1993 Toyota Corolla Q&A
1993 Toyota Corolla Question: failed emissions for NOx
Most NOx failures are due to faulty egr systems. It would be a good idea to have your egr system thoroughly inspected and repaired as necessary. Also, don't forget to double check the ignition timing - if the timing is off that can affect NOx also. If the egr system and timing are OK then the problem becomes more difficult. NOx gases are formed due to excess heat in the combustion chamber. Carbon build up in the cylinders and cooling system issues are just two examples of item which can cause high NOx readings. - Russ
Russ is correct. I do believe a complete FUEL INJECTION SERVICE will get your numbers back. - backyard tech
The EGR System tends to get restricted or blocked with carbon after 100,000- 125,000 miles which will cause an emissions test failure for NOX. If the EGR system is equipped with an EGR temperat...
my corolla is a 1998 so it did not come with a egr valve smog fail shows NO reading at 15 mph measures 1646 max is 477 at 25mph measures 1556 max is 746 and HC reading at 15 mph is 91 max is 64 at ...
Can I assume that if I replace plugs and wires That this will do the trick ? Or should I swap-out O2 sensor too?
At 25 MPH NOX was 346. What caused high NOX at low speed? VIR indicates that EGR is NA. What could be the cause of this failure? What is the best solution?