[DML] Re: Failed emissions: NOx

["Harold McElraft" <hmcelraft@xxxxxxx>]

NJ - If the machine was not hooked up correctly or not calibrated 
correctly you could get an incorrect reading. Assuming the machine 
was correct - high NO could be caused by a sticky injector throttle 
plate, stopped up injectors and even a clogged fuel filter, or stuck 
frequency valve. High NO can be from a leaned fuel condition. A 
failed O2 sensor usually results in a defaulted rich condition, so I 
would not automatically go for the O2 sensor. Vacuum leaks at the 
injector seals might do it or a vacuum leak at the idle tube port on 
the underside of the intake manifold might cause a lean condition. A 
bad Cat? Maybe - how many miles? Over 50,000? Has it ever been 
overheated for a long time? Is it clogged and choking the engine 
(the usual condition resulting in high NO)?

I would check ALL the seals at the injectors and idle tube and 
electrical connections around the Lambda, the frequency valve, etc. 
Clean them and be sure of good connections. Then, get a can of 
Marvel Mystery Oil and run a tank of gas with at least the 
recommended concentration on the can. This stuff has a great solvent 
in it that cleans fuel systems like nothing else, especially when 
warm. The Bosch K-Jetronic is a recirculating system which is 
perfect for this type of cleaning. It can clean the fuel system like 
new and NOT harm any seals or other stuff. I have used it for 20 
years. Last year, 2003, in NJ, my D at 53,000 passed with HC 21, 
CO .09, CO2 15.3, and NO 590. Ten years earlier in FL the same 
engine with existing tune-up that was fresh then, read HC 2, CO .02, 
CO2 15.0 and NO was not read. It has 36,000 miles on that last tune 
so I had to unplug the Lambda light :-). I have over 40,000 on the 
tune now. I attribute a lot of the clean condition to keeping the 
fuel system treated periodically with Marvel MO. It runs great - but 
I am getting ready to do the tune-up before the trip to PF in June. 
I am wondering if it will run as clean after the tune up.

Harold McElraft - 3354


--- In dmcnews@xxxxxxxxxxxxxxx, deloreanernst@xxxx wrote:
> Never had any emissions problems before with my D, but a week ago 
I failed for NOx.



To address comments privately to the moderating team, please address:
moderators@xxxxxxxxxxx

For more info on the list, tech articles, cars for sale see www.dmcnews.com

To search the archives or view files, log in at http://groups.yahoo.com/group/dmcnews 
Yahoo! Groups Links

<*> To visit your group on the web, go to:
     http://groups.yahoo.com/group/dmcnews/

<*> To unsubscribe from this group, send an email to:
     dmcnews-unsubscribe@xxxxxxxxxxxxxxx

<*> Your use of Yahoo! Groups is subject to:
     http://docs.yahoo.com/info/terms/