This thread was saved without dates. "Around Sep 2004" is estimated from neighbouring threads.
Yea, that sucks. I went to have my car tested (E-check in ohio) and turns out, i failed. i have JUST under a month to fix it. MY NOx (nitrogen Oxide)gasses were too high. My Hydrocarbons were up there, but at a passing level. I read that excessive NOx gasses are caused by increased combustion chamber temperatures...so, who's had this problem/knows how to fix it. hey, any help is appreciated!!!!
was this at the idle or high rpm test.. also wouldnt hurt to throw some injector cleaner, a few gallons of high octane gas wouldnt hurt either..
i only run 93 octane...and it was at 25 mph in 3rd gear ( i could hear the shifts, thats how i know in third, and the screen has a 25 mph scale-a-mabob on it!) injector cleaner..noted!
holy crap, look what i found!! NOx (http://www.gatewaycleanair.com/mechanic/air4_3/nox.htm)
Yeah I would tell you to check the function of the EGR valve first, by pushing up on the underside of the valve to make sure it moves, and checking the vacuum hose coming out the top of the valve for cracks and leaks.
Then pull the ECU codes, see if anything comes up there, and possibly replace the cat, although unless Ohio tests are really strict you should be able to pass emissions even if the cat isn't working. Most cats that are more than 5 years old or so aren't doing anything anymore, I'm pretty sure mine's not (I get that sulfur smell once inawhile when sitting at a light after a long period at speed), and my car passes NC emissions testing with flying colors every year. (Knock on wood.)
That sulphur smell is actually a good indication your catalytic is STILL working.
A sudden rich/lean condition makes the rotten eggy smell.
When your mix is stoich or close, the convertor converts it into ... uhmm ... too early for chem ... sulphuric oxide?
When you go from lean/rich, like idling for long periods, chugging up a hill ... the converter doesn't really work with rich conditions. It can't properly convert the sulphur, so it gets smelly.
I'm not explaining myself properly ... but yeah, too many people get catalytic converters replaced when it's actually their motor's fault.
But yeah, start with the EGR, and check vacuum hoses with a torch ...
...convertor is 6 months old...IF ITS BAD, :guns: but ill look over the line from the EGR..on the V6..the EGR is located on the passenger side closer to the firewall..its the metal mushroom looking thing right? that thing in the pic..its gray...
http://memimage.cardomain.com/member_images/3/web/531000-531999/531655_34.jpg
NOT whats circled..but the thing to the left (that vac line coming from the egr, to the switch-mabob is busted on mine..could it be that?!
sure ...
blown vacuum line = air leak
air leak in an NA car = unmetered air
which in turn = lean condition
which causes your combustion temperatures to soar
which, you guessed it,
causes high NOX levels
That sulphur smell is actually a good indication your catalytic is STILL working.
A sudden rich/lean condition makes the rotten eggy smell.
When your mix is stoich or close, the convertor converts it into ... uhmm ... too early for chem ... sulphuric oxide?
When you go from lean/rich, like idling for long periods, chugging up a hill ... the converter doesn't really work with rich conditions. It can't properly convert the sulphur, so it gets smelly.
I'm not explaining myself properly ... but yeah, too many people get catalytic converters replaced when it's actually their motor's fault.
But yeah, start with the EGR, and check vacuum hoses with a torch ...
It is either Sulphuric oxide, or Sulphure dioxide...I forget which...8)
Ok, NOx fail, first check your egr operation. You need to check to see if you have vacuum to the valve and that it is lifting it up and able to hold vacuum. Also, you can check to see if the internal part between the exhaust side and the intake isn't plugged up with carbon by using a hand held vacuum pump and connecting it to the egr valve and apply some vacuum to it. See if the valve moves, if it does, the engine should start to die or stall completly. If it doesn't, then the valve has a leaky diaphram, or more likely the exhaust to intake path is blocked with carbon and needs to be cleaned out. Another thing to check is to be sure your timing is set correctly, if its over advanced, the NOx will also be higher. And the cat should last as long as the vehicle if properly maintained (Well. at least thats what the manufacturer claims.) Ussually what kills that cat is an improper running engine (Worn engine causeing oil burn off in the exhaust), leaded fuel. Another cause for higher levels of NOx is if the car is overheating on there machine. I had a camaro that failed because I didn't top off the water first and it ran hot and failed NOx. Topped off the water and brought it back to the same shop the next day and it passed no problems. It could be nothing more than the Thermistat staying close. Just some things to check, let us know how it goes.
Edit: Oh, one more thing, if the egr valve checks good when you use the vacuum pump directly on the valve, check to see if you are getting vaccum to and from the solinoid that the egr valve is connected to. If there is no vacuum before the solonoid then make sure all the lines are in good shape and connected corectly. If the hose are ok and still no vacuum, then its probably that thermistatic vacuum tree thingy at the front of the engine. It cuts off vacuum to the egr till the engine reaches operating temperature. Ok, I will stop for now.
It cuts off vacuum to the egr till the engine reaches operating temperature. Ok, I will stop for now.
maybe that explains my horrible idle when cold?!
EDIT: well..i've narrowed it down to a few things (lol, a few). EGR valve, Camshaft timing (ie timing belt & tensioner), or a bad coolant mix. ok i doubt its the coolant mix, as its pretty close to 50/50. EGR valve, probably it, but it sux at $93.88!! timing setup (tensioner, belt, water pump, gasket...TIME) and thats still less than $93.88!! but im leaning towards EGR. regardless, im doing timing sooner (now if its not EGR) or later (spring). funny thing is last year when i tested, they didnt do NOx gasses. now they do, and thats what got me! but all the numbers have improved...207,650 miles!