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Failed Emissions test on high NO (NOx), any ideas?

Gillbot

Gillbot

Lifer
Don't laugh, it's my daily driver.... 1995 Ford Aspire, 1.3L I4 engine, 5 speed manual trans on the floor.

Failed Emissions here in Ohio on high NO (NOx). I know this is usually a sign of running lean, High load, failing catalytic converter and many other things but it barely failed. 1600ppm reading and 1400ppm is allowable. I think alot of it had to do with the long idle wait time in line at the testing facility as well as the leak in the exhaust before the converter.

Things corrected:
Found a leak pre catalytic converter and made repair welds
Changed the O2 sensor (Had loads of white scaly deposits on it)
Cleaned and regapped the plugs (looked in pretty good shape so they went back in)
Cleaned MAF with electronic cleaner/degreaser
Changed PCV Valve
Wires tested ok, left them alone

Idles ok still but seems to have a slight shudder after the car is hot. O2 sensor change made no difference in idle or driving quality. I think it may be overheating slightly so I may change the thermostat or wire the fan on with the ingition until after the test. Also may try running a higher octane to see if there is pre-ignition in the motor causing the shudder after the car gets hot.

Any ideas on other things I can do before I go test again?
 
I'll bet the exhaust leak fixed it.

If not, fix the thermostat and then check the EGR system. If your EGR is not working, it'll cause high cylinder temps (which is a DIRECT cause of NOx.)

 
The EGR solenoids are operating unless the lines are plugged.

I added STP fuel treatment a few times now to help clean it out and I plan on a motor flush and oil change soon as well.
 
man just go retest, you dont HAVE to get to 14000 i think its just decrease ur score by so much, or thats what i think you have to do.

MIKE
 
It MUST pass below 1400ppm on NOx or it will fail test 2 and my plates cannot be renewed w/o repairs by a certified facility, which = $$$
 
Maybe a new air filter...could also be that the timing is a wee bit off.

If there is preignition when it gets hot, higher octane should help a bit, and so should a new oil change, as the new oil should help the engine cool a few.

If you can get it, try putting some RedLine water wetter in the coolant when you change it. It'll also help kit the car cooler.
 
Originally posted by: Gillbot
The EGR solenoids are operating unless the lines are plugged.

I added STP fuel treatment a few times now to help clean it out and I plan on a motor flush and oil change soon as well.
Click to expand...
I don't recall if this is physically possible on an Aspire...

But to check the EGR passages, lift up on the diaphragm of the EGR valve when the engine is idling. If it is clear, the engine will run really bad, or most likely stall.

Like I said... Run it through again. It'll probably pass since the exhaust leak was fixed.

 
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