Failed vehicle inspection

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Jan 5, 2004 | 01:52 PM

cmoore99

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From: Dallas, Texas

Failed vehicle inspection

I have a '92 F150 with the 4.9L engine and M5OD transmission. I have just over 125000 miles on the truck. I am the original owner. Took it in for inspection today and failed the emission test. The high speed test for Nox (ppm) failed with a reading of 1055. The form they gave me states that the standard reading for this test is 818. All of the other high and low speed emissions tests passed. The check engine light has not come on. Does anybody have any idea what could be causing the high Nox reading? Heck I do not even know what Nox stands for. Any help/insight you can give me will be appreciated.

Jan 5, 2004 | 06:45 PM

924x2150

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From: Langhorne, PA

I own a 1992 4.9L, I am looking at my Pennsylvania emissions statement for my truck. There are 3 readings, Carbon Monoxide (CO), Hydrocarbon (HC), and Nitric Oxide (NO). All I know about your reading NOx, is that it is called oxides of Nitrogen which is a measurement of the combination of NO nitric oxide and NO2 Nitric Dioxide.

On my truck, the CO limit was 1.24%, mine read 0.00/The HC limit was 147, mine read 22/ the NO limit is 990 and I was 147.
I couldn't find anything on the internet about possible causes for this, but I think your problem could be anywhere from the oxygen sensors, to computer, or even a bad CAT or smog pump. I would see a pro and get it repaired. Can you get a waiver if you can't fix it??

Jan 5, 2004 | 06:52 PM

dbuck50

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My 5.0 didn't pass Illinois emissions until I replaced the timing chain. They don't test NO, but the HC was through the roof. A stretched timing chain (5 degrees or more of play) will cause lousy emissions.

Jan 5, 2004 | 07:59 PM

ahatch98

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From: Bulter MO

oxides of nitrogen come from to high combustion tempetures. I would be looking at either egr or cooling in your motor. Other than that look at anything that will cause to high of combustion.

Later
Allen

Jan 5, 2004 | 08:59 PM

StrangeRanger

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From: Copley, OH

NOX can also come from running too lean. If you're still running your original O2 sensor at 125K, it's past time for a change. They crud up over time and while they don't fail they give bad O2 readings but won't set an error code

Jan 6, 2004 | 02:03 PM

steell

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From: Indiana

And of course there is the usual suspect, vacume leak

Steve

Jan 6, 2004 | 02:39 PM

cmoore99

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From: Dallas, Texas

Thanks for all of the replys. I am running an O2 sensor that is 10 plus years old. That may be the problem. Anyway I turned it into the Ford House this morning to let the pros figure it out. I will let you all know what they find. Thanks again for all of the replys.

Charlie Moore
Dallas, Texas