Failed Smog (Help)

[Stigmata]

Hi I just failed my smog test today, here are my results, If you guys have advice what to change, replace, please type it here any advice is welcome

HCHydroCarbonsStandards: 0.80Mine: 1.64

COCarbon MonoxideStandards: 15.0Mine: 16.7

C02Carbon DioxideMine: 346.3

NOXMine: 10.40

[Kenrik]

Modified by Kenrik at 6:39 PM 8/16/2005

[InsanityInc]

What the heck is up with your readout? Could you post some units? Usually HC/NOx is in PPM and CO/CO2 is in %...

[Ubernoober]

God what a load. Don't buy high end racing fuel. What are we talking about here? Gasoline? Rocket fuel? I mean c'mon. Anecdotal evidence on an engine that has few similarities to yours will just cause you to waste your money.Take a look at your readings. Your HC suggests incomplete combustion either from running too rich, burning too much oil or having a bad or coked up cat. CO sounds rich also.240's are notorious for high NOx, but since there does not seem to be a standard for you I wouldn't worry.

As always, your greatest chances of passing are by doing a competent tuneup and making sure everything functions as Nissan designed it.

[Stigmata]

I'am runnning 93 Octane fuel? too high?, also I belive my catalic converter is fried, changing that as soon as possible, if I go back to 87 octane fuel and a new catalic converter will I pass?

[Kenrik]

240's run better with higher octane fuel... it even says in your manual to use high octane fuel.. most people I know can run midgrade without a noticeable difference in proformance. Those same people have also used normal unleaded and their cars would run really rough... I doubt running lower octante gas will help with your smog test.. Lower octane fuel is easier to burn.... Because of the high compression in the 240sx engines you can end up with detonation... which is not good!! http://www.misterfixit.com/deton.htm here is a good write up on it.. with all the info on why NOT to use 87 in your 240... "The octane rating of a given grade of gasoline is a measure of its detonation resistance. The higher the octane number, the better able the fuel is to resist detonation. Most engines in good condition will run fine on regular grade 87 octane fuel. But engines with high compression ratios (over 9:1), turbochargers, superchargers, or with accumulated carbon deposits in the combustion chamber may require 89 or higher octane fuel." As far as racing fuel... depends on your setup.. are you running turbo? what mods do you have in the car? Racing fuel might help! and When I say racing fuel I mean High octane fuel 93+.... Do a tune up on your car.. check your O2 sensor if it's bad it can screw up your emissions and make the car run rough.. plugs/wires.. Clean your MAF Clean your AIV if you have one! if the AIV is dirty it can mess up your emissions and make your car run rough also.. if you have a bad Cat then you need to get a new one... and ubernoober learn some manners..

[VinceSez]

i was told to only use 91+ octane if your car was souped up with whatever... i just run on 89 octane =)

[Kenrik]

Well that's midgrade... as I said most 240 owners find midgrade runs fine... you do get more HP by using higher octane (if tuned right) http://www.sdsefi.com/techocta.htm <--- info on that... i'm saying don't use 87... My 1989 Nissan manual says use 91+ it's what the car was made to take..

[Stigmata]

All I have done is a Injen Intake, 3" Catback exhaust, AVI is not plugged into the intake (Does it have to be), Thats about it to performance mods, I was wondering if high heat on a car will help emissions, I can always get there on a hot engine, I'am changing my catalic converter today

[Stigmata]

Also my timing if F***ED up, will that cause emisions failure?

[Kenrik]

Almost anything that makes your car run like crap will cause emissions falure.. if the car is not burning the fuel the way it needs to then you will fail... So yeah.. if the AIV is not hooked upto the intake then it's not doing what it's supposed to do and you are just pumping exhaust into your engine compartment and that's NOT GOOD... Clean your AIV and hook it back upto the intake it's hooked up there for a reason... it's supposed to help the Cat to cut down on emissions! it sounds like your car needs a lot small stuff done to it.. lot's of small stuff makes a BIG difference... Good Luck!

[Stigmata]

Thank you everyone for advice :P

[sanioll]

you need to clean the carbon buildup in your engine.

Run seafoam through, see my signature.

[Stigmata]

Where can I buy seafoam

[VinceSez]

autozone, napa