Emissions Q...

DIGITRUCK · Dec 27, 2005

Hey,

'88 XJ Cherokee Laredo 4.0L Auto.

I had a reman 4.0L put in around 5 yrs ago and put only 5k miles on it since I'm still rebuilding her in spare time. They used the old Manifold on new Longblock.

I also had a short K/N air filter put on and I think the Mech forgot to hook up my EGR (new at time also) by connecting the vacuum line to the EGR Solenoid (new too).

So, for the past 3 yrs I've been passing Emissions in NY w/o the EGR hooked up. And when I discovered it not hooked up I then reconnected it. Now, it fails Emissions testing for two years but "Benjamin" helped pass me. LOL
I would like it to pass legally though.

Here's my set-up: High-flow Cat and Flowmaster Muffler, Dual Electric Fans, all else stock. Cat has since been replaced with another High-flow Cat. The Muffler Shop said it was still good (I wanted to rule that out so I chged it)

My Temp Guage is a shade past 210 deg. One test failed when the vehicle overheated a year later it borderline passed (Nox passing is less than 2.50 mine was 2.49 all other readings lower) but it was borderline overheating (almost in the Red area on Temp Guage).

So I had enough of the Closed Radiator System and Installed New 3-Core All Metal CSF Radiator and Overflow Bottle, Changed Thermostat (Mopar 195 deg) all hoses and clamps too. Runs much cooler now even idling. Do you think upgrading this Cooling System would be enough to make it pass now?

btw - the Emissions Testing Shop uses no Big Fan in front of the vehicle.

What could be causing me to fail the Emissions test (High NOX)?

Thx, Phil

bj-666 · Dec 27, 2005

o2 sensor? sensors are the most common problem.

ahh unplut the egr valve again :laugh3:

DIGITRUCK · Dec 27, 2005

bj-666 said:
o2 sensor? sensors are the most common problem.

ahh unplut the egr valve again :laugh3:

Hey BJ,

Yeah, tell me about it. I changed most all the sensors too including the O2.

Funny thing with the EGR plugged in I seem to have more pep. Go figure.

Anyways my Emissions Test isn't until next Sept/Oct.

Does anyone think that upgrading the cooling system will help me pass the NOX?

Thx, Phil

87manche · Dec 27, 2005

I believe that High NOX is caused by high combustion chamber temps. So running the Engine at 250-260 during the test may have had an impact on the readings.

5-90 · Dec 28, 2005

Think so? It might. Will it? Probably not.

NOx production is usually a function of "flash" chamber temperatures - the peak temperature the combustion chamber reaches during actual combustion. As I seem to recall, atmospheric nitrogen dissociates and combined with atmospheric oxygen at about 1500-1600*F (I'd have to find the note for that,) and it does so in an unpredictable manner - which is why they're called "oxides of nitrogen" rather than a more homogenous "nitrogen dioxide," "nitrous oxide," or "dinitrogen pentoxide" (I think those are the three most common oxides of nitrogen - NO, N2O, and N2O5)

Anything that is meant to reduce oxides of nitrogen does so by somehow "polluting" the air-fuel mix, contaminating it with the aim of reducing actual combustion temperatures. Exhaust gas recirculation (EGR) does so by either tapping the exhaust stream and diverting it into the intake, or using cam overlap and exhaust reversion to allow some exhaust gasses back into the chamber. Other systems have been used - gross fuel injection (some of the heat in the "system" is used to transform the liquid gasoline to a vapour,) and "fogging" the intake stream with water ("water injection") or methyl alcohol ("methanol injection") work with a similar aim - by introducing a liquid into the intake stream, some of the heat in the "system" is used to vapourise the liquid rather than to dissociate and oxidise the nitrogen.

Intake "fogging" has been around since WWI/WWII - it was used in airplanes to reduce high-altitude knock, again, by consuming some of the heat in the system. As long as the source reservoir is full, this systems works quite well - with either distilled/RO-filtered water or methanol (DO NOT use tap water! This results in mineral deposits, which are worse than carbon!) Water injection/water fogging has the added advantage of keeping chamber carbon deposits to a bare minimum - the water is attracted to any carbon, is absorbed by the carbon, and breaks up the deposit when it flashes to steam (this is why I recomment the spray bottle trick for anyone with high NOx - it may be caused by carbon deposits, and you can break those up with just plain water. It essentially amounts to steam-cleaning the combustion chambers.)

5-90

DIGITRUCK · Dec 28, 2005

5-90 said:
this is why I recomment the spray bottle trick for anyone with high NOx - it may be caused by carbon deposits, and you can break those up with just plain water. It essentially amounts to steam-cleaning the combustion chambers.

5-90

Hey 5-90,

What an unusual screen name, does it mean anything?

Can you explain the "spray bottle trick".

Thx, Phil

5-90 · Dec 28, 2005

"The Spray Bottle Trick"

You do this anytime you think (or know!) if you've got a lot of carbon deposits in the chambers. High NOx or some spark knock is usually a good indication of this - but I tend to do it at every alternate smog (in my case, every four years.)

DISCONNECT the catalytic converter at the four-bolt flange, and let it hang. If it won't hang on its own, TIE IT DOWN! If there is carbon in the chambers, this will loosen it up. Carbon loosened from the chambers goes downstream - it won't kill your muffler, but it damn sure CAN kill your catalytic coverter! Make sure to have a new gasket for the flange - I don't recall the part number offhand, but it's available from Fel-Pro, and I probably buy a half dozen at a time. They're pretty cheap. If this is the first time you are taking this apart, you'll have trouble getting the nuts off - and they can be replaced with 3/8" UNC brass hex nuts, to make this easier later.

START the engine and let it warm up a bit. Not enough to make operating temperature (no need to waste that much fuel,) but just enough to let it get used to running.

DISCONNECT the air hose from the airbox, or remove the cone element from your air tube (this will give you something to do while the engine warms up...)

HOLD the throttle at a high idle - with a helper's foot on the accelerator, with your thumb, or do what I do - open the throttle by hand, grab a couple spare keys, and put them between the throttle bracket and the throttle stop (OUTSIDE the throttle body, Goofy!) You don't need to pick it up much.

Using a spray bottle full of DISTILLED or REVERSE OSMOSIS filtered water (NOT tap water!) and with the spray set on the finest mist it can managed, SPRAY a single mist into the open end of the air tube. WATCH for a black cloud coming out from the open pipe - this is carbon deposits (and if you can see them, you surely don't want them yacking up your catalytic converter!)

REPEAT every 20-30 seconds until you get NO cloud coming out from underneath - and then do it about four more times to make sure you get all the cylinders. If you don't get a cloud to begin with, do it about four times anyhow.

TURN OFF the engine, retrieve your keys from the throttle linkage, and reconnect everything. Use a new gasket for the catalytic converter and brass nuts to replace the steel ones, and a little RTV Copper on both sides of that gasket won't go amiss. I've not had this clog up a HEGO sensor - so no need to do anything there.

RUN-TEST your engine, to make sure you got it all hooked back up right.

You should be good to go for the next few years (unless you use cheaper gas than I do...)

I've been doing this on various vehicles for about 20 years, without incident.

5-90

DIGITRUCK · Dec 28, 2005

5-90 said:
"The Spray Bottle Trick"

You do this anytime you think (or know!) if you've got a lot of carbon deposits in the chambers. High NOx or some spark knock is usually a good indication of this - but I tend to do it at every alternate smog (in my case, every four years.)

DISCONNECT the catalytic converter at the four-bolt flange, and let it hang. If it won't hang on its own, TIE IT DOWN! If there is carbon in the chambers, this will loosen it up. Carbon loosened from the chambers goes downstream - it won't kill your muffler, but it damn sure CAN kill your catalytic coverter! Make sure to have a new gasket for the flange - I don't recall the part number offhand, but it's available from Fel-Pro, and I probably buy a half dozen at a time. They're pretty cheap. If this is the first time you are taking this apart, you'll have trouble getting the nuts off - and they can be replaced with 3/8" UNC brass hex nuts, to make this easier later.

START the engine and let it warm up a bit. Not enough to make operating temperature (no need to waste that much fuel,) but just enough to let it get used to running.

DISCONNECT the air hose from the airbox, or remove the cone element from your air tube (this will give you something to do while the engine warms up...)

HOLD the throttle at a high idle - with a helper's foot on the accelerator, with your thumb, or do what I do - open the throttle by hand, grab a couple spare keys, and put them between the throttle bracket and the throttle stop (OUTSIDE the throttle body, Goofy!) You don't need to pick it up much.

Using a spray bottle full of DISTILLED or REVERSE OSMOSIS filtered water (NOT tap water!) and with the spray set on the finest mist it can managed, SPRAY a single mist into the open end of the air tube. WATCH for a black cloud coming out from the open pipe - this is carbon deposits (and if you can see them, you surely don't want them yacking up your catalytic converter!)

REPEAT every 20-30 seconds until you get NO cloud coming out from underneath - and then do it about four more times to make sure you get all the cylinders. If you don't get a cloud to begin with, do it about four times anyhow.

TURN OFF the engine, retrieve your keys from the throttle linkage, and reconnect everything. Use a new gasket for the catalytic converter and brass nuts to replace the steel ones, and a little RTV Copper on both sides of that gasket won't go amiss. I've not had this clog up a HEGO sensor - so no need to do anything there.

RUN-TEST your engine, to make sure you got it all hooked back up right.

You should be good to go for the next few years (unless you use cheaper gas than I do...)

I've been doing this on various vehicles for about 20 years, without incident.

5-90

Hey 5-90,

Wow! Sounds Good. Unfortunately, if I do this I would most definitely KILL my CAT. My CAT is WELDED on.

Would I get any adverse effects to my CAT if I removed the EGR VALVE and poked a coat hanger and sprayed carb cleaner in the opening?

btw - What does "5-90" represent?

Thx, Phil

5-90 · Dec 28, 2005

Hmm - dunno. The issue you're likely to run into, in any wise, is the carbon suddently in the exhaust getting into the converter matrix and coating it - which would result in converter 'clogging' - not much much causing backpressure, but certainly causing the converter to be useless. I'm not sure how to get carbon coating off of the ceramic matrix in the converter - you might be better off just pulling the downpipe off of the collector (which will also work - but the converter flange is easier to get to.)

Anyhow, key is the fact of disconnecting the exhaust upstream of the converter - so you'll be running a short, open exhuast and not contaminating the catalytic converter.

Cleaning the EGR passages isn't such a bad idea, either - just make sure the exhaust is open so the carbon going through won't coat the matrix (you can do this as part of "the bottle trick" if you want to get it out of the way all at once.)

You should have gotten a PM as to the other question.

5-90

Emissions Q...

DIGITRUCK

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bj-666

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DIGITRUCK

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87manche

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5-90

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DIGITRUCK

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5-90

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DIGITRUCK

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5-90

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