Hi guys,

Last week, i tried to smog my 1997 maxima but it failed (I live in CA btw). Everything passed with flying colors except for the hydro-carbon emissions, which i failed by 6 points at 25 mphs. The smog guys said that I should change out my spark plugs, which I did, b/c I haven't changed them out in over 100K miles. I retested, but I failed again. My HC levels went down a few points, but it was still 3 points over (I am at 42 and the limit is at 39).

I installed a WS y-pipe around 4 years ago, and I barely passed ever since. But this year, I didn't pass. I made sure that the engine was nice and hot, and I even used CRC's 'Guaranteed to pass' stuff, and premium gas.

What should I do? Do I need to buy a new cat, or should I just re-install my old stock y-pipe (which has the pre-cats)? (most cats that are sold online are for non-CA emission standards, and those that are made for CA are really expensive) Or is there anyway I can run a little more lean, instead of rich. Or is there an easy way to burn more of the unburnt fuel? Cheap and easy is the best way to go for me.

Thanks!

 

do an oil change before the next test.

 

tune-up: air filter, fuel filter, oil change

PLUS

I don't remember the name, you'll find it at Autozone or Advanced Auto Parts, it's the stuff you put in your gas tank to thaw the ice on your fuel lines; use 2-3 bottles with a 1/4 of tank of PREMIUM gas

Any codes?

 

So I assume there aren't any codes? But if you haven't already cleaning out the TB/IACV may be worth a try. Generally if your main cat is hot enough (after a good highway run) testing with the aftermarket Y is no problem. But I remember reading cases were having the stock y-pipe reinstalled helped em pass smog in the past. So I guess it wouldn't hurt to put it back on before a re-test and before you explore the last resort of replacing the cat.

But geesh, that is ridiculous... what part of Cali are you located in? A 39 HC max seems pretty tough, here in the Bay it's 55. While on the topic, two weeks back I just passed smog four months late with a WS y-pipe and a high flow cat, measured 55 on the dot for HCs .

 

I'm in Riverside, CA.

Yeah, 39 seems really low, but that was the limit for 25 mph. At 15 mph, the limit is set for 55.

I was talking with some friends, and they suggested that I use 87 octane (regular) gas because i am running rich. They said that higher octane gas requires higher compression which means that it is a little harder for everything to burn. Is that right?

 

have you cleaned your MAF sensor?

 

High HC's means you are exhausting unburnt fuel... considering you changed plugs... may be coil packs... o2 sensors...

Also... are you auto or stick? If stick... tell the guy to run it in 2nd gear... high RPM's... hotter engine... a little higher NOx... but lower HC's.

 

I failed emissions and had hc, like was said before it is from unburnt fuel, if you changed your plugs, make sure your coil packs are firing. You should be able to pass with an aftermarket y pipe IF your cat is working, if the cat is shot then you will have high hc. If oil is dirty you can have high hc too. Hose from the valve cover needs to be connected to the intake if you have an aftermarket intake. Hi flow cats are basically garbage if you need to pass emissions. I found that out the hard way. Suspect the o2s if they haven't been changed in 50k miles or you get cel from them every once in awhile.

 

Sometimes it's just the simple things; check the vac line to the FPR, make sure it hasn't come off or split.

 

Heet, aka alchohol. all it does is a) burn cleaner than gas b) remove water from your fuel system

I would just go into the dollar store and buy some rubbing alchohol and pour the bottle in.

 

Thanks for all your help.

I put my stock Y-pipe back on and I passed smog.... barely. My HC are still high.

I want to put my aftermarket Y-pipe back on, because I can't put on one nut on the lower header around the fatter stock Y-pipe. I used a swivel, extended rachet and everything. (In fact, I think i messed up the threading a little while trying to get it on). So, now I have a non-air tight Y-pipe, which makes some noise when I gas it a little.

Either way, I'm still dreading the smog test two years from now... I think I'll try the rubbing alcohol method. (ratio is 1:3.5, gas:alcohol??) If I do this only a couple of times (ie for smog testing) it should be ok for my car?

 

I finally passed after I put my stock intake midpipe back on and changed my oil. The car did not just pass after I did that, it passed with flying colors. Sometimes dirty oil can cause high hc readings.