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  #1  
Old 11-15-2004, 10:56 AM
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1989 W126 300SE Passed Emissions Test

By that much.

The 15 mph test was fine. The 25 mph test wasn't so good.

Test_______limit__ reading
HC ppm____ 103__ 54
CO% ______ 0.63_ 0.22
NO ppm____ 729__ 727

Looks like I have some vacuum leaks
I'm going to fix them so the reading is lower.

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Warren

Currently 1965 220Sb, 2002 FORD Crown Vic Police Interceptor

Had 1965 220SEb, 1967 230S, 280SE 4.5, 300SE (W126), 420SEL

ENTER > = (HP RPN)

Not part of the in-crowd since 1952.
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  #2  
Old 11-15-2004, 06:05 PM
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What makes you think that you have vacuum leaks?
The high NOx would normally be caused by a suspect/defective EGR system.
Your HC & CO readings are very good.
Often, vacuum leaks are accompanied by elevated HC readings.
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  #3  
Old 11-16-2004, 12:55 AM
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My 300SE doesn't have an EGR. I figured vacuum leaks because the rubber bits look like the original ones and are hard and one is cracked near the end of it.
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Warren

Currently 1965 220Sb, 2002 FORD Crown Vic Police Interceptor

Had 1965 220SEb, 1967 230S, 280SE 4.5, 300SE (W126), 420SEL

ENTER > = (HP RPN)

Not part of the in-crowd since 1952.
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  #4  
Old 11-16-2004, 08:26 AM
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nox

High nox can be caused by a clogged or malfunctioning catalytic converter. But before I assumed that, I would drive down the tank to empty, put diesel fuel injector cleaner in there, drive the car hard until about 1/8th a tank is left then go test again while the car is hot. A dirty intake system can cause high nox, I have seen it and also read it (a reason why so many injection cleaners claim they help emissions, they can). You may have a vacuum leak anyway. But if that were causing this problem I would expect to see the other readings off more especially if the car fuel/air were manually adjusted to work around the vacuum leak to improve idle. But these are sensitive systems so who knows what anomaly can occur in al circumstances.
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  #5  
Old 11-16-2004, 12:35 PM
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Also using a grade of fuel other than supreme in that model can increase NOX by more rapid burning. The jury is still out, but someone posted here a few months ago about failing NOX as a gross polluter until he changed his radiator. I want to test that theory, but the 88 and 90 300SELs I have been fighting with have been failing in the HC category.

Peter
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  #6  
Old 11-16-2004, 01:03 PM
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The rate of flame propagation does not vary significantly between gasolines with different octane ratings as long as there is no detonation, and the same applies to peak temperature of the flame front, which is where NOx forms. "Premium gas burns slower" is a myth!

To the thread originator - I don't think there is a "problem" with your converters, but it will help in diagnosis if you would post the entire test results for both 15 and 25 MPH including the 02 content.

Duke
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  #7  
Old 11-16-2004, 07:23 PM
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If fuel grade doesn't make a difference,then there a whole lot of us out here that have misinformed by articles in professional journals, the mfgs of the testing machines, and I believe the State of California, but don't quote me on the last, because I have to check my references.


Peter
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  #8  
Old 11-16-2004, 10:26 PM
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Make a difference regarding...?

The "premium fuel burns faster" myth probably originates from not understanding the nuances of combustion and the difference between normal and abnormal combustion.

If you use fuel with insufficient octane in an engine and it detonates then, yes,combustion is "faster" because detonation is virtually instantaneous, but this is ABNORMAL combustion, and most engines will not survive long under continuous detonation, so the point is somewhat mute.

If you use a higher octane than the engine needs, there is no signficant difference in normal combustion flame propagation rate, and there would be no statistically signficant difference in emissions. If the octane rating is too low and the engine detonates, then it's a whole other ballgame.

Duke
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  #9  
Old 11-16-2004, 10:45 PM
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We may be talking about 2 different things here.
Fuel " grade ", i.e. octane rating, vs. Fuel composition, i.e. oxygenated, ethanol-blended, etc.
In which case I believe there to be a slight difference in exhaust emissions.
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  #10  
Old 11-17-2004, 12:04 AM
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The idea of oxygenated fuel was to provide more O2 to help oxidize CO and HC on pre-O2 sensor cars, which are getting pretty rare nowadays! It should also function the same way on an O2 sensor car during warmup prior to going into closed loop operation, however, evidence indicates that oxygenated fuels do little to reduce emissions, but they are more expensive to produce and increase fuel consumption about three percent because they have less energy. Their cost far outweighs their benefits in even the most "liberal" economic analyses.

In closed loop operation an O2 sensor engine will just richen the mixture slightly to maintain the target near zero 02 reading in the exhaust.

The Schwarzenegger administration has actually petitioned the EPA to eliminate the oxygen requirement for California gasoline. The EPA is the source of the requirement, and it's more about placating the farm lobby than clean air.

Duke
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  #11  
Old 11-17-2004, 02:04 AM
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OK, I'll post the results from the 15 and 25 mph tests in the morning.
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Warren

Currently 1965 220Sb, 2002 FORD Crown Vic Police Interceptor

Had 1965 220SEb, 1967 230S, 280SE 4.5, 300SE (W126), 420SEL

ENTER > = (HP RPN)

Not part of the in-crowd since 1952.
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  #12  
Old 11-17-2004, 10:31 AM
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The 15 mph test at 1504 rpm, dilution 15.6.

Test _______Limit_____Reading
HC ppm_____106______29
CO%_______0.59______0.10
NO ppm_____800______312


The 25 mph test at 1527 rpm, dilution 15.8.

Test_______limit______reading
HC ppm____ 103_____ 54
CO% ______ 0.63____ 0.22
NO ppm____ 729_____ 727

I don't know what dilution is but I added it here.

The car is also OBD-I so there's not much more available. I would like to upgrade to OBD-II and EFI for better performance. That would cost a lot of money though.
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Warren

Currently 1965 220Sb, 2002 FORD Crown Vic Police Interceptor

Had 1965 220SEb, 1967 230S, 280SE 4.5, 300SE (W126), 420SEL

ENTER > = (HP RPN)

Not part of the in-crowd since 1952.

Last edited by wbain5280; 11-17-2004 at 10:54 AM. Reason: Add rpm and dilution
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  #13  
Old 11-17-2004, 10:39 AM
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Before I comment, I'd like to see the O2 content. This looks like the California developed acceleration simulation mode (ASM) test, and our reports list the O2 content, which is an important diagnostic tool.

Also, what is the odometer reading?

I don't know what is meant by "dilution". It might be defined on your test report. The web site for your state agency that administers the emission test program will probably have a definition and more information on how to iinterpret the report.

Duke

Last edited by Duke2.6; 11-17-2004 at 12:22 PM.
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  #14  
Old 11-17-2004, 01:16 PM
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There is no O2 reading on the test. From the Va. Dept of Environmental Quality, here is the definition of:

Dilution- This is a measurement of carbon monoxide and carbon dioxide in the exhaust stream. If the vehicle being tested is determined to have "invalid dilution," that could mean that the vehicle has an exhaust system leak, or some other problem that prevents a valid sample of exhaust emissions that must be repaired in order to be properly tested for emissions.

Odo reading 156032 miles, 6 cyl as well, M103, OBD-1.

http://www.deq.virginia.gov/mobile/mobfail.html

http://www.deq.virginia.gov/mobile/homepage.html
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Warren

Currently 1965 220Sb, 2002 FORD Crown Vic Police Interceptor

Had 1965 220SEb, 1967 230S, 280SE 4.5, 300SE (W126), 420SEL

ENTER > = (HP RPN)

Not part of the in-crowd since 1952.
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  #15  
Old 11-17-2004, 01:46 PM
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Your test results are different than the typical M103 readings in CA. M103s tend to be high on HC - close to or a little above the limit - on the 15 MPH test, but much lower relative to the limit on the 25 MPH test. I attribute this to the converter being relatively cold at the start of the 15 MPH test, which is why "conditioning" is important i.e., go to a drivethrough test station with a short line with the car thoroughly warmed up (at least 20 minute since the cold start) and keep the revs at 2000 with A/C or defroster on, so the compressor is placing load on the engine.

The 15 MPH test has a relatively higher load than the 25 MPH test and heats up the converter. The O2 content indicates how efficiently the converter is operating. If O2 content is zero, then the converter is operating at max oxidation efficiency - using all the available O2. Typically the O2 reading is a little higher at 15 MPH than 25, indicating that converter efficiency is higher on the second test, which is the 25 MPH test. O2 content is typically zero to 0.3 percent and anything above zero means that HC can be reduced if the converter is hotter.

The higher NOx in the 25 MPH test is inexplicable to me given that this test is done at lower relative load, and you can see that the stardard is a little lower than at 15 MPH. Given that your 15 MPH NOx is well below standard I cannot explain the high number at 25 MPH, but I would not discount test or measurment error. I've seen this before.

For example, my '91 MR2 was tested last year and the O2 content was 2 percent with passing scores on the pollutants that were well below standard. Such a high O2 reading on a O2 sensor car is virtually impossible unless there is a malfunction and none iwas indicated either by the OBD or test results. Prior test showed zero to 0.1 percent O2 with very low emissions.

Keep you test report and if you have previous test reports keep them all together or handy so you can look at trends, which are useful in diagnosing emission problems.

P.S. Ignition timing has a signficant impact on emissions. The M103 ignition system controls advance based on a combination of engine speed and load. Load is represented by manifold vacuum - higher vacuum is less load, and usually more advance via the vacuum advance system. Retarding the timing from normal will reduce peak flame front temperature, which reduces NOx generation and increases EGT, which will get the converter hotter, faster and reduce HC and CO.

One "trick" you can use if your M103 is on the ragged edge or marginally fails is to disable the vacuum advance by plugging the vacuum line to the EZL module. Also, there is a resistor module plugged into a pigtail and the value affects the rate of advance with engine revs. There have been a number of discussions on this and IIRC it you short the plug (zero resistance), the rate of ignition advance will be slower, which will retard the timing for any speed load condition relative to the OE timing map.

Since the 25 MPH test is done at lower relative load, there would probably be more ignition advance due to the vacuum advance.

The fact that engine revs are the same indicates that the 15 MPH test was second gear and the 25 MPH test was in thrid. Some ignition advance systems also use transmission gear to determine advance, sometimes by locking out vacuum advance in the lower gears. I don't know if this is the case with the M103.

Duke


Last edited by Duke2.6; 11-17-2004 at 02:01 PM.
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