Gross Polutter High No

I have searched and have foound for High NOx is cause by a lean condition.

Well I have Std Champion Plugs 2 yrs old and a 2 year old CAT. The Tech found a slight overheating issue. Seems to be leaking at the heater box valve, probably a heater house, but could be a valve. In normal driving conditions my temp runs right at 210, when driving around in the summer the temperature climbs to 215, according to my highly accurate OEM temp gauge.

The Smog tech recommended fixing the coolant leak and getting a new CAT. If the plugs look bad I'll replace them and then search for a vacuum leak or an exhaust leak.

Here are my readings:
Max 517 Mine 1771 @ 15 mph
Max 770 Mine 1666 @ 25 mph


Any other sugestions?

Thanks,

ChuckD

last time i failed for high NO emissions to. i replaced the cat and they went back to normal levels. my old cat was less than two years old and it caused me to fail also.

ChuckD said:

I have searched and have foound for High NOx is cause by a lean condition.

Well I have Std Champion Plugs 2 yrs old and a 2 year old CAT. The Tech found a slight overheating issue. Seems to be leaking at the heater box valve, probably a heater house, but could be a valve. In normal driving conditions my temp runs right at 210, when driving around in the summer the temperature climbs to 215, according to my highly accurate OEM temp gauge.

The Smog tech recommended fixing the coolant leak and getting a new CAT. If the plugs look bad I'll replace them and then search for a vacuum leak or an exhaust leak.

Here are my readings:
Max 517 Mine 1771 @ 15 mph
Max 770 Mine 1666 @ 25 mph


Any other sugestions?

Thanks,

ChuckD

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Sounds like good advice to me. What were the other emission levels, were they OK?

I'm in the same boat Chuck.
Here are my numbers.



I just replaced the plugs and pulled the valve cover off to clean that up. I'm hoping the CCV system is the problem. If that doesn’t do it I guess I'll be doing the Cat/O2 thing. I've never put a cat on it so if you guys are going thought them every two years I guess that may mean its time. How long are they supposed to last?

Make sure O2 sensor is new, map and egr are working correctly,
engine is TOTALLY warmed up. All this was still not enough for
my 258k engine and hollowed out cat. Replaced cat and aced test.
Run Chevron or Shell 87 octane, stay away from metanol blends for
the test.
3 years ago was the first time for NO testing in Calif.

A couple other bits of advice.

1. Change the air filter (if you haven't already)
2. Change the oil and filter (NO Fram filter please)
3. Be sure your gas tank is full before you take it in for the re-test.
4. Good Luck!!!

Cats are supposed to last for the life of the vehicle. When they fail it's usually because the engine is running rich and the cat melts then sounds like rocks rattling. New cats come with a card explaining what I've just mentioned. They are not hard to change. You didn't emntion the year or miles but I replace the original on a 96 with 142k miles becaused it rattled so I also replaced the o2 sensor.

JoBo said:

Cats are supposed to last for the life of the vehicle. When they fail it's usually because the engine is running rich and the cat melts then sounds like rocks rattling. New cats come with a card explaining what I've just mentioned. They are not hard to change. You didn't emntion the year or miles but I replace the original on a 96 with 142k miles becaused it rattled so I also replaced the o2 sensor.

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I havent seen one yet that lasts the life of the vehicle one misfire condition for a relitively short time caused by anything will put your converter efficiency in the dumpster dude (they dont need a total meltdown as you described). And they dont always rattle when they are bad either, when they do you usually have more clues than a failed E.T. such as a plugged exhaust from little chunks of catalyst material in the muffler plugging it up or at least restricting it enough to tell at a good engine load.....

Bryan C. said:

Sounds like good advice to me. What were the other emission levels, were they OK?

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Yes, the others were in acceptable levels.

Sorry I forgot to mention it's a 93' HO motor with about 150-175k on it. I upgraded the speedo about two years ago and my speedo gear in my Tcase is still stock. So it's doesn't read correctly with 4.88 gears and 33" tires.

Well, I'm not gross anymore, but :helpme:


NO: 722 @ 15 mph, MAX is 517 Ave 136 FAIL
265 @ 25 mph PASS MAX is 770

HC: 13 @ 15 mph, Ave 19
8 @ 25 mph, Ave 12

CO% .05 @ 15 mph, Ave .06
.01 @ 25 mph, Ave .05

So, I still have a NOx issue.

This is what I have done sofar,

New Rad and replaced all the hoses and heater valve, flushed core, Temps were Avg 210, now Avg Temp is 180.

Removed CAT, Did the 590 distilled water spray and seafoam, did not notice any carbon from exhaust.

Ran injector cleaner through fuel system

Installed New Catco CAT

R&R Spark Plugs, Std Champions

New O2 sensor

Clecked for Vacuum leak

The Tech guy says I'm running lean, so I can only think of two more things:

Make sure manifold is tight

R&R Injectors, (anyone have any to spare?) :wave:

Am I headed in the right direction? :banghead: The engine has 170k on it and runs strong. If I can't figure this out, then I will just have to Non-op it and build a stroker motor! Like my wife will let me do that! :gag:

Nothing to spare, but have you cleaned the injector nozzles? That could also cause a "lean" condition, by restricting fuel flow.

2-3 ounces of acetone to 10 gallons of gasoline (or, 4-6 ounces total) works well for "blowing out" the injectors. I didn't notice any increase in fuel mileage, but I did catch a slight decrease in operating temperature (as read by an IR non-contact thermometer to the "hot" radiator tank,) and that would indicate that an incipient "lean" condition was corrected, most likely.

I now treat my DD's with acetone about every six weeks (I just give my wife a bottle, and tell her to put it in right before the next time she fills up. Same goes for me - but I've got a batch of four-ounce bottles anyhow.)

5-90

5-90 said:

Nothing to spare, but have you cleaned the injector nozzles? That could also cause a "lean" condition, by restricting fuel flow.

2-3 ounces of acetone to 10 gallons of gasoline (or, 4-6 ounces total) works well for "blowing out" the injectors. I didn't notice any increase in fuel mileage, but I did catch a slight decrease in operating temperature (as read by an IR non-contact thermometer to the "hot" radiator tank,) and that would indicate that an incipient "lean" condition was corrected, most likely.

I now treat my DD's with acetone about every six weeks (I just give my wife a bottle, and tell her to put it in right before the next time she fills up. Same goes for me - but I've got a batch of four-ounce bottles anyhow.)

5-90

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Well, I have done the Acetone in the past to try to get the extra MPG's. I have Acetone and and baby jar 4oz .

So do I just run it in the tank or is there something else I can do as far as removing them and cleaning them?

You can just run it through the fuel tank, or you can soak the entire injector in acetone (I've done it) if you're inclined to remove them. However, soaking them might get the core passage, but not the pintle and seat (unless you have some way to power them up.)

You are correct that high NOx is caused by a "lean" condition - has to do with heat transfer into the fuel, and the flash temperature caused by rich-vs-stoich-vs-lean conditions. As you lean out the mixture, the flash temperature increases. Once it reaches about 1500*F (as I recall,) the nitrogen in the air oxidises and you get NOx formation. This is later dissociated by a "reduction" step in the catalytic converter - that's why a catalytic coverter can also often correct NOx - the reduction stage has failed somehow (probably gotten crapped up.) That's why water and water/alcohol foggers can reduce NOx - they reduce flash temperatures by adding to the "heat capacity" of the system. Too bad the Kalifornia Smog Nazis won't let us run them (I checked with CARB...)

5-90

It's reputed that a K&N/other high-flow filter upgrade causes the motor to run rich, so if you're running lean, perhaps a filter upgrade would cause your lean condition to correct to a stoichiometric (and net a few extra HP/MPG)?

I am addicted to acetone. I don't know if it helps my mileage at all, but my motor seems to have better transient response, and more torque at a lesser throttle opening, with it. I have a 1-gallon jug in the back seat, and a 2-fl. oz. measuring cup. I use somewhere between 1.5 and 2 fl. oz. per 5 gallons at every fill up. I don't have emissions testing in NY (O2 sensors? Check. Catalytic converter appears to be there? Check. You're good to go!), so I don't have any numbers to share.

If your cat requires replacement (federal law prohibits replacement of a functional one), you may as well get an aftermarket high-flow unit, which will often work the same/better than OEM, and also offer less backpressure.

I have access to an ultrasonic cleaner, so botomline, do you think that there is any gain to R&Ring the injector over just running Acetone through the fuel system?

Did you change your thermostat too? What temp rating is it?

Bryan C. said:

Did you change your thermostat too? What temp rating is it?

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Brand new Prestone High Performance 180!

ChuckD said:

I have access to an ultrasonic cleaner, so botomline, do you think that there is any gain to R&Ring the injector over just running Acetone through the fuel system?

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If you have access also to a fuel injector connector (should be available at the local under "HELP!") a 9V battery, and a momentary switch, that should work.

Connect the battery to the FI connector via the switch, and "pulse" the switch while the injector is cleaning. This will help to get the pintle and seat clean, and make your job a little more thorough. I think ultrasound is how they're "professionally" cleaned, but don't hold me to it...

5-90

ChuckD said:

The Smog tech recommended fixing the coolant leak and getting a new CAT. If the plugs look bad I'll replace them and then search for a vacuum leak or an exhaust leak.

Here are my readings:
Max 517 Mine 1771 @ 15 mph
Max 770 Mine 1666 @ 25 mph


Any other sugestions?

Thanks,

ChuckD

Click to expand...

Get a new Cat. :laugh3: Seriously, it should only around $100 installed. 210 is completely normal for a 4.0L I've had a dozen of them or more in YJs, XJs, ZJs and they always run at that old or new. If you check engine light comes on, I have a scanner that can read 86+ if you need to use it let me know.

If your failed within 2 year of getting a new cat, then you will probably need a new O2 sensor as well as you are running to rich. Your check engine light should be coming on though telling you something is out of range/order. My Check Engine light wasn't coming on eventhough my 96' XJ had the O2 sensor wires cut by the previous owner? I don't know why they were cut, but the Check Engine light should always flash on when you start your Jeep. If it doesn't you probably have a bad bulb and/or a bad fuse. I just stole a fuse from the "Coolant Low" that always alloys me and off I was back to Smog N Go to pass.

Get a new cat and run over to Smog N Go, you'll pass with flying colors and you will get a print out saying how glad the State is that you are helping with their high standards of eliminating excess pollution or something along those lines. You will also pass easier now with the temps being cooler then you will when we are baking in 100+ degree weather in the Summer.

Sorry for the novel, I've been away for awhile. :laugh3: Good luck with the test Chuck.

Troy