Maryland Emissions
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Maryland Emissions
I have a 95 f250-4x4 with a 460cid engine and a automatic trans. This truck will not pass the nitrogen or nox side of the test. I have done a complete tune up. All new filters and fluides. I don't have the check engine light on and the truck runs great. It even gets 12.5 miles to the gallon. Can anyone help. Someone said to replace the converter but its not clogged and nothing is loose inside. Please help.
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Joined: Jan 2002
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From: Baltimore
I've owned my 88 with the 4.9 six since new and it always passed the MD emissions. (300K miles)
The truck failed MD emissions about 4 years ago.
Replaced plugs, Oxygen sensor and EGR valve and it still failed.
To test the EGR valve you can apply vacuum to it while the engine is idling. When the valve opens, the engine should stall.
To test the Oxygen sensor you need a scan tool to monitor how fast it switches from rich to lean.
I decided there was nothing left so I replaced the cat and it took care of the problem.
Took the test again this year and it passed in the first 20 seconds of the test.
Make sure the engine is shut off and restarted before they do the test. I noticed they started doing this about 4 years ago.
I asked the emissions supervisor for Anne Arundel county why they shut the engine off and he said Ford recommended the computer be reset before any emssions test were done.
I told him that if you restarted the engine, the computer would not be in closed loop for at least a couple of minutes.
He agreed but said the computer should be in closed loop by the time all of the test were done.
The truck failed MD emissions about 4 years ago.
Replaced plugs, Oxygen sensor and EGR valve and it still failed.
To test the EGR valve you can apply vacuum to it while the engine is idling. When the valve opens, the engine should stall.
To test the Oxygen sensor you need a scan tool to monitor how fast it switches from rich to lean.
I decided there was nothing left so I replaced the cat and it took care of the problem.
Took the test again this year and it passed in the first 20 seconds of the test.
Make sure the engine is shut off and restarted before they do the test. I noticed they started doing this about 4 years ago.
I asked the emissions supervisor for Anne Arundel county why they shut the engine off and he said Ford recommended the computer be reset before any emssions test were done.
I told him that if you restarted the engine, the computer would not be in closed loop for at least a couple of minutes.
He agreed but said the computer should be in closed loop by the time all of the test were done.
Last edited by F150xlt; Sep 15, 2004 at 09:44 AM.
Lead Driver
Joined: Nov 2002
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From: Concord, NC
I misread your post and thought you said the check engine light was on - sorry about that. There can be codes set even though the light is not on, but I guess you have already checked that. Check the EGR valve passageway - as long as the valve is opening, the computer won't set a code, but that doesn't mean that exhaust gases are actually passing through the valve. The passage could be clogged and without the exhaust gases, the combustion runs hotter and creates more NOx emissions.
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Thanks for all the info. I did clear the EGR passages before I wrote this. I guess a converter is all thats left. The cost is around $500 and I was hoping to find out it was somthing else. Wishful thinking!!
Posting Guru
Joined: Jan 2002
Posts: 1,346
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From: Baltimore
Look up the Catco converter part number at this site
http://www.fle-online.com
Then order the part from http://www.summitracing.com
The part number may not show up on their web-site so call them at their 800 number. Should be less than $300 max for a direct fit.
http://www.fle-online.com
Then order the part from http://www.summitracing.com
The part number may not show up on their web-site so call them at their 800 number. Should be less than $300 max for a direct fit.
