration through the mail, one initial mechanical inspection and then thats it.

 

If you don't live in a DEQ area (outside of the major cities) you just have to pay your registration. If you live in a DEQ area you will need to do an emissions test for any car 1974 and newer. Unfortunately there are no antique exemptions.

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  • 2 weeks later...

Best thing you can do to pass an emissions test is to change the oil 24 hours before you take your car to be inspected.

 

One of the biggest causes of an emissions failure is old oil through your PCV system. Your old, broken down, contaminated, and sludgy oil goes back through your PCV valve into your intake causing your mixture to be contaminated, which is then burned in your engine, causing higher emissions.

 

 

Just another reason to change your oil regularly:mrgreen:

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I've found that AFR's at idle need to be richer (as did Nissan---that TPS idle contact RICHENS the fuel curve for idle operation!). When you run 14.7, the HC's go up due to Misfires from what I've seen.

 

This is an uncatalyzed set of readings, correct? What were your readings, anway---did you make the numbers by a wide margin, or just squeak by. I'm curious to see the actual numbers' results. I have to dig up the last legal smog test I did on my 73 down here in CA. I passed the tailpipe, but still failed the visual...

 

This summer, I will be getting a full Engine Analyzer, same unit they used in Delaware to do Emissions Testing up until a couple of years ago. Full diagnostic capabilities, as well as two-gas analysis (CO & HC) as well as two cans of the Cal and Span Gas! I will be set to do the old Idle-2500 tests like the old BAR-90 standard. If I can get the car to pass idle-2500, it's ready to go to the dyno and not set off any of the HIGHWAY mounted Emissions Monitoring Points down here...

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I had to pass my work truck. I put on a new CAT. Here is a little vid of the truck with straight pipes.

 

Nice!! Next is big lopey cam right? :D

 

---did you make the numbers by a wide margin, or just squeak by. I'm curious to see the actual numbers' results.

 

I made it though by a small margin but I wouldn't say I just squeaked by. This is my third time through. The first three times I didn't pass 1st idle so they made me do the 2500rpm run up then tested for 2nd idle. I was surprised to see that emissions get much better on the 2nd idle test even though I didn't pass. I went home and figured out the issues and passed the next day on just the 1st idle test.

 

Here are the results for the 4th test that passed.

77Zemissions10_11_07.jpg

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  • 3 weeks later...

Great info jgkurz! Though I would like more info about the testing.

 

What were you using to measure the AFR? I assume the smog machine?

 

Also, did you have a cat installed?

 

 

I personally think that you could get nearly any street modified vehicle to pass with the right scenarios. It's all just a matter of dialing in the AFR and the timing and tweeking other things if they need to be.

 

Things like the spark plug and gap shouldn't even make a big enough difference compared to the AFR.

 

I just got my CRX to pass WITH A MISS and a super super lean mixture. (16+ ranges)

 

How did it pass? I honestly have no clue, but with super retarded timing and reving the engine as hard as possible pretest to keep it hot we passed with CO at .00% at 15pmh and .01 at 25mph, NOx was within 5% of max number, and max HC at 25mph was 108 and we measured 107... :D

 

My next big challenge will be getting my 200k+ L28ET swap to pass the L28E emissions with what looks to be a gutted cat. Fun fun fun

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My AFR's are read by the FJO WBO2 controller built into my EFI. I consider it very accurate.

 

I do not have a catalytic converter. My car is a Federal 1977 and did not come with one.

 

Using the hotter OEM spark plugs plugs with a wide gap definitely help me pass emissions testing as compared to my normal plugs.

 

 

Great info jgkurz! Though I would like more info about the testing.

 

What were you using to measure the AFR? I assume the smog machine?

 

Also, did you have a cat installed?

 

 

I personally think that you could get nearly any street modified vehicle to pass with the right scenarios. It's all just a matter of dialing in the AFR and the timing and tweeking other things if they need to be.

 

Things like the spark plug and gap shouldn't even make a big enough difference compared to the AFR.

 

I just got my CRX to pass WITH A MISS and a super super lean mixture. (16+ ranges)

 

How did it pass? I honestly have no clue, but with super retarded timing and reving the engine as hard as possible pretest to keep it hot we passed with CO at .00% at 15pmh and .01 at 25mph, NOx was within 5% of max number, and max HC at 25mph was 108 and we measured 107... :D

 

My next big challenge will be getting my 200k+ L28ET swap to pass the L28E emissions with what looks to be a gutted cat. Fun fun fun

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There's also a chance if in your state NOx was tested for that the wide gapped spark would result in higher NOx numbers.

 

Just an assumption, maybe wrong maybe right. In my experience it's very hard to do anything that will adjust just ONE aspect of emissions, and the more things they test for (like 3 gasses here in CA) the harder it is to find that balance point.

 

If you put on a cat for test passing purposes and ran a test pipe the rest of the time I'd guarentee you'd have an easier time passing. But you passed, that's all that matters.

 

 

BTW, the law is being put into effect right now in CA, but now we have to pass a test on the EVAP system that pumps nitrogen into the gas tank and checks pressure stability to varify there are no leaks in your fuel system.... greeeeeat.

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  • 4 months later...

Who's doing the testing is just as important as the car.

 

I've seen tons of cars failed because the inspector was a chump.

 

If you get some guy who sets the car aside and lets it idle for 45 minutes, then it will most likely fail.

 

If you live in a state in which they run your car on a dyno, an inspector who doesn't have smooth throttle technique when responding to the speeds requested by the test proceedure can easily cause the car to fail.

 

Former Virginia Emissions inspector.

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Who's doing the testing is just as important as the car.

 

I've seen tons of cars failed because the inspector was a chump.

 

If you get some guy who sets the car aside and lets it idle for 45 minutes, then it will most likely fail.

 

If you live in a state in which they run your car on a dyno, an inspector who doesn't have smooth throttle technique when responding to the speeds requested by the test proceedure can easily cause the car to fail.

 

Former Virginia Emissions inspector.

 

Interesting. Thanks for your informed response. :icon7:

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That's a very good point howlermonkey. The inspector can make or break your testing. I tend to recommend people to go to shops that I know aren't very busy as there's a good chance they'll take the car right away.

 

Ideal situation you drive your car hard for a good 15 minutes, and park and get the test done within 10 minutes.

 

I'm about to go do a mock test this week on my new 80', we'll see how much the burning oil effects the numbers...

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I may as well relate my emissions testing experience...

 

I learned this from my old man on our 87 E-250 conversion van (351 Windsor HO, 4-bbl) and in retrospect, apparently this engine had been running with the headgaskets reversed, or swapped, or somehow inverted (they tore the engine down a year or two ago, this story happened over ten years ago.)

 

We could NOT get the thing through emissions for BEANS, and we do not have incredibly strict standards. We put a rebuilt carburetor on there, replaced the catalytic converter, and still flunked. My dad's final effort (he had tried before changing the carb and cat, but not since) was to totally run one gas tank dry, and put a gallon of Denatured Alcohol from Home Depot in. We got in the van, drove to the station.. and right past it, to the highway it was off of. (Howlermonkey: this was at Beeline and Military, circa 1994) He got out past the fire station, and we were in the middle of nowhere a mile away from the inspections place. 4-5 miles at 85 westbound, U-turn, 4-5 miles at 85 eastbound, switch over to the alcohol a little bit before he slowed down. Got in line at the inspections place (short line, did this early on a tuesday) still burning alcohol.. I think there was ONE factor that wasnt virtually ZERO, and it was like 4 ppm or ppt or .004%.

 

Sorry I can't recall the specific units and measurements, but FL hasn't had emissions testing since 1999, and I only ever had to personally do it on one of my cars once.

 

Anyhow, Alcohol is perfectly safe to run in any engine as a fuel, as long as it doesnt SIT in the fuel lines, pump, carb, rail, etc. The END of my story is, we immediately filled that fuel tank (gee, at like, $1.03/gallon, too) and drove 40 miles away to go to the beach that day, and 40 miles back... and so on until that tank was empty, at which point we filled it and ran it dry AGAIN. I cannot vouch for its safety in turbo cars, but I know its perfectly fine in fuel injected vehicles. High-performance engines MAY experience tuning issues with this; again, that is beyond my experience. I certainly hope someone with more knowledge to back me up can answer those questions, but to me, this is the ultimate "trick" for passing emissions testing in a tough vehicle.

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Interesting trick.

 

I'd like to relate a small tidbit from having to pass emissions a few times with my L28et. I've never had a problem with the loaded test on the dyno (in AZ for my year, it's steady state at ~30mph), but the idle test is what always proved just a little tricky. I've found that (at least for my car) I can never pass idle at 13:1 or higher afr, the engine stumbles a bit and the hydrocarbons go through the roof. I always pass right through at 12.3:1 to 12.5:1 idle afr, and that's where I keep it all the time, it seems to like idling that rich.

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