Can you tweak down NOx emissions?

V

vettewars

Registered User
I have 2 - 89 5 Speeds....and both have failed emissions on NOx in Jersey....this latest reads 1088 and standard is 1077.

Is there any easy way short of installing a new cat to get the NOx down a bit?. Other readings on HC and CO are very good.
Otherwise car runs great, no misses, etc....

I understand cats degrade around 100K miles, and this one has 140K on it....but I've never had any of my other Fords, even with higher miles, have any problems with NOx....

For some reason do the SC cats go "early" at around 120 to 140K?

I suspect the answer is you have to have the 3 way cat to perform this breakdown of NOx to N and O....and maybe for some reason the SCs put a higher "load" on the cats....

Has anyone succeeded finding a 2 into one cat that neatly fits where the resonator is?
 
I don't think the early style cats will help with NOx emissions. That is caused by high combustion temps.

These recent threads have some info:

http://66.36.160.39/forums/showthread.php?s=&threadid=35225

http://66.36.160.39/forums/showthread.php?s=&threadid=35865


I was close like you are and just ran a tank of injector cleaner, highest octane gas I could get and pulled the octane plug. Then I was able to pass the Ohio dyno test.

You could also check the EGR on your 89, since it can also lower combustion temps when working properly.
 
I sure hate to disagree with George, but....

My 35th with almost 170K failed the NO here in SoCal. It only had 2 CATs and replacing them was all it took to pass. It was re-tested same place, same conditions. :confused:

Lee
 
Lee, it doesn't bother me at all! LOL Most of us are just seeking the elusive correct answer.

The cats will only make a difference if they are 3-way as opposed to 2-way cats. I thought the early SCs with two cats only had 2-ways, but I could be wrong on that point. If you had yours replaced with non-stock cats, they could have been 3-ways and would have lowered the NOx. This guy is so close, I'll bet the octane plug will get him back to passing levels.
 
Lee
Where did you get your cats? Aftermarket? I will be putting engine and trans in around the years end. I want to replace the cats at that time. I also have around 175,000 miles on these cats and had a hard time last smog. I will be do in May again. I too, live in southern California. Seems like they change the NOx standards all the time.

Later
Denny
 
In Summer of 2002 I had a real hard time passing NOX here in Northern VA even after putting on two brand new Catco three-way cats. My problem seemed to be locating the cats farther back away from the engine than stock when I replaced my entire exhaust system to straightn out the down tubes.

I suspect I will still have problems next Summer when it's time to run the check again. I'm sure I'll be asking you all about it then.

My 93 stick came stock with no EGR and 3 cats.

Jon
 
NOX is only affected by high temps..

The only thing that affects NO2 levels is the engine temps and EGR function. The EGR (Exhaust Gas Recirculation), takes exhaust gas during cruising speeds and re-introduces them into the engine for better emissions. The two things that cause high levels are>>>>>

1) High engine running temps.....

2) Poor or non-functioning EGR Valve or conponents.

The first...Engine temps can be helped by keeping the engine cool during testing. In other words, run the cooling fan before going in and try to get the engine cool. Two is to check EGR function. Chances are after 140,000 miles the EGR is clogged or not working.

In non-EGR SC's, the NO2 emmissions are normally high. Mine was 1042 in New Jersey.

Good luck and take Georges advice, the octane plug will increase timing and help.

Big thing is to go when there is NO LINE!!!! This will reduce engine temps and cause you to pass.

Chances are though the EGR is not working properly.


Don
 
Re: NOX is only affected by high temps..

lube70 said:
The only thing that affects NO2 levels is the engine temps and EGR function. The EGR (Exhaust Gas Recirculation), takes exhaust gas during cruising speeds and re-introduces them into the engine for better emissions. The two things that cause high levels are>>>>>

1) High engine running temps.....

2) Poor or non-functioning EGR Valve or conponents.

The first...Engine temps can be helped by keeping the engine cool during testing. In other words, run the cooling fan before going in and try to get the engine cool. Two is to check EGR function. Chances are after 140,000 miles the EGR is clogged or not working.

In non-EGR SC's, the NO2 emmissions are normally high. Mine was 1042 in New Jersey.

Good luck and take Georges advice, the octane plug will increase timing and help.

Big thing is to go when there is NO LINE!!!! This will reduce engine temps and cause you to pass.

Chances are though the EGR is not working properly.


Don
Click to expand...
A little bit of clarification. Cooling your car more will not change your Nox levels. High Nox does not come from higher engine temperatures, but from higer combustion temperatures. In a simple, but only partly correct, analogy it would be like the car is running lean. To "cool" the combustion temps back down, the EGR essentially throws foul air back into the intake which dilutes the charge somewhat and it doesn't burn as well and hence cooler. This is how EGR lowers the Nox emmissions.

For the non-EGR cars, Nox is addressed by a 3 stage catalytic converter. The first 2 stages are the normal HC control, and the last is the Nox chamber. EGR equipped cars have 2 stage cats which also tend to be cheaper to replace. The dissadvantage of EGR is its a device with moving parts moving hot gas. It will tend to wear out and/or need service.

The EGR was commonly used on the 5speed SC. I haven't heard anyone report having one on an AOD car.
If your cats are good, and you don't have any parts causing a lean condition (bad MAF, clogged injectors, bad FPR, bad EEC tuner, vaccuum leaks!!), then the AOD will pass emissions. You can have your cats tested at just about any muffler shop.
 
jonroe said:
My problem seemed to be locating the cats farther back away from the engine than stock when I replaced my entire exhaust system to straightn out the down tubes.
Click to expand...
This is a common side effect of moving the cats back. You generally want them as close as you can get to the exhaust manifold so that the exhaust gas doesn't cool much. What some people do in this circumstance is wrap the exhaust downpipes with header wrap to keep the heat in.
 
Just a couple of quick notes guys.

1. My 35th had 2 CAT's & no EGR. (The current titanium I bought new 4/90 is the same)

2. When trying to find a replacement PCM a few years ago I found that there were 3 for '90; a 5spd w/EGR, an AOD w/EGR and an AOD wo/EGR.

TbirdSCFan's explaination, and George's comment about 3 way CAT's would support what happened when my 35th passed after replacing the CAT's.

Lee
 
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