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'92 940 Emissions/ Catalytic Converter Question 900

posted by someone claiming to be texdavek on Thu Oct 14 08:14 CST 2004 [RELATED]

My '92 940 is failing its state emissions test with excess NOX. So far, I've replaced the distributor cap and rotor, the oxygen sensor, and the engine been tuned for about a year. Last summer (2003) I replaced the catalytic converter with a aftermarket converter, when it failed the emissions test last year.

Giving up, I've taken the car to the dealership. They are saying I need to replace the catalytic converter -- another $500, saying that their experience is that the aftermarket converters don't distribute the exhaust gases sufficiently to do their work. My question to the forum - "is this reasonable?", "do I need to replace the converter this quickly?" My bill is already $450 -- add another $500 and I'm at a whopping $950, so I'm all ears. Thanks guys.

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'92 940 Emissions/ Catalytic Converter Question 900

posted by rsbrink on Fri Oct 15 13:18 CST 2004
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last visit: Thu Nov 22 21:23 CST 2012

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I have the same problem with high NOx on my 87 740 230F. CO and HC are very low. I think it is the converter also which is an aftermarket (CATCO) less than a year old. I also put in a new oxygen sensor which did little. The only thing that was recommended to me was to put the cooler engine thermostat in and get a new radiator so it runs cooler. What brand converter did you put in?

Any other opinions??

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'92 940 Emissions/ Catalytic Converter Question 900

posted by Sumerduckman on Thu Oct 14 10:14 CST 2004
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last visit: Tue Aug 21 11:31 CST 2007

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Sure sounds like bunk to me. There are a lot of cars and trucks running around with aftermarket cats that pass just fine. Assuming all of the normal engine maintainance items are up to snuff, and that there is no issue with a bad egr valve etc, and since you did not list which engine you have and what the test numbers were, you could try running a tank of quality premium gas through it and see if that helps. Lower combustion chamber temps.The high price gas they have been selling the last few years is real garbage. I am fimly convinced it is the cause of a lot of marginally failed tests.

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'92 940 Emissions/ Catalytic Converter Question 900

posted by someone claiming to be texdavek on Thu Oct 14 10:55 CST 2004 [RELATED]

Thanks. The engine is the B230F non-turbo. We're not talking a marginal failure here. The NOX numbers are significantly high -- something in the range of 1400 when the threshold to pass is something like 800 or 850.

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'92 940 Emissions/ Catalytic Converter Question 900

posted by someone claiming to be sredwine on Thu Oct 14 11:11 CST 2004 [RELATED]

It could be high combustion temps caused by lean mixture-check intake hoses,try looking for vacuum leaks with carb cleaner-you may have a bad intake gasket or injector O-rings.If your car has EGR,that is another possiblity.Also,do you have the intake air heater valve?If it's stuck in "hot" position,this could be the problem-see FAQs.Hope this helps. sredwine 94 940T 150K

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