Mr. T wants to me to adopt 2 new cats

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Well after a brief intermission to go away on business I have been working on getting my truck through emissions testing and I am almost there which is good, because taking the train is starting to bother me. I have now checked timing, maf, confirmed the EGR and PAIR systems are functioning, filled it with 10% ethanol 94 octane and put in a "guaranteed to pass" additive.

The latest change is new 02 sensors and fixing an unnoticed bad vacuum hose at the vsv. This has made a significant difference but I am still failing on NOX. I now get a 2.2 nox reading where a 1.55 is a pass, and 1.48 is an average pass. Bearing in mind I had a 3.6 on the last test and that I started on NOX (nearly 7.0), I feel pretty close. I am still passing on HC and CO with above average results.

The question is, can anyone suggest anything that might get me over the final hump other than replacing the cats? I am leaning towards decarbonizing as one last option. In the world of outboards I have heard mixed reports about decarbonizing, including the fact that it can be detrimental on a warn engine. Is this a bad idea or a waste of money on an 80?

I know that bad carbon buildup can affect nox. I have not done a scope test to check for carbon buildup because this will cost me $100, but I am thinking that with 135k decarbonizing might be worth doing as pm anyway as long as it's not harmful. For $100 the dealer can use a compressed air gradual application decarbonizor that takes about 15 minutes through the throttle body and then give it an overnight soak. I don't know if this is a good system or not. I can obviously just use seafoam or something similar (autopar) for a lot less.

Any thoughts?
 
no, but with all that firewall insulation I don't know that I would notice a small miss. If I grip the transfer case shifter the vibrations at low rpm will sometimes feel a little rougher than at other times, but I have yet to spot a pattern to this. I have a new set of wires, cap and rotor to install when this is done.

Oh, and I have no water consumption and a rad flush last year was clean if you are heading where I think you are heading ;) (get it -"head-ing" hee hee)
 
Just asking. Last week with my truck having 130k on it, I didn't find much of anything in the way of carbon in the engine. None to be found in the EGR system as well. I did have a noticeable skip prior to the work and would have expected a dirtier inside. In an attempt to help the skip problem about 2 months ago I ran some of the Toyota injector cleaner through it. Maybe that helped clean things up.
 
Semlin,
I took mine in yesterday for smog check, all day I wondered if I would be in your predicament. (136k on odometer)
My cats must be in great shape, she passed with flying colors!!
well below the average.
Naturally the check engine lite came on a few days before, turned out to be O2 sensor, paid local prices (Dan is out fishing)
hope things work out for you soon :(
 
Eduardo, do you have full dyno testing? If so can you either post or pm me the results you got for HC, CO and NOX as well as your local state emission "pass" requirements. I have been querying the reasonableness of the local NOX requirement here since the "average" pass is within .07 g/km of a fail (e.g., tolerance is less than 5%)
 
Semlin, here in GA on the OBD-II trucks as long as it does not throw a code and the gas cap hold pressure it passes, does not help you much on the 93, I have never seen a 4 wheel dyno here not sure what they would do for you here

my understanding is nox is produced when combustion temps exceed 2500* dumping a metered amount of exhaust gas into the intake charge (EGR) is suppose to keep the temp below this amount

you say the EGR checks out, a lean condition could also raise combustion temps, many sources could cause that
 
Well decarbonizing did squat but I got my truck back on the road today for a year with a conditional pass of emissions after the dealership ran out of things to suggest other than new cats. Seems I met the annual spending limit on emission repairs for a vehicle that age. I can wait until next year to replace the cats. Meanwhile, eat my nox contaminated dust everybody :flipoff2: :beer: ;).

Before getting the exemption, I had an interesting chat with a provincial emissions test technical advisor today, whose job it is to advise mechanics trying to diagnose emission problems. This guy is an emissions guru and if you ever have a problem in your state see if they have one of these guys. I think he was very happy to speak to a member of the public who understood the systems rather than someone just yelling at him. Here are a few of his comments

1. the emissions test guys can diagnose what is wrong with your system using the second to second test results and the interactions of CO, NOX, NOX and CO2. In fact, he was even able to tell looking at my results that in the test where I used the additive I had some kind of alcohol in my fuel, not from the low readings but from the second to second interactions and there understanding of standard testing result behaviour. I might have been convinced much earlier that I needed cats if I had spoken to this guy because unlike my mechanic who said "I guess its the cats because we have eliminated everything else", he said "your hc and co results through the different parts of the test are typical of partial cat failure" and a bunch of other stuff that sounded cool and I should have written it down.

2. In Canada we use something called "IM240 testing to EPA cutoffs", which is a tougher standard than California and other US states also using full 4 wheel dyno testing. It includes variable load testing and it is much more common to have older cats show up as failing here than in US states.

3. He had strong views on what cats to use. If going aftermarket he said try to get something OBDII compliant if you go generic, and recommended Walker Clean Air Ultra Cats as having good precious metal loads. He was also very impressed that Kansas City Converters used OEM precious metal loads for rebuilds (that is what they tell me anyway), as he said most rebuilders don't. He also said that EPA or CARB certification for an aftermarket cat is not a very rigid standard, and that most aftermarket cats, even if OBD 2 compliant, are junk.

Anyway, I'm going for a drive!
 
I'm really surprised that Canada appears to be more stringent than California. I can understand the statement about “EPA certified” but I’m surprised by inclusion of CARB. I’ll have to ask my brother-in-law about that as up until about two years ago was head of auto emissions for Ford Motor Company. He always had business in California but never said anything about go to or dealing with Canadian officials. It could be someone else was responsible for foreign markets.
 
Simon,
i have the certificate with the results @ home I'll try and remember and get them to you.
I do believe it was a 4 wheel dyno unit, don't know how else they would do an all wheel drive vechicle ???
 
Nice final write-up to your headache. Could be something Junk could post to FAQ's as more of us have our aging beasts. California was supposed to implement 4wheel dyno emission testing, but I've heard nothing about it for some time now. Last time I was in, they still had to do the older testing, since there are only 2 wheen dyno testing facilities. Fine by me! All I had ever heard was that there weren't going to be that many testing facilities that would have the 4 wheen dyno's because of the expense, which only meant two things to me - it was going to be much more expensive to smog the LC and, in all likelyhood, I was going to be very inconvienced with the location of the few testing stations that there would be.

Anyone in the Republic of Kalifornia hear anything more about this?
 
Brentbba, so this should be posted as a faq? The way to beat emissions is to spend more than the annual limit? :flipoff2: :D

If someone posts some good cheap fixes to replace the whole exhaust, complete shot, then I'll faq it.
 
Semlin,
Test results:

RPM % CO 2 % O 2 HC CO %

670 14.9 0.1 5 (ave. 26) 0.00 (ave. 0)
2642 14.7 0.2 6 (ave. 11) 0.00 (ave. .1)

(max. 100) (max. 1.00)
(max. 180) (max. 1.10)

I'm not sure if the test machine was a full dyno test
 
thanks Eduardo, that's a different test. In British Columbia it is the average second to second result for HC, CO, NOX over a 3 minute drive test. The results are recorded in grammes per kilometer and are very different numbers from yours. They also give you a graph relating second to second results over the test to the speed the vehicle was travelling on the dyno.
 
Junk - no, entire thread does illustrate the numerous areas that can be tested if you've got a NOX problem with emissions. Spending more than the limit is beside the point, tho most states do have a limit if they test. Semlin has been thru the battles on this one and his trials and errors can be used for others to learn. That's my point.
 
Moralien, yep, that's the way it's done here as well.

Eduardo, from what I'd heard several years ago when Kalifornia adopted the dyno based emissions testing that they were going to have select shops with a very expensive setup to be able to test full time 4wd. I don't know if that meant static rollers or not. Just remember thinking it was going to be more expensive to test a 4wd vehicle than a 2wd. Haven't heard a thing since. We still have the older test for 4wd.
 
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