I have a '93 Integra RS Auto. 300,000 kilmetres (about 190,000 miles). Failing emissions test with High Nox. (3 times limit). Has newer oem egr valve, brand new aftermarket catalytic, recent oil change, newer air filter, PCV valve, always well maintained. Spark plugs are newer. It used pass well and recently fails dramatically. Seem like it woudl be one specific thing. Would the Main Relay have anything do with this? I replaced the original myself a couple years ago (maybe around the time it started to fail) and I noticed that the relay wasn't EXACTLY the same as the orig (it was a different colour)... I'm just taking a wild guess that maybe it's a electronic issue, and perhaps related to the relay. If not that, and given everything else that has been done, anything you can suggest?
Country: CanadaMake: AcuraModel: Integra RSYear: 1993Engine: 4 cyl 1.8 L
Hello!Did you still need help?HOw does the engine run?Did you warm up the vehicle and light the converter off before taking the emissions test?
HI there, engine runs very well & strong. Not sure what you mean about the converter...you mean give the car a good run before the test?
YES... thats correct. Did you drive the vehicle for a long time before the test?
20 - 25 minutes.
Ok.. that should be ok.. but you could bring the RPM's up a bit right before you get to the testing station. The brick inside the converter needs to light off. It needs to get HOT in order to work efficiently. The hotter it the brick inside gets, the cleaner it will get the emissions coming out of the tail pipe. Another thing would be ignition timing. If you have not checked ignition timing, this should be checked as this could very well cause high nox readings. The main relay will not cause high NOX readings. It will not affect the emissions in any way. All it does is provide power to certain components of the vehicle to allow it to start and run.I hope this helps! Please let me know if you have any further questions!
Thanks, XXXXX XXXXX not involved... i thought e.g. because it controls some things, that perhaps it controls a sensor (o2?) that impacts emissions and since it isn't exactly same as orig, maybe it's "telling" a component to act improperly... I'm not a mechanic so that was just a broad guess. The timing belt was just replaced, and assuming the mechanic set it right that wouldn't be the cause (it failed high NOx 2 years ago as well... it's way over limit...seems like even if I drove it for hours on the highway, it still wouldn't pass. If you have any other ideas, please let me know - I believe just about everything that could be done, has been - process of elimination and yet still way over... the other readings are very much under limit, just the Nox. car is just "OLD" !?
Hello!If the timing belt was off a tooth or two, it could affect the nox. But if the timing belt installation was done correctly and the timing belt has not jumped time since then it should not be an issue.In rare cases, the engine can and run lean because of a sensor like the o2 sensor and engine coolant temp sensor and cause the NOX readings to go up.Plugged or restricted fuel injectors could also cause high nox readings because it is causing the engine to run lean.Just be absolutely sure that the EGR ports are NOT plugged up. This would restrict the exhaust gas flow going into the cylinders thus causing the NOX numbers to be higher than normalAlso, don't forget about the ignition timing.Please don't forget to rate my answer as "Great Service" so I get credit for assisting you today. Best RegardsAmedee
ASE MASTER TECHNICIAN ADVANCED LEVEL SPECIALIST