i recently did the emissions test here in ontario and my car got a
fail grade due to high NOx leves. I’ve already changed the EGR valve
for a new one already. i was wondering if anyone else had some good
tips for fixing an NOx emissions problem with these cars? or if
anyone’s had experience with this problem and knows which sensors
might need chaning/any other probable causes to this problem. as the
subject says its a ’93 ford Taurus 6 cylinder, 3.0L GL. any tips would
be appreciated =)
Posted at author's request, using moderated
try the oxygen sensor. should be in the exhaust pipe somewhere.
> i recently did the emissions test here in ontario and my car
> got a fail grade due to high NOx leves. I've already changed
> the EGR valve for a new one already. i was wondering if anyone
> else had some good tips for fixing an NOx emissions problem
> with these cars? or if anyone's had experience with this
> problem and knows which sensors might need chaning/any other
> probable causes to this problem. as the subject says its a '93
> ford Taurus 6 cylinder, 3.0L GL. any tips would be appreciated
"janka" wrote: (1993 Ford Taurus 6 cyl 3.0L GL.)
Here in Ontario my car failed its emissions test due to a
high NOx level. I’ve changed the EGR valve. Does
anyone have some tips for fixing a NOx problem? Which
sensors might need changing/any other probable causes?
Hi NOx indicates air/fuel mixture too lean. The EGR
valve richens the mixture, so the new valve may solve
the problem. The most likely other source of excess
air is a vacuum leak. Sometimes a defective oxygen
sensor will fail to trigger the EGR valve.
Only one thing causes NOX - high temps in the combustion chamber.
Several things can contribute to this.
High operating temps or lack of EGR are the most common.
Extreme lean mixture can contribute to high operating temps. So can a
bad rad, bad water pump, bad fan. etc.
Almost all engines will produce SOME NOX under normal conditions -
some more than others - so a reducing bed catalyst is used to clean up
If the reducing bed is dead, high NOX can result. The catalyst CAN
still be working for CO/hc reduction (which is an oxidizing
catalyst)and yet fail NOX.
If you have high NOX, verify the EGR is working, verify operting
temperatures, check for oxygen leaks, and replace the converter if
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