ST Civic - Emissions

[Britt Dollmeyer]

My '90 Civic Si recently flunked emissions here in Arizona. Specifically the NOx portion of the test.
I'm posting here because of the plethora of ST Civics in SC & because of your experiences with a state serious about emissions.

According to the Inspection Station Literature, NOX failures are attributed to the following:
1. Malfunctioning EGR system
2. Abnormal Engine operating temperature
3. Air mangement system malfunction
4. Catalytic Converter efficiency
5. Over advanced off-idle timing

I have a feeling that the problem is due to the newly reflashed ECU from Redshift. I went through emissions last time with flying colors with the stock ECU.
I have gone through 2 tests now and the original readings were:

HC in grams/mile - .40 with 1.00 being allowable -- PASS
CO in grams/mile - 6.65 with 12 being allowable -- PASS
NOx in grams/mile - 2.54 with 2.50 being allowable -- FAIL

I really didn't think there was a problem with any of the emissions related components, so for the retest I only reset the timing back to the factory spec of 18 degrees BTDC(it was over-advanced), installed a new Distributor Cap/Rotor and spark plugs.
The retest readings were worse:

HC - .62 with 1.00 being allowable -- PASS
CO - 8.18 with 12 being allowable -- PASS
NOx - 2.78 with 2.50 being allowable -- FAIL

Does anyone have any success with particular timing settings, etc...with the reflashed ECU's?
Will I need to get a backup stock ECU?
Am I barking up the wrong tree?

I don't want to take the car to an actual repair facility & spend money only to learn that it won't pass the test with the reflashed ECU.

I'd be interested in hearing any ideas/experiences any of you may have had.

Thanks,

Britt Dollmeyer

[Steve Ekstrand]

Hey Britt! I was wondering how it was going for you in AZland. We were hoping to see you in SD next week.


How fresh is your converter?

NOx is the product of complete combustion. Based on your numbers you're probably running pretty healthy for power. If your converter is reasonably fresh, you're probably going to need to find a stock ECU. I just keep a spare stock box (one I had that isn't easily chippable). But on a socketed ECU, it might be helpful to see if a Honda tuner can send you an EPROM with the stock ECU flash. Pop in the chip and you'll smog easily.

You are so close though.... Any of those smog test additives you see at PepBoys and such work for NOx? Also.... longshot... I wonder if a higher octane fuel than you're using now might lower NOx just slightly. You have room on the unspent fuel side. Passing emissions is a compromise now that NOx is measured. It used to be easy to pass smog, tune up, heat up, lean out, bang you pass. Now all those things can raise your NOx.

[Jonathan Lugod]

Britt, I helped out the AllStar Team with their higher NoX levels as well. Turns out it had to do with using the reflash and the relocation of the o2 sensor.

1) Is the Cat fresh? Still 20 years old (replace it)...
2) The Redshift Chip leans out fuel mixture and advances timing. Your 15 mph test will pass but 25 will fail.
3) What header do you have? The Redshift Chip was designed for the o2 sensor to still be in the stock location (right off the header in the engine bay) and not down by the cat. That location was meant for OBD1/OBD2 cars using heated o2 sensors. If the o2 sensor is further back, the readings will be compromised and a different output for fuel will be used.

[Britt Dollmeyer]

Hey Steve & Jonathan,
The CAT is the original. I have a Magnaflow Direct Fit ready though.
I always use the highest octane pump fuel.. 91 here in AZ.
The header is a DC sports with the O2 sensor down by the CAT.
Do you think the O2 location is still a problem with the stock ECU?

[Steve Ekstrand]

OT-

My header builder like the D series O2 bung up on one of the primary tubes. Is that a good place? Only reads one cylinder. Will the stock wiring reach? And what is legal for ST, does it matter?

[Mike Shin]

Hey Steve & Jonathan,
The CAT is the original. I have a Magnaflow Direct Fit ready though.
I always use the highest octane pump fuel.. 91 here in AZ.
The header is a DC sports with the O2 sensor down by the CAT.
Do you think the O2 location is still a problem with the stock ECU?

Swap that OE cat out, it's close to, or past it's life expectancy.

Like Jonathan mentioned, the OBD0 o2 sensor being placed there may be affecting the readings since it's not an OBD1-2 heated sensor that is meant to be read further downstream.

And if you've got a stock ecu throw that back in.

[Steve Ekstrand]

The converter is a pretty easy swap out if you have the direct fit. Amazing what a new fresh cat nice and hot when tested can do for smog tests in these cars.

But yeah, I've always heard just what Jon said that the cars won't pass the higher speed tests with the Redshift chip.

[Jonathan Lugod]

OT-

My header builder like the D series O2 bung up on one of the primary tubes. Is that a good place? Only reads one cylinder. Will the stock wiring reach? And what is legal for ST, does it matter?

Steve, you are theoretically okay since you have a custom tune set the way the car is setup. For ST, the emission equipment needs to be in working order so the car runs properly as it came stock (pass emissions).

Britt, If you plan to swap out ecu's you MIGHT pass with the o2 sensor down stream but the readings will most likely be border line passing. I just had my exhaust guy weld up a bung where stock location would be.

[Thomas Smith]

OT-

My header builder like the D series O2 bung up on one of the primary tubes. Is that a good place? Only reads one cylinder. Will the stock wiring reach? And what is legal for ST, does it matter?

Older DC Sport D Series headers have the O2 Sensor on one of the primary tubes which is also the stock location. I think you only have to lengthen the wiring if the sensor is located after the collector. My 91 Civic has an old DC header I bought on Ebay and runs fine with the sensor there whether with the stock or Redshift chipped ECU. BTW, my former STS Civic is now a gutted rallycross dirt warrior....

[Britt Dollmeyer]

Well I guess I'd better get the new CAT in & have a fitting welded on the #4 primary.
In the meantime...anybody have a stock ECU laying around? Made some calls here but haven't found one yet.
FWIW...$836.00 from Honda

Thanks for all the input & if there's more...keep it coming.

[Steve Ekstrand]

At any given time there are usually 20 listed on ePay.

[Steve Ekstrand]

I've never tried my stock ECU. I assume its good. But I could send it to you can't find a cheap one on Ebay or Craiglist.

[Lily Liu]

Well I guess I'd better get the new CAT in & have a fitting welded on the #4 primary.
In the meantime...anybody have a stock ECU laying around? Made some calls here but haven't found one yet.
FWIW...$836.00 from Honda

Thanks for all the input & if there's more...keep it coming.

Do you get free retest if the car fails smog? We have a 30-day free retest at some locations in California; not sure how it works in AZ.

In the interest of time, you could take it to a test center with the new cat while you're looking for a stock ECU. If it passes, wonderful. If not, you have 30 days from then to find a stock ECU.

[Britt Dollmeyer]

I've never tried my stock ECU. I assume its good. But I could send it to you can't find a cheap one on Ebay or Craiglist.

Thanks for the offer Steve. I'll look on e-bay.

Do you get free retest if the car fails smog? We have a 30-day free retest at some locations in California; not sure how it works in AZ.

In the interest of time, you could take it to a test center with the new cat while you're looking for a stock ECU. If it passes, wonderful. If not, you have 30 days from then to find a stock ECU.

We do get a free retest within 60 days, but I just burned that up this morning.
$28 bucks for the new test & a whopping $31 for tags good for 2 years.

[Lily Liu]

We do get a free retest within 60 days, but I just burned that up this morning.
$28 bucks for the new test & a whopping $31 for tags good for 2 years.

That's cheap.. Lucky! If I send my car to you, will you smog it and register it for me in AZ? J/k!

[Mike Shin]

check http://www.Hondamarketplace.com Usually someone will have a 90-91 PM6 Ecu for sale much much cheaper than what the dealer is asking.

[Britt Dollmeyer]

I passed emissions today. I made one change at a time, so it took awhile to pass.
FWIW I'll go over what I did and the readings.

See the first post for the first 2 test readings.
For all the subsequent tests I left the timing at 18 degrees BTDC.

Test 3: Stock ECU
HC (grams/mile) - .38 with 1.00 being allowable - Pass
CO (grams/mile) - 4.88 with 12 being allowable - Pass
NOx (grams/mile) - 2.52 with 2.50 being allowable - FAIL

Test 4: Stock ECU and Stock Exhaust manifold with O2 sensor in the correct location
HC (grams/mile) - .33 with 1.00 being allowable - Pass
CO (grams/mile - 4.25 with 12 being allowable - Pass
NOx (grams/mile - 2.51 with 2.50 being allowable - FAIL

Test 5: New Magnaflow Direct Fit Hi Flow Cat(bolt in type)
HC (grams/mile) - .12 with 1.00 being allowable - Pass(big time)
CO (grams/mile) - 1.95 with 12 being allowable - Pass(big time)
NOx(grams/mile) - 1.19 with 2.50 being allowable - PASS(WOOO HOOO)

So, the new CAT was the big difference.

THANKS FOR ALL THE GREAT ADVICE.
BTW... rain again at the tour! Only the 1st run was dry this time(except for Ken) as I understand. I'll try to make it next year if the economy is friendlier to us Homebuilders.
Thanks again.

[Steve Ekstrand]

Wow!

That new cat really cleaned things up. I'd heard that on these cars.

Pretty funny how the lawmakers want you to prove your cat is damaged and don't want them changed out. Yet, look at what an improvement a replacement cat can make.

[Michael Smith]

Whew. Emissions can be a headache.
The past 2x for 2 of the cars I have done Pre-Tests.
They cost $20 and the results do not get sent to Sacramento. If it passes, you can have the car smogged officially with it still on the roller(s).
$20 is worth taking the risk of having your car labeled as a Gross Polluter (in California).
Something to think about for older cars.