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.

__________________
Regards

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.

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.

__________________
2007 C 230 Sport.

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.

__________________
Regards

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.

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.

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

__________________
Auto Zentral Ltd.

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

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.

__________________
Regards

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.

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

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

__________________
Regards

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.

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

are excellent for the car, don't overanalyze it. Your Co and HC are very good. Run some diesel fuel injector cleaner in there as I suggested and see how it goes. The state of Virginia has actually made it harder on these cars, if you go back to your tests 2 and 4 years ago you'll probably see the NOX limit has been lowered meaning the car must perform better.

High NOX is not 700 or so. It may be for the state of virginia but isn't for an older car. I've been amazed by my own propensity, and that of many folks, to react to a number that is at or slightly above a state limit. The state limits are somewhat arbitrary and do not take into account age of the car, age of the catalytic converter, etc. I've studied the equations, relationships, etc between NoX, oxygen, etc etc etc. I can tell you that you are on the path to hell here if you overdo it-- I did that. If you sense the car is UNDERpowered then you have a reason to go in there and determine if the cat is clogged, etc. Of course check for vacuum leaks but I don't see that as a likely cause here per my other post, but what do any of us know really in the end since we guess with an esoteric thing like NOX value.

If you are experiencing less power with the car, then you probably have a clogged cat. I don't know if your car has pre-cats, but they can clog. If your power is good and everything else is good, run some cleaner in there and leave it alone. Trust me, you're on the way to a very big litany of stuff that may result in a better car in the end (maybe more power) but great expense as every mechanic or you go in there and try to guess the thing out. If it really bothers you, other than cheap and easy things you can do, the other thing is to put a Miller cat AND pre-cats on there costing you $1200 to $1500 for someone else to do it or I think about $600 parts plus whatever labor you can find-- that's a quote for another MB (mine).

It well could be the passaged for exhaust gas recirculation are partially or nearly completely closed off(plugged). Not uncommon, particularly on higher mileage cars. Some shops even clean them out every 30K service. Easy to use a 'spedometer cable' as a snake drill in a variable speed drill, and dribble carb cleaner down the spinning cable as you feed it in.