failed emissions testing

[kylekinnamon1989]

i got a 91 ka24de. went to get emissions this morning and failed hydrocarbons. min is 1.00 grams per mile, i got 1.20carbon monoxide. min is 12.00 grams per mile, 8.01oxides of nitrogen. min is 2.50 grams per mile, 3.59what could i do to fix this? the guy said part of the reason could be because of a backfire, i did a timing advanced and after i did that i did get a little back fire, could that be the reason?

[kylekinnamon1989]

anyone?

[rioredstang]

I would get the timing set correctly. You need to make sure the engine is nice and hot when you go. I'm in TN so our emission test are a little different but, I don't cut the engine off in the lanes to keep the cat warmed up. I will even idle it up to 1500rpm before going in. Set the idle up a little 100-200rpm if you can. They don't check rpm here so the extra idle will clean them up some. A little alcohol in the gas will lower emissions. Make sure engine has proper tune up.

[kylekinnamon1989]

yeah, i hear about the alcohol in the gas tank, i actually bought a 32oz bottle, do you think it would be ok to pour a little bit into the brake booster line?

[rioredstang]

I don't think it would hurt anything, it will just help clean intake some. I would check all of the basic tune up specs, then set the idle a little higher.

[Klits562]

you failed in arizona? how? dont people on here always hail arizona as being a place of sanctuary from smog test?set your idle to factory specs, if your backfiring bad then your probably running rich, i had back fire on decel and still passed first try, with my aiv disconnected and consiquently i failed visual inspection.Do an oil change, fuel filter change, run some injector cleaner, new spark plugs i use ngk.

warm your catalytic converter real good because the warmer it is the better it works.Also if your cat is old get a new one. It will be around 200 bucks at a shop.also do you have any aftermarket parts headers intake or anything like that?

[kylekinnamon1989]

that might be one of the problems actually, i didnt let the cat warm up.. i live like 4 miles from the emissions testing place, i drove straight there and didnt even have to wait i line... ive done injector cleaner thru the gas tank and booster vacuum line, oil change, new spark plugs, and fuel filter is maybe a year old.. and i do have a cold air intake!

[Wc240]

dont change the idle speed. they check it in cali and az. theres a small window for variatioin pending on the car.deffinatly make sure its wrmed up.

just becouse the cats old, DONT get a new one. you didnt fail bad enough to even consider the cat.

[rogoman]

i got a 91 ka24de. went to get emissions this morning and failed hydrocarbons. min is 1.00 grams per mile, i got 1.20carbon monoxide. min is 12.00 grams per mile, 8.01oxides of nitrogen. min is 2.50 grams per mile, 3.59what could i do to fix this? the guy said part of the reason could be because of a backfire, i did a timing advanced and after i did that i did get a little back fire, could that be the reason?

Several possibilities:

High CO- Make sure to use an OEM thermostat. If the coolant temperature is too low, the temperature sensor will indicate to the ECU that the motor is cold thereby making the ECU run a richer mixture.- Check the temperature sensor for the proper resistance values when the motor is cold and when the motor is hot. If the sensor is bad, it'll cause the ECU to run a richer mixture.- Leaking fuel injector(s).- Fuel pressure too high.- Bad CAT.- Incorrect ignition timing.

High NOx- EGR valve not working; the valve itself may be bad. Check the vacuum line running from the secondary BPT Valve to the EGR. That rubber line has a tendency to crack / melt. - Check the BPT valve.- Check all vacuum lines in the EGR assembly.- Bad CAT.

[Wc240]

^^^not the temp sensor or thermostat, HCs and CO would be alot higher and nox would be way lower.

leaking injector is possible, normally would be higher HCs tho.retarded timing would also yeild higher hcs and co and lower nox levels

[kylekinnamon1989]

failed again..i put a 32oz bottle of alcoho, fixed the timing, let the cat warm up, new spark plugs, and fix a vacuum line on the egr. hydrocarbons. min is 1.00 grams per mile, i got 0.59carbon monoxide. min is 12.00 grams per mile, 5.01oxides of nitrogen. min is 2.50 grams per mile, 3.35

i still failed on the oxides of nitrogen

[seang]

It looks like the alcohol helped the hydrocarbons, so that's good. I thought it was EGR that lowered NOx, and that's where you failed.

[kylekinnamon1989]

yeah i have no idea.. i guess the only thing i can think of now is to replace the cat?!

[Wc240]

alcohol burns faster and hotter than petrol. couses your elevated nox. with your current numbers, you cant diagnose it due to running the alcohol.

[rioredstang]

You need to find someone with a 5 gas analyzer and let them check and set timing. They can adjust the timing while watching the Nox. Sometimes I can create a vacuum leak to reduce HC levels. Also so they can set idle speed to upper limits.