Failed Emission Test 90 Ford Taurus

I failed my Emission test today with a 1990 Ford Taurus Wagon. The HC level at 15mph passed but at 25 it was double the limit. The co% failed at both
15 and 25mph (the levels were .42 and .77 the limits are .37 and .53) Finally the NO ppm were really high 2685 and 2617 compared to the limits of 1220 and 1167 respectfully. Any help you all have as to the problem of these failures will save me lots of $$$
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There could be lots of causes. You haven't even told us which engine.
First, how long since you replaced the spark plugs, wires, distributor cap and rotor (if equipped)? How about the air filter? Has the EGR valve ever been cleaned?
CJB

level
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First-Your car is running rich. Could be lots of reasons. I would tune it up (plugs at least). I would then put an O2 sensor on it because it has probably never had one. After that I would scan it for codes. KOEO, then KOER. You will then likely find a problem with the EGR(that will cause high NOX. If not(no codes to fix) it will likely need a cat converter to cure the high NO. The standard you show for passing are pretty high so it shouldn't be too tough to reach them. Good Luck
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On Wed, 26 Oct 2005 11:18:27 -0400, "LocalHero"

From first glance I'd suspect running lean. Lean missfire makes HC go up. Also causes elevated NOX. Being 1990 you don't have OBD2 or missfire detection.
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snipped-for-privacy@sny.der.on.ca wrote in wrote:

Are there any indications, otherwise?
At those levels, I would suspect that engine isnt running all that great.
Like Clarence said, ALL THREE being high look like non-combustion rather than incomplete.
Does your car have a problem with hesitation, pinging, poor starting, etc.... and does it have a MAF sensor?
Sounds like it needs a cleaning.
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if I remember the 90 has no MAF
wrote:

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wrote:

I know how you came up with lean but.....the HC isn't high enough for a misfire IMO, it looks like leftovers from too much gas (co was too high also)
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I had a test fail 92 Beretta, that passed the second time simply by leaving out the air cleaner during the test. That extra air really brought the numbers down more than I had expected. Must have been running rich.
It's not a Ford, but the point is the same.
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OR it was properly warmed up the second time. (or the filter was VERY dirty)
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It was an elcheap-o filter which I noticed (upon rmoval) had a pretty low airflow look to it. Sure it was dirty but no doubt the motor had other issues. Removal of the filter got me thru the test, and I put a better quality filter in afterwards. But no doubt the motor needed other attention.
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Puzzled Ed wrote:

No, the point is that something is wrong in the fuel control causing the emissions to be too high. Removing the air filter to mask the problem may lead to a high dollar repair later that involves more than emissions. So does unplugging a vacuum line, adding rubbing alcohol to the tank, mothballs in the tank, advancing the timing, etc, etc, etc. to beat emissions.
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On Wed, 26 Oct 2005 23:38:11 GMT, "Shoe Salesman"

Try this on for size. one or more cyls running lean misfire - causing O2 sensor to read LEAN (it senses oxygen in the exhaust because the cyl misfired) so it richens up the entire fuel map. The enriched mixture throws the CO off, so you end up with high hydrocarbons from the misfire, highe NOX from the lean running cyls, and high Co from the enriched mixture trying to compensate for the leak.
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wrote:

the enriched mixture trying to compensate for the leak.
Yep, that's the scenario I meant when I wrote "I know what you mean by lean" ( first sentence) I'll still bet on too rich like an O2 problem and EGR problem. But we will probably never know unless localhero tells us...... :(
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LocalHero wrote:

Has your MPG improved/been improving since the last test?
If so, I would suspect a EGR problem based on the NO figures.
Rob
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