Failed NJ Inspection

I had the same problem. I advanced my timing and forgot to turn it back before I went through inspection, NOx was high like yours. I went around the block and turned the timing back to the stock setting and went back through with no problems. You could try and give that a shot! Good luck!

mkk50 said:

Ive searched through a lot of other posts, and couldn't find anything specific to my cause.
I have an aftermarket cai (bbk), bassani headers and x pipe, and flowmaster exhaust. The car has 2 cats on it still, but with the sniffer connected it pushed out almost 1673 NOx, where max allowed is 1088. I think that it has to deal with the car idling at around 850 to 900. Ive cleaned the egr valve, Throttle body, MAF and the IAC. Checked the vac and it was 19 psi, so im not sure what else to do. I think the car might have underdrive pullys, but i can't be sure. I just bought the car 2 weeks ago. Any help with reducing the NOx or lowering the idle would be nice

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NOx is a by product of Nitrogen, Oxygen, and Heat. Are your temps running high? If you still have the stock t-stat it may help to go to a 180. This may hurt your HC (or NMHC depending on what NJ tests for) readings though.

Wait, what was I thinking? First thing to do is pull the codes. Let the computer give you a clue as to what is wrong, it usually has a pretty good idea of what's going on with the motor.
Out of curiousity are the cats from bassani?

jason

if you want to keep NOx down and only want to keep it down for inspection rig up a system to inject water into your exhaust. Its how we do it at work with jet engines to keep everything fine and dandy so we dont get hit with fines. and also dont feel bad I never passed a nj inspection before

o2 sensors bad?

streetflossin said:

if you want to keep NOx down and only want to keep it down for inspection rig up a system to inject water into your exhaust. Its how we do it at work with jet engines to keep everything fine and dandy so we dont get hit with fines. and also dont feel bad I never passed a nj inspection before

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Would you suggest injecting at the head or post cats? How does the water remove NOx? I have never heard of this before and I am very curious.

thanks

well let me first by saying that water injection is a great way to reduce nox I have not personally every used it in a car before. now with that said lets talk about if i had to.
with water injection water in injected directly into the combustor through a modified injector, water reduces the temp in the combustor enough that the formation of nox is reduced. now mind you that setup would not work in a car engine so the theory is the same but the process altered. The best result would be right off the headers, but then your have water droplets running thru your exhaust system, and if it is a cheap system it will rust from the inside out, and then youll have a whole new emission problem. and also the water has to pretty pure for that too, so in theory it will work, but to actually get it working for this application will take alot of trial and error

I'm not sure if this has any validation to it, but my neighbor told me that they can't get accurate readings with the sniffer if it's raining outside. He said something with the rain, and humidity, or whatever causes them not to be able to use the machine. He was saying that they just put it in there and don't really do anything with it.

I don't know about this, but he went through with his old ass truck on a pouring rain day.....and it passed

streetflossin said:

well let me first by saying that water injection is a great way to reduce nox I have not personally every used it in a car before. now with that said lets talk about if i had to.
with water injection water in injected directly into the combustor through a modified injector, water reduces the temp in the combustor enough that the formation of nox is reduced. now mind you that setup would not work in a car engine so the theory is the same but the process altered. The best result would be right off the headers, but then your have water droplets running thru your exhaust system, and if it is a cheap system it will rust from the inside out, and then youll have a whole new emission problem. and also the water has to pretty pure for that too, so in theory it will work, but to actually get it working for this application will take alot of trial and error

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I have heard of water injection to delay detonation with boost, but not for decreasing NOx for emissions purposes. For it to have an affect on the the combustion temps though it would have to be injected prior to combustion. I can't see how injecting after combustion would reduce NOx, unless water droplets accumulate NOx like bong water .

grey5.0beast said:

o2 sensors bad?

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Interesting point but, O2's shouldn't affect NOx, unless they are really bad. I would think other symptoms would come up as well. Are you having driveability issues mkk50?

it would reduce nox by cooling down the exhaust gases, hotter gas = more nox

Cooling post combustion is not going to be as effective as cooling the combustion temps. Temps have already dropped a great deal by the time the exhaust gasses get past the exh valve. Not much benefit there.

I failed once before it was state run and I had a high idle. Lower it down to 650 and try again. IAC needs to be disconnected to do this. Idle screw is on throttle body where fuel pedal cable is hooked up

mkk50 said:

im thinking of replacing the cats, any1 have any other tips/ideas?

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I don't think cats would help NOx much, but it depends on the type of cats you put in.

mkk50 said:

if i back the screw out any further, the gas sticks badly, making the car undriveable

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Can you elaborate on this, it sounds odd.

For the low coolant light try cleaning the sensor in the overflow tank, they get dirty and send erratic signals.

mkk50 said:

When i back out the idle screw, something hangs up in the throttle linkage or the cruise control link, making the gas pedal extremely hard to push down at first. Once its down, its fine, unless i let back of the gas, then it sticks again. It basically makes me have to slam my foot on the gas while trying not to floor it.

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This sounds like a mechanical problem. I would suspect the linkage on the underside of the TB. Take some time and poke around while working the throttle plate around (with the engine shut off is fine).
I doubt that the pedal assy is the culprit, but anything is possible.

How to pass emissions testing:

1.) Make sure all the emissions gear the car was made with is present and connected up properly. That includes a working smog pump and cats.

2.) Make sure that you have fresh tune up with spark plugs, plug wires, cap, rotor, fuel & air filters. An oil & filter change is a good idea while you are at it.

3.) Dump the codes and see what the computer says is wrong…

Here's the link to dump the computer codes with only a jumper wire or paper clip and the check engine light, or test light or voltmeter. I’ve used it for years, and it works great.

See http://www.troublecodes.net/Ford/
OR
See http://www.mustangworks.com/articles/electronics/eec-iv_codes.html

IF your car is an 86-88 stang, you'll have to use the test lamp or voltmeter method. There is no functional check engine light on the 86-88's except possibly the Cali Mass Air cars.

Codes have different answers if the engine is running from the answers that it has when the engine isn't running. It helps a lot to know if you had the engine running when you ran the test.

Trouble codes are either 2 digit or 3 digit, there are no cars that use both 2 digit codes and 3 digit codes.

For those who are intimidated by all the wires & connections, see http://www.actron.com/product_detail.php?pid=16153 for what a typical hand scanner looks like. Normal retail price is about $30 or so at AutoZone or Walmart.

Or for a nicer scanner see http://www.midwayautosupply.com/detailedproductdescription.asp?3829 – It has a 3 digit LCD display so that you don’t have to count flashes or beeps.. Cost is $33.

4.) Post the codes and get help to fix them. Don’t try to pass with codes not fixed. Clearing the computer just temporarily removes them from memory, it doesn’t fix the problem that caused the code to be set.

5.) Be sure to do the testing on a hot engine. Drive for 15-20 minutes prior to taking the test to get operating temps up into the normal range. Do not shut off the engine while waiting for your turn on the test machine. An engine up to full operating temperature puts out fewer emissions.

Posted code 34
Code 34 Or 334 - EGR voltage above closed limit - Failed sensor, carbon between EGR pintle valve and seat holding the valve off its seat. Remove the EGR valve and clean it with carbon remover. Prior to re-installing see if you can blow air through the flange side of the EGR by mouth. If it leaks, there is carbon stuck on the pintle valve seat, replace the EGR valve ($85-$95).

If the blow by test passes, and you have replaced the sensor, then you have electrical ground problems. Check the resistance between the black/white wire on the MAP/BARO sensor and then the black/white wire on the EGR and the same wire on the TPS. It should be less than 1 ohm. Next check the resistance between the black/white wire and the negative battery post. It should be less than 1 ohm.

Note that all resistance tests must be done with power off. Measuring resistance with a circuit powered on will give false readings and possibly damage the meter.

Let’s put on our Inspector Gadget propeller head beanies and think about how this works:
The EGR sensor is a variable resistor with ground on one leg and Vref (5 volts) on the other. Its’ resistance ranges from 4000 to 5500 Ohms measured between Vref & ground, depending on the sensor. The center connection of the variable resistor is the slider that moves in response to the amount of vacuum applied. The slider has some minimum value of resistance greater than 100 ohms so that the computer always sees a voltage present at its’ input. If the value was 0 ohms, there would be no voltage output. Then the computer would not be able to distinguish between a properly functioning sensor and one that had a broken wire or bad connection. The EGR I have in hand reads 700 Ohms between the slider (EPV) and ground (SIG RTN) at rest with no vacuum applied. The EGR valve or sensor may cause the voltage to be above closed limits due to the manufacturing tolerances that cause the EGR sensor to rest at a higher position than it should.

This will affect idle quality by diluting the intake air charge