The car has 90,000 miles
it is a 1995 GSR has only Injen Intake and Catback.Also highflow cat(2 yrs old).
I went to smog the car today, and drove on the freeway prior about 15-20 minutes. Changed the oil 100 miles ago(but I over filled just a slight bit)...
Today I went to smog but the car passed with flying colors minus the HC (PPM)
Which for CA law is allowed:
15 mph // Max Allowed= 90 // Measured: 190
25 mph // Max Allowed= 56 // Measured: 75

The smog guy said a new OE spec cat should fix that however the one I'm still in an enigma about is:

the NOx ...For 15 mph max allowed is 711...It measured in at 1480..
I only use 91..The timing is within spec (14).
Any ideas what I should do?
Should I seafoam to bring down the NOX?

Also what's allowed for timing..I'm at 14



Modified by SprocketRocket at 6:37 PM 8/11/2007

 

14 degrees timing is too retarded and that's what's causing you not to burn all the fuel. The extra fuel in the exhaust is making it too hot causing NOX. You may have other problems as well.

You're not giving us the O2 and CO so that's the best I can give you.

Cat converter is not the problem, unless running rich has destroyed it. They just love to sell you a new cat converter because it has a high margin.

 

Timing spec is probably 16+/-2, but check that on the sticker under the hood.

You have no O2! You're running rich. I'm not at home to look over my cheat sheets and see what else I can tell you. But with Hondas, you just do all the maintenance and they pass. Especially when it's just HCs (and I believe high HCs are what's causing your high NOX).

Test your O2 sensor with a multimeter. Change your ignition rotor, distributor cap, check the gap on your plugs, only use NGK or denso.

In the end you'll get better mileage and power.

 

How do I test the 02?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SprocketRocket &raquo;</TD></TR><TR><TD CLASS="quote">How do I test the 02? </TD></TR></TABLE>

Id like to know this as well.

 

buy new plugs and pull your ignition timing and youll pass. Your not burning the fuel at all. It almost looks like you are having a rich misfire. But your co2 levels are good. Your engine is running a little hot though, change your oil recently?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by rdssk8rcs1 &raquo;</TD></TR><TR><TD CLASS="quote">buy new plugs and pull your ignition timing and youll pass. Your not burning the fuel at all. It almost looks like you are having a rich misfire. But your co2 levels are good. Your engine is running a little hot though, change your oil recently? </TD></TR></TABLE>
The plugs are brand new, and the ignition is pulled back to the "CA" max. Jay J helped me on that.
The oil was changed recently and I think I may have over filled it just a tad bit. should I swap it out with like 10w30 instead of 5-30?

 

you can drill some holes in the exaust which will let more o2 in and it will lower the percentage of hc and nox and then weld them closed afterwards its an old school trick my emisions teacher told us about

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by got wide &raquo;</TD></TR><TR><TD CLASS="quote">you can drill some holes in the exaust which will let more o2 in and it will lower the percentage of hc and nox and then weld them closed afterwards its an old school trick my emisions teacher told us about </TD></TR></TABLE>
Won't I have an exhaust leak?

 

Dude,
how the F does high hc cause nox? the high HC (fuel) cools the cylinder down.if you have both high its usually the cat.Set your timing exact ,16 for your car.run some 10 dollar seafoam and buy a real cat.most aftermarket cats are only good for one smog anyways.Also homeboy should learn what your talking about before giving people advice.Also if your co2 is good don't worry about tune up parts your throwing your money away.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mrdeezy &raquo;</TD></TR><TR><TD CLASS="quote">Dude,
how the F does high hc cause nox? the high HC (fuel) cools the cylinder down.if you have both high its usually the cat.Set your timing exact ,16 for your car.run some 10 dollar seafoam and buy a real cat.most aftermarket cats are only good for one smog anyways.Also homeboy should learn what your talking about before giving people advice.Also if your co2 is good don't worry about tune up parts your throwing your money away.</TD></TR></TABLE>
So set timing to 16. Run Seafoam+ new Cat?

 

I would guess it has something to do with the oxygen sensors.

 

check your 02 to see if its switching, you can do this with a multimeter, your 02 should be a 3 or 4 wire. if u connect one end of it to the signal wire, and other to ground you should see the voltage switching from high to low very fast. i think thats the way to test it out.

 

You need an oscilloscope to test the 02 sensors correctly.A multimeter will not switch fast enough to be accurate or to check cross counts.Just buy a new 02 sensor, you only need one for that car.The o2 sensor would help with the accuracy of your c02 levels.C02 levels are efficiency you wanna be around high 14 low 15 for efficient combustion.Good Combustion = c02 which equals performance gas mileage and basically a good running engine.

 

my numbers were almost identical to yours....i changed my car and passed with flying colors...

 

High Nox is usually caused by clogged EGR system. Check your egr valve or passageways. Also, putting a cooler themostat might help.

I just failed smog.
My HC was at 9PPM. Very clean.. But NOX was at 1800PPM. I need to clean the EGR ports, unfortunately, on my car the EGR cleaning ports are welded shut.

Gary