Failed the Emissions Test
Because of good ol ‘Rona, I’ve been driving my 95 Orvis edition around with a temp plate and no emissions since February. My tag is practically falling off at this point, so I decided to get ‘er done today! I went in for the emissions test, but failed, with a NOx reading .05 above the limit! -.-
After doing some research, I have found three possible causes of a High NOx reading (all other readings were fine):
-Coolant system not performing, resulting in a high combustion temperature
-Fuel/Air Mixture too lean
-Failed EGR valve
When I hopped back in after my beloved Orvis was run on the Dyno, I noticed the coolant temperature was three-quarters of the way up, the highest it has ever been. She has problems with heating up during idle, so I installed an auxiliary electric fan to supplement the mechanical one. Ironically, the fan is manually controlled, and wasn’t on, during the emissions test. Plausible cause number one.
I recently swapped out the PCV valve, which seemed to resolve a small vacuum leak and high idle. Not sure what else would contribute to a mixture problem, and despite the Check Engine Light sporadically coming on, it has not lit for several thousand miles.
The last time I ran the engine codes, it did indicate a problem with the EGR valve. I am ready to replace this, but cannot even *find* the dang thing! It has dual exhaust manifolds, and I assume the valve may be near the rear of the engine? Seems like a straightforward repair otherwise.
Any thoughts on what else could be my emissions problem? How can I find my EGR valve?
And by the way, I ran a full can of sea-foam through about two months ago. Hopefully that helped.
Cheers in advance!