Thread: 5 Gas/Smog failure - High HC's at idle ONLY - 2g GSX

So I have to make my new project GSX pass smog by the end of April. I have had all major operational issues resolved for several weeks now, except our favorite - emissions. I used a 5 gas analyzer at school today to see how the car's emissions sits, and then actually smog tested it at the school's training station. Anyways, needless to say the car failed the smog test. It passes perfectly at 2500 rpm, and when i tested with the 5 gas, it pretty much runs clean at anything above idle.

Basically it fails the idle test only because of Hydrocarbons (HC's). Its unusual though...When I was 5 gassing it before the cat converter warmed up HC's were obviously not being burned up at all yet so it was reading like 550 HC, and when the cat was decently warm HC's weren't staying consistent. Sometimes it would be great - like around 30 or 40, but other times would go up as high as 150. When I did the smog test on it, it passed the 2500 rpm test as expected, but failed the idle test. After failing, the smog test program said that there are 3 pre-conditions to try when we test it again. Unfortunately, I ran outta time in class so I wont be able to test again with preconditions until Monday. One of the preconditions was to run the car at 2500 rpm for 3 minutes just prior to testing - obviously to heat up the cat.

Just wondering if any of you have suggestions or ideas for me. Personally im thinking its the catalytic converter or possibly slightly retarded timing. I did not check out my timing today but I will on Monday. I know spec is 5* BDC +/- 2*. Idle speed is within spec (750 +/- 50), and mine lingers around 770 - 780. No DTC's at all, none pending, all testable actuators/solenoids are functioning properly.

The GSX does have 3 inch exhaust downpipe back, including a high flow 3 inch cat. So my first suspicion was that the cat doesn't do a sufficient job...but at the same time, the previous owner showed me a printout of the last smog test he had done (in '05) with the 3 inch exhaust and cat on, and it passed. I think the failing point for HC is in the ball park of 100 (correct me if im wrong please). Maybe if i cleaned the fuel system (vaccuum injected cleaner thru intake just to clean out a bit, and then add to tank solution for during testing) i can get it to run hot enough to burn out some of those HC's?? Since awd cant be accurately tested for NOx (engine must be under load), technically i could just get the car running hot for the test so it could pass. But I'd also like to make the car run efficiently at the same time. The engine is running efficiently as CO2 indicates at about 14% ball park no matter if its idling or at 2500rpm. O2 never exceeds 1.3%. CO is always 0.


Performance Mod info:
3 inch exhaust down pipe back
3 inch hi flow cat converter
Apex'i Intercooler and piping
1g blow off valve - recirculated back to intake
K & N FIPK
NGK Iridium spark plugs


Thanks for your input.

Put a stock paper filter and air intake on it

Originally Posted by OldDirtyNoSeven

Put a stock paper filter and air intake on it

i take it you're thinking that the engine sucked in some of the filtration oil K & N uses on their filters?

ok well i am trying not to pay out the a$$ just to pass smog, so i dont wanna buy the stock air box and all that (cuz i dont have it). I think i need that part of the timing cover that covers the cam gears for smog though(???), and if thats the case then i'll need to go buy one of those and the bolts for it :x

anyways, since i can test my car at school for free i figured i'd do some small experimenting and see what will actually help me pass. im trying to be resourceful, as the budget has grown tight right now. So I did a fuel system cleaning at my work the other day - directly thru a vacuum line to engine, plus the additive into the gas tank. And while i was burning sh!t out using the vacuum injected chemical - i burned out tons of blue smoke, aka oil that was sitting in the exhaust from when the old owner blew the head gasket. burned out a ton of it. So that oil was what helped put out the high HC's as well as probably severely damaged my cat's functioning ability. oh and i was also finally able to service all gear boxes :D

Then today I spent about 2 hours testing it different ways. And that fuel cleaning really helped out a lot. just during the first test of the day, when the car had just barely reached operating temp, the HC's were way lower than last week. Anyways, I figured out that my cat is a biotch to heat up, and thats whats killin me. I tried the pre-condition that says to rev at 2500 rpm for 3 minutes before testing, and it would've passed. And guess what. At 2500, this car of mine puts out 0 HC, the highest out of about 15 tests today at 2500 was only 8 HC. Then the real test. Dropping it to idle after 2500. Whenever the cat wasn't sufficiently heated by the precondition, I would spike to almost 180 HC and then drop down. But when the cat was hot, the highest spike was 60 HC, and it would drop all the way down to about 15 within 30 seconds. So my car will pass smog emissions test, IF I can do that precondition and get that cat burning. Oh and all day long my A/F lambda was at 1.00 +/- .01 so perfect ratio. my timing is right on also. 02 sensors are working properly. It seems to me its the cat got worn out by all that oil going thru it, and sitting in it for over a year.

Only problem is that one of my instructors said that you cannot ask a smog tech to do a preconditioning until it fails the first test, because after the first fail, precondition options will come up on screen. So, basically my car will fail the first test, then on the free retest i do the precondition ---- BUT, if things dont align like they did most of the time they did today, I will have just paid for nothing but 2 failures.

Any help would be awesome.

Originally Posted by EclipseParadise

ok well i am trying not to pay out the a$$ just to pass smog, so i dont wanna buy the stock air box and all that (cuz i dont have it). I think i need that part of the timing cover that covers the cam gears for smog though(???), and if thats the case then i'll need to go buy one of those and the bolts for it :x

anyways, since i can test my car at school for free i figured i'd do some small experimenting and see what will actually help me pass. im trying to be resourceful, as the budget has grown tight right now. So I did a fuel system cleaning at my work the other day - directly thru a vacuum line to engine, plus the additive into the gas tank. And while i was burning sh!t out using the vacuum injected chemical - i burned out tons of blue smoke, aka oil that was sitting in the exhaust from when the old owner blew the head gasket. burned out a ton of it. So that oil was what helped put out the high HC's as well as probably severely damaged my cat's functioning ability. oh and i was also finally able to service all gear boxes :D

Then today I spent about 2 hours testing it different ways. And that fuel cleaning really helped out a lot. just during the first test of the day, when the car had just barely reached operating temp, the HC's were way lower than last week. Anyways, I figured out that my cat is a biotch to heat up, and thats whats killin me. I tried the pre-condition that says to rev at 2500 rpm for 3 minutes before testing, and it would've passed. And guess what. At 2500, this car of mine puts out 0 HC, the highest out of about 15 tests today at 2500 was only 8 HC. Then the real test. Dropping it to idle after 2500. Whenever the cat wasn't sufficiently heated by the precondition, I would spike to almost 180 HC and then drop down. But when the cat was hot, the highest spike was 60 HC, and it would drop all the way down to about 15 within 30 seconds. So my car will pass smog emissions test, IF I can do that precondition and get that cat burning. Oh and all day long my A/F lambda was at 1.00 +/- .01 so perfect ratio. my timing is right on also. 02 sensors are working properly. It seems to me its the cat got worn out by all that oil going thru it, and sitting in it for over a year.

Only problem is that one of my instructors said that you cannot ask a smog tech to do a preconditioning until it fails the first test, because after the first fail, precondition options will come up on screen. So, basically my car will fail the first test, then on the free retest i do the precondition ---- BUT, if things dont align like they did most of the time they did today, I will have just paid for nothing but 2 failures.

Any help would be awesome.

ok let me chime in for you. the timing cover will not fail you for visual so dont stress off of that. ok our cars like to be a little rich from factory. so my perfectly stock gst doing a two speed idle test will fail, without preconditioning at idle. 2500 no problem because it gets warmed up. every 4g63 that has been smogged including dsmguy142's car at two speed idle at my shop, failed the first try. The good thing about A TWO SPEED IDLE on a awd is that it doesnt go under load. so when the machine fails it, it actually tells the technician to precondition the cat and do the test right after while its still in the smog thats why most people dont ever know they failed the first try. Im not sure what machine you were using at your school or if you were just using 5 gas readings and not in the actual smog mode, but after the failure of the snifer it gives you a preconditioning period for 90 seconds and then tells you to hold 2500rpm then idle. This is on a ESP machine that i used at my school and at my work. so you dont "have" to ask the tech. and he wont fail you if you do.

I've got an extra timing cover. You can have it. No bolts though. you'll have to find those.

come to my shop with a dsm and i dont know you, ill fail you on the spot! i know its modded

rofl

thanks Jon, I'll keep that in mind and I'll PM you when I figure out for sure if I need it or not.

Originally Posted by george536

come to my shop with a dsm and i dont know you, ill fail you on the spot! i know its modded

rofl

lol just for that im coming to your shop...

really though thanks for the info George. And at my school I was using both a 5 gas analyzer and an actual smog station machine setup...just separate times. mostly used the real time 5 gas analyzer though. It was more useful for figuring out whats going on.

Does any one have any smog shop suggestions for the Sacramento area? Im not asking for a freebie 'clean pipe pass' (which is a federal crime), but just for an honest test only center. The 2 shops I went to with my last eclipse were the types of places that just try to squeeze every dollar outta you for retests.