my mitsubishi 93 expo lrv 1.8 engine failed emissions again. i am a backyard mechanic. it failed in NOX . the limit is 2.50 and and i am getting 2.57. everything else is passing fine , like HC 0.56, limit 1.00, and CO gets 5.19 the limit is 12.00. It have 225.000 miles on it, but I always been taking of my car, runs just fine. Somebody told me that in order to knock out a little the NOX and finally PASS i must retard the timing 1 or 2 degrees. the catalytic converter is fairly new, less than 5000 miles on it, an this car DOESN’T HAVE egr valve, because is arizona model. I really like this car and planning to keep it forever. the OX sensor is almost new. i replaced it last time i passed emissions. I really HATE emissions. this car is a lot cleaner than the car we used to drive 40 years ago, and i am not planning to replace the engine because is running good. what am i supposed to do??? thank you.
I know there are chemical products that are supposed to help ypu pass emissions, you might try one of them. Retarding timing 2 degrees might drop the combustion pressure and temp enough to to pass. Good luck. In my state pre- obdII cars aren’t emissions tested except visually.
Are you certain this car does not have an EGR valve? A parts house listing shows one as being available. My daughter has owned 3 Mitsubishis from '91 up and they all had EGR systems.
I’m not familiar with a so-called Arizona model. In '93 there should be 49 state Federal cars and a California model by itself.
I think EGR valve are a federal mandate on all cars. If you are not sure about this, make sure, as the EGR is responsible the primarly control of NO emissions. It would be very common to have one fail at this mileage. And they are generally not expensive to replace. You other specs look like the car is running well and well maintained. I don’t think the cat is related to NO emissions. It’s only for HC and CO. Double check the EGR issue I guess.
I am 100percent my car never had a egr valve. It is in all the books and for whatever reason they sold this mitsubishi model whitout an egr valve, but the california model came with that valve . You guys can check in any oficial book and find out that this is true. I dont know why, but I am glad I have one less piece to worry about it
Carbon buildup in the combustion chambers?
I continue to be doubtful your car has no EGR valve. Can you provide a link supporting that your car has no EGR valve?
This is what I could find with a little Googling for a 93 LRV 1.8 SOHC 16 valve. If it is accurate, you may be confusing the EGR valve with the EGR Temp sensor (that part is only used in Calif apparently.) Take a look-see, maybe you can in fact spot the EGR valve. Do you see where you put the oil in? The EGR valve seems to be located to the left of that (if you are looking at the engine from the front of the car), near the left hand (passenger) side of the valve cover. There appears to be an EGR solenoid control valve too, maybe bolted to the firewall, to the right of the oil filler cap (again, when looking from the front of the car.)
Note: You can use RockAuto’s website to see what your car’s EGR valve looks like for reference.
Emissions devices:
Catalytic Converter
EGR Valve
EGR Temperature Sensor*
Oxygen Sensor
PCV Valve