[DML] Re: Failed Emissions

[Calducati@xxxx]

Mark Wrote:

<< 
After many months of reading and learning of trouble areas and repairs on 
the 
DMC, it is now my turn so here goes. I just took the "D" for its emission 
test here in Arizona and failed the portion that deals with oxides of 
nitrogen (NOX). The brochure provided to me by the testing described what 
to 
look for:
1) Possible EGR system malfunction
2) Abnormal engine operating temperature (car has run consistently within 
normal temperature ranges)
3) Air management system
4) Lean air/fuel mixture
5) Catalytic converter efficiency
6) Over-advanced off-idle timing

The question I have is out of these possible causes, which is the most 
likely 
to cause this failure and have checked first, then second, etc.? I'm sure 
this has occured to someone else and any assistance is greatly appreciated. 
FYI, the car is a 1983 automatic with 2,760 miles. Thanks again.

Mark,

1) First, there is no EGR valve system on the DeLorean, so skip this 
information. 

2) Based on the cooling system gauge reading normally for you, I would skip 
looking for a hot spot in the cylinder head or cylinders.

3) There is no air management system to speak of, so skip this.

4) Lean/Air fuel mixture is a good possibility. 

5) With only 2,000 miles on the car, it is really doubtful that there is a 
catalytic convertor problem. The car would have to be running rough or 
poorly to create a problem in this area considering the low mileage.

6) Timing is a major factor in high NOX emissions. I can not speak for 
Arizona's smog inspection procedures, but here in California we have to check 
the timing during the smog test, so I would have to assume that this was also 
done and the timing is within specifications.

So what is causing your failure? Please provide me with the reading of NOx, 
HC, CO, and O2 if you can. Did you fail at the idle portion of the test or 
the 2500 rpm level? Was the car fully warmed up before the test was 
performed? Are you having any other problems?

I will provide what help I can without seeing the car. 

Quick background: I am a licensed Smog Technician here in California. I am 
also a certified ASE Master Automobile Technician. I do not work on 
Delorean's or own one. I am just a fan of the car. My dream would be to own 
one some day, when all of the planets align in my favor.

I hope I can help.


David

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