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Automotive/failed Ontario Canada emissions test

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Expert: - 11/4/2007


Question
Hi Ernie. My 1992 plymouth sundance duster 3.0L V-6 failed the emissions test. The only section that failed was the 40km/h drive test NO ppm limit 505 reading 666.  Tried the test a second time after letting the car warm up for a longer time before the test...2nd reading was 777. Mechanics are suggesting the diagnostics test, there is not an EGR valve on this model. So, a possibility is the O2 sensor, timing, or an expensive cat. There is a Repair cost limit of $450.00  I've changed the oil, air& oil filter, PCV valve, ran 3/4 of a liter methyl hydrate through it before been tested.  Any ideas to bring that reading down without spending too much money?  Kelley Blue Book value of this vehicle is $495.00  Thanks for any input, Joe.

Answer
NOx is the one thing that goes up with combustion efficiency, that is, as the CO and HC values approach the ideal values indicating stoichiometric (14.7:1 air:fuel ratio) combustion, the NOx values increase sharply.  These peak at about 16 to 16.5 to 1, which definitely is lean.

With a carbureted vehicle, you could probably bring down NOx values that are not too far over the limit by slightly enriching the fuel via the idle bleeds (which DO play a role still in the lower end of the driving range), provided that you do not let the CO and HC values get too close to their limits.

With an ECU-controlled vehicle, if your CO readings are good (very low), this is a good indicator of proper oxygen sensor performance, and I would leave any concerns as to the sensor at that.

Timing is an issue with any engine, so it would be worth verifying that the initial timing is as it should be, and that the advance is also within specifications.

Ultimately, the purpose of the catalytic convertor is specifically to clean up exhaust residues that cannot otherwise be eliminated by combustion controls; largely, its purpose is to handle the NOx limits.  You may well have to consider the catalyst's replacement.

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Ernest (Ernie) Kenward

Expertise

The challenges I most enjoy are thoughtful technical questions of a trouble-shooting nature in both electrical, power electronic and mechanical systems, mainly automotive but also machine control and small-machine PLC applications. Please note, however, that I am NOT a walking shop manual! I DO, however, make it a point to have those manuals and other service literature for those vehicles I DO own, and highly recommend that anyone serious about maintenance or modification of their vehicles do the same; MOST of your answers WILL be found there. For that matter, I do NOT go out of my way to acquire shop manuals for any vehicle I do NOT own! That being the case, any general query to me along the lines of "What is the meaning of this code read from the ECU of my 2015 XYZ?" or "Where is the fuse for the windshield washer pump found?" (try your car's electrical distribution panel for a start!) will not go far. What I do offer is a pretty good collection of literature, insights and hands-on experience with 1950s to 1980's Ford products (plus a developing database of information and practice with the Mercedes diesel cars), along with an engineering perspective and the ability to design and implement custom control, electrical and mechanical subsystems for vehicles. For that reason, I am happy to make my thoughts and efforts available to those who are of like mind and/or are seriously making a point of learning about their vehicles. Use the Opportunity to Learn!

Experience

A key skill in my work and hobby pursuits both is STRATEGIC TROUBLESHOOTING. I am a senior instructor in Electrical Engineering Technology at a leading Canadian polytechnic, my areas being Electrical Power and Industrial Control, electrical and electronics design and manufacturing, and AutoCAD and related CAD/CAE software - plus equipment problem-solving and new equipment design and prototyping. Hobby-wise, I have 30-plus years of experience in auto restoration, mostly in electrical and mechanical systems. Ongoing projects include a 1959 Edsel Corsair, my 1978 Ford E250 class-B motorhome conversion, and the care and upkeep of my Mercedes 300CD. My vehicles become engineering test beds for electrical and mechanical upgrades as ideas present themselves. This includes the design and production of circuit boards to restore or enhance features for which no OEM replacement parts are obtainable, or where better specifications or reliability can be had via newer concepts. Regarding the E250 RV conversion, I designed and continue to revise a custom power distribution system, managed by a Programmable Controller (PLC); this has made most revisions as easy as uploading new firmware as I develop it. The "mini" PLC is a powerful device for custom automotive control systems. One good example (there are many) would be the Moeller "Easy Relay"; these offer a wealth of control, monitoring and variable-and-status display options for such projects. A good example project which has worked well is that one for my RV noted above, which has been on the job - revised in firmware only - for a decade now. It is a load management and charging control system to avoid the sulfation-induced early failure that often befalls deep-cycle batteries used in RV power applications. The battery installed in 2003 lasted long enough to more tnan pay for the PLC that contributed to its longer life ... and the PLC will be there for the next battery as well!

Organizations
IEEE - senior member ... past WCC Student Activities; SME - senior member ... past chair, greater Vancouver chapter chair 318; Edsel Owners' Club - have served in various capacities on chapter executive during seventies; have been Power and Driveline resource on the Edsel Owners' Club "E-team" for more than a decade.

Education/Credentials
Graduate of UBC

Awards and Honors
Certificates of appreciation from IEEE and SME for work in student and chapter activities

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