Failed NJ Inspection(emissions)

[TheProdigy001]

hello,

i have a 1988 gmc s-15 jimmy 4x4 4.3L engine.
i had just failed for emissions. my reading was

idle-
HC ppm reading 665 ---allowed 220
co% reading 1.88 --- allowed 1.20


high idle-
HC ppm reading 260 ---allowed 220
co% reading 1.35 --- allowed 1.20


what could be causing this?

i am checking out the truck now i will post any findings

 

[SuperEd73]

Well it's a pre-OBDII setup but it is still computer controlled. Could really be a wide variety of issues since everything is high. Has it been tuned up lately? Mileage really high? Malfunctioning cats? Check Engine Light on recently? Fuel Injectors dumping too much fuel?

I'd start with the basics first. make sure everything under hood looks to be in good shape, i.e. no vacuum leaks, worn vacuum lines, ignition timing is correct, new spark plugs/wires/dist. cap.

From there, make sure no trouble codes are showing up in the engine computer's memory. Its from 1988 so it's not as advanced as today's engine management systems but that engine still does use a computerized management system.

Ed B.

 

[getnpsi]

Does NJ test for nox? if they are both high you could just have a bad cat. I would start with the basics like a misfire letting more unburned carbon thru. Is your thermostat oem temp? Do you have larger tires on that 4x4 and did not regear? Putting around at lower rpms pollutes more as you are relying on the o2 sensor to get the mixture just right. More rpm tend to clean up as there's more spark advance for a better burn.

 

[TheProdigy001]

here is what i found so far.

my air filter is pretty dirty. the 3 spark plugs i looked at are worn. and my pcv valve has thick goo on it and in it.

could any of them be the problem.

 

[Trav]

Was the vehicle up to operating temp at test time?
HC is simply unburned fuel/hydrocarbons being measured at the tail pipe.
CO is more of an indicator of the mixture (rich/lean) being burned.
This is in the simplest terms it is a lot more complex than that but you get the idea.

Check the air filter,PCV,ect and try a new set of plugs.
Get the motor up to operating temp with a 20 mi run on the freeway and retest.

Edit i just saw you latest post.Yes all those things can be the cause.High HC is bad for the cat so it would be benificial to keep on top of this engine.

 

[c3po]

Originally Posted By: TheProdigy001
and my pcv valve has thick goo on it and in it.


You may need to clean up your breather baffles, since 3 spark plugs were worn you may not have been burning the fuel well and this could lead to the higher HC number.

You may need to pop your valve cover off to clean up the breather baffle.

I believe this was the car you did arx on that was blowing blue smoke.

 

[dailydriver]

Originally Posted By: TheProdigy001
here is what i found so far.

my air filter is pretty dirty. the 3 spark plugs i looked at are worn. and my pcv valve has thick goo on it and in it.

could any of them be the problem.


YES, these three items alone could be what caused you to fail.
But I would keep checking even further for more culprits, as it could only help your fuel mileage and performance (not to mention keeping our air cleaner

).

Trav makes a GREAT suggestion above, as to running on the highway up to full operating temps before pulling into the station.
Hopefully you'll have an appointment and they don't make you wait long enough for the engine oil/coolant/block to cool down.

BTW; Just curious, did they put you on the rollers for this test, or did they just idle/run the engine unloaded??

 

[FL_Rob]

A total tune up/cleanup its easy on this vehicle also check the egr ,follow SupereEd73s' advice on vac leaks,then give it the Italian tune up.

 

[2oldtommy]

After all the suggestion already said, try running a bottle of Techron complete fuel system cleaner thru one tank of gas. I had a 78 Lemans with a 305 small block Chev. that would clean up to pass emissions check with just this one remedy. Try it and see.FWIW-- Oldtommy

 

[Chris142]

Replace the plugs, wires, air filter and change the oil and filter.

 

[eljefino]

^ +1 fresh oil is a "sponge" for nasty stuff.

 

[Scdevon]

Your Cat(s) is probably tired. You could run your fuel tank very low and add a very large amount of "Heet" (alcohol) to the fuel tank just prior to the emissions test so that the engine is running on a high percentage of alcohol. Ditto on the fresh oil and filter.

Creating a small vacuum leak by disconnecting a vacuum line at the intake manifold helps, too.

 

[getnpsi]

Originally Posted By: Scdevon
Your Cat(s) is probably tired. You could run your fuel tank very low and add a very large amount of "Heet" (alcohol) to the fuel tank just prior to the emissions test so that the engine is running on a high percentage of alcohol. Ditto on the fresh oil and filter.

Creating a small vacuum leak by disconnecting a vacuum line at the intake manifold helps, too.


If the o2 sensor is doing it's job it will read a lean condition and add fuel with unneeded emission spikes trying to get it to stoich ratio. That can make a hunting idle and that's the worst thing to do at low RPM.

After the followup post I agree with the above posts. It sounds like the OP needs a full tuneup with removal of some easy stuff, and 2 family sized cans of carb cleaner.

 

[Scott_Tucker]

Is this a computer controlled carburetor?

 

[Scdevon]

Originally Posted By: Scott_Tucker
Is this a computer controlled carburetor?


Should be throttle body injection (AKA post nasal drip).

I have to disagree. Creating a small vacuum leak is just what the Doctor ordered for an idle emissions test. Most O2 sensors out there are tired and even if its a healthy sensor a vacuum leak will take the PCM outside of its short term fuel trim parameters. Eventually, it it will set a MIL light, but it will temporarily reduce the idle emissions.

I haven't lived in the People's Republic of New Jersey in 12 years. I don't know if they still perform an idle emissions test or a simulated road test emissions test.

 

[another Todd]

A very dirty air filter alone could cause it.

 

[Scott_Tucker]

Originally Posted By: another Todd
A very dirty air filter alone could cause it.


Only if its carbureted.

 

[TheProdigy001]

i still have not been to inspection do my my daughter recently being diagnosed with a life threatening illness.i have been in the hospital the whole time except for the last few days.now i need my truck inspected and in that time NJ changed to where i only need to pass emissions for inspection(effective aug 1 ,2010 .unless you failed for a mechanical defect before aug 1st then that will need to be fixed and reinspected.
what exactly does mechanical defects mean.

i failed for one tire had a little less tread then allowed.my horn was not working,and my one light did not work at the time.and emissions.would any of them be considered a mechanical defect.

 

[RacerE7773]

Sorry to hear about your daughter.

A lot of states are anal about mechanical defects, and some are not. The stuff you mentioned could be considered mechanical; the emissions is by itself.