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Old 08-22-2002, 08:16 PM
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Join Date: Aug 2002
Posts: 12
1988 260E Emission Problem and Questions

Greeting folks.

My 1988 260E failed the NYS emissions test with the following numbers, the limits are in parenthesis:

HC - 0.71(2.00)gpm
CO - 11.89(30.00)gpm
NOx - 4.60 (4.00)gpm

My NOx values where above the test limits. I have a new air filter, and new plugs( bosch platinums).

I have a question about the hose that's attached to the top of the cover that holds the air filter element. What is that hose? What does it do? What is the little vacum like hose that sprouts from it and goes somewhere under the air cleaner element housing? I'm asking because, the vacum hose broke off from the where it connects to the hose that attaches to the air cleaner and I accidentally pulled it too hard and it disconnected from whatever and where it was connected under the air cleaner. Any help would be greatly appreciated. Thanks.
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Old 08-22-2002, 08:21 PM
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Join Date: Apr 2000
Location: Lake Geneva, WI.
Posts: 1,676

Im no expert on how to fix your emmissions problems but i can give you some info on your other questions. First, You may want to consider switching your platinums back to copper plugs. Do a search on this site under "platinum spark plugs" you will see why. Also, the small vacuum line you are referring to is a breather hose for your fuel pressure regulator. They attach the line to your valve cover breather hose to protect it from contamination and for emmissions purposes if the fuel press. reg. becomes faulty and leaks. I do believe high NOx is related to high exaust temps which can be caused by lean mixture.....I think, don't take my word for it.
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Last edited by ADAM BOURASSA; 08-22-2002 at 08:26 PM.
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Old 08-23-2002, 04:57 PM
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Join Date: Mar 2000
Location: Fairfax, VA
Posts: 1,209
My 89 260E failed the NYS test -- until the well-informed tech at the Mobil station remembered that this particular car has to be hot, and he let it run awhile before repeating the test -- and it passed.

You might also have your injector seals checked. My mechanic did this by spraying some sort of (carb?) fluid around each injector with the emissions probe up the car's as-- er, tailpipe . On one or two of them, the CO/NOx values shot up, indicating the fluid was being draw in and burned, causing the increase in CO/NOx, and indicating a leaky seal. This can apparently confuse the car's computer into thinking it's running lean, causing it to inject more fuel and produce higher emissions.

The only other occasion that happened when when my O2 sensor had failed. After a new sensor was installed, all was fine.

Worst case: Have your mechanic adjust your fuel/air mixture until you are running very lean. You will pass. (Trust me.

Last edited by EricSilver; 08-23-2002 at 05:23 PM.
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Old 09-02-2002, 03:09 PM
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Join Date: Aug 2002
Posts: 12
I took the car in after running on the highway and it passed without a problem. I also pulled the Bosh Platinums and went with the Coppers. Thanks for the replies folks.
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