Emissions FAILED!!!!

[silvermelon19]

ok well i took my truck to emissions today and found out that it didnt pass!!!! i was shocked. yes its a 93 but its in real good shape for its year. anyways the paper said that the Oxides of Nitrogen is over the state limit. So it must be the exhuast right????? any ideal what this is????? i got a flowmaster catback on if that matters any, anyways i have to go and get it checked out and i guess fix it before my deadline.

 

[V8BoatBuilder]

Could be your catalytic conveter is failing.

Here's what I would do. Make sure the vehicle is all tuned up: plugs, wires, O2 sensor, egr, pcv. If they're recent, don't replace them, but if they're old, now's the time.

Run a can of "Seafoam" through the brake booster hose.

Get one of those "gauranteed to pass emissions" gas treatments, and use it. Make sure you truck is nice and warm, and then go for your re-test.

 

[Glacier991]

Good advice. (except for the Seafoam part... on which I have no experience and nothing to base a positive or negative comment on so express no opinion). I too fear for your CAT.. It has probably given good service......

If you have the ability to do so, check your timing. (not like you can easily adjust it, but may be a clue).

 

[V8BoatBuilder]

My first vehicle was a 1991 Peugeot that my dad drove as a work vehicle untill it barely ran. He said, you can have it for free, if you fix it. Among problems such as a busted waterpump and failing timing belt, it too did not pass emssison for excess NOx.

I ended up getting a used catalytic converter from a parts vehicle. Technically that's illegal for, IMO, silly legal reasons, but it was the trick to getting the car to pass strict MA emissions.

One way to "sort-of" test the catalytic converter is with a high temperature thermometer (2000 deg F).
1) Get the truck nice and hot with a long drive. Keep it running. APPLY THE E-BRAKE, CHOCK THE WHEELS.
2) Put on some good gloves and long sleeves, and get under the truck. Measure the pipe temperature before and after the cat. If the cat is working, then the temperature BEHIND it will be signficantly higher tha the before temp.
3) If you get an increase, then go ahead with the snake-oil and the re-test. If not, then investigate replacing the cat.

What killed the Peugeot's cat was a rich-running engine, dumping unburned fuel into the exhaust. So if you do decide to replace the cat, make sure your engine won't kill the new one.

 

[JGAMBLE]

alrighty, my cat's been fixed for a couple years now. I've been looking for a hi performance replacement. After all if I'm gonna go cat-back, what about the cat and forward. Still looking for headers too, but who makes a good cat for these things?

 

[MrShorty]

My 2 cents worth:

Isn't high NOx a result of overly high combustion temperatures? That's what I've heard. So, what causes high combustion temperatures? The same things that cause these engines to ping (which is quite frequent. Does your engine ping?): carbon buildup in the cylinders and running lean. Run a search for ping on the early 4.0 OHV and try some of the things that come up.

The purpose of the EGR system (many '93's have an EGR system) is to lower combustion temperatures. If you have any EGR system, check it carefully to make sure it's working correctly.

Have you checked with the comptuer to see if it can see anything? NOt sure that it will, but it only takes a few minutes to check.

 

[silvermelon19]

it does make a noise of some what and some one told me it was the vavles rattling so i started using plus gas and a bottle of octane booster everytime i fill up. Could that be it?????? maybe its the high amount of octane im using????

 

[V8BoatBuilder]

it does make a noise of some what and some one told me it was the vavles rattling so i started using plus gas and a bottle of octane booster everytime i fill up. Could that be it?????? maybe its the high amount of octane im using????

Valve tick is not related to the gas octane used. In fact, running a higher octane than 87 will cause extra carbon buildup in your cylinders.

 

[SoBeLover]

My brother took my truck for emissions inspection on Wednesday and it passed. All he did was warm it up for a while. All my emission levels were under state limits

 

[Eneurb]

Is it an EGR or non-EGR system???

 

[MazdaGreg]

NoX is an indicator of High Combustion temperatures, as said in a previous post. Catalytic Converter will take care of some of this for you, but if your Cat was bad, your Hydrocarbons, or HC's would be way up there. Couple hundred ppm's at least. if those are low, i would look elsewhere. running lean would do this, in the case of a Vacuum leak, but most likely if it was enough of a leak, your o2's would pick it up. If it is an EGR Truck, i'd start there. My Navajo is the High Altitude model federal emission, so it does not have EGR. If that was happening to mine, i'd check for any codes stored in the computer and go from there. if none, i'd start looking for a vacuum leak. Also, since they are such a problem, the Mass Air Flow. I swear, you look at them funny and they get dirty.

Good Luck.