1989 300E - 36,000 miles

I currently reside in Canada and am obligated to submit to an emissions test every two years. Upon having the vehicle tested today, it failed the HC and CO test miserably.

The testing facility ran the vehicle so that the engine would be warm during the testing period. The car was not run on a dynometer.

The test was segmented into two components - 2500 RPM and IDLE RPM
The results were as follows:

2500 RPM

HC ppm Limit 200 Reading 24 PASS
Co% Limit 1.00 Reading .04 PASS


IDLE RPM

HC ppm Limit 200 Reading 264 FAILED
Co% Limit 1.00 Reading 5.13 FAILED

I am suprised that it ran so well under load but failed so poorly during the idle component.


Additionally, another peculiar trait that has manifested occurs when I release the accelerator pedal and coast (ie. approaching a corner ) under 2000 RPM while driving. The engine surges between 1000 and then back to 2000 RPM for 3 times - then the surging stops. This happens during cold or hot conditions.

I wondered if there was a possible connection. Other than that the car idles at 700-750 RPM and drives well.

As mentioned in a previous post, when I bought the car, I encountered some starting problems and elevated Nox readings which resulted in failed emissions test. After replacing plugs, rotors, cap and cleaning the injectors, the ECU was finally replaced (used unit). The car passed the emissions test.

Any assistance would be appreciated as it has been most frustrating.

Thank you.

Keen

you need to make sure that all is well with the engine.
then i would suspect that your pre cats or catalytic converter
is/are bad.
very common failure here in calif with those figures.

george

I suggest you read the following article.

http://www.peachparts.com/Wikka/M103VacuumLeak

If you ca do some repairs yourself all the better. Why was the car not run on a chassis dyno?

__________________
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 is usually called the "two-speed idle test" and is the simplest field emission test. HC and CO are measured at idle and 2500 RPM, no load. It is deemed adequate for areas that don't have significant air quality problems. Areas that don't meet ambient air quality standards in the USA are required to do a road load test, which allows the measurement of NOx since significant NOx is only produced when the engine is under load.

Your 2500 RPM numbers indicate all is well, but the idle mixture is very rich as indicated by the high CO.

M103s often show high emissions due to insufficient catalyst temperature, and the temperature required for the catalyst to promote reaction increases with age, but if the engine was tested at 2500, then immediately tested at idle, I don't think catalyst temperature is an issue in this case.

It's also my hunch that the surging you report is related to the emission problem.

Checking for vacuum leaks is a good starting point. Also check microswitch and throttle position switch function. Then you should check the duty cycle. If someone has diddled with the basic mixture screw, the Lambda system could be operating at the limit of its control authority.

Familiarize yourself with following link and the links contained therein.

http://www.peachparts.com/shopforum/tech-help/117048-successful-ca-asm-emission-test-ke-fuel-system.html#post833484

Search on "microswitch" and "TPS" if you're not familiar with those components. The above link also has links to the shop manual data that you can view or download.

One needs to understand the somewhat complicated K-Jetronic system and learn proper test and troubleshooting procedures.

There aren't any silver bullets. You need to do some serious research and educate yourself, but my hunch is that the problem is not serious and will not be expensive to repair if you do it yourself, but it may be time consuming.

Duke

Many thanks to all who have responded.

Based on some of the comments, would this issue be resolved by re-adjusting the idle mixture which would appear to be running too rich?

Additionally, I have detected a minor stumble during initial start up of the car. Then the engine regains its composure and idles between 700-750RPMs.

Regards,

Keen

Possibly. That's why I recommended checking the duty cycle. That is the way you set the mixture. In fact, it is the ONLY way to set the mixture without screwing it up.

Duke

Duke:

I have arranged for a emissions shop to have a look at the car to confirm if the idle is set correctly and also to run the test again.

Will post the result. Many thanks for your insightful responses.

Regards,

Keen

I hope you ascertained that they understand how to check (and adjust if necessary) the duty cycle as explained on the Landiss site and in the service information at the Braingears site.

I don't think a lot of professional shops understand this procedure.

Followups are always appreciated by all.

Duke