I have a 92 v6 LE camry with 230,000 miles which recently failed the NOx emissions test. The limit was 1167, I came in at 1637 (ppm). It easily passed the HC and CO tests. Had the spark plugs, air filter, pcv valve, distributer cap, fuel filter, and ignition wires replaced about 14,000 miles ago. Question is, what easy fixes can I do to pass? I don't want to put a lot of money into this car, considering the high mileage. Will new filters, spark plugs, and maybe a fuel additive w/ acetone be enough to get me a pass?

 

You could try to clean the injectors. A lot of shops have injector cleaner machines that flush the systems (i sure there is a more accurate name for this machine) This, of course, is not free. I have a 93 v6 with 230k aswell and I had my injectors cleaned and it came in lower that the emissions test from 2 years before. If the injectors are not vaporising the fuel properly, these levels will be higher.

Also, i have to ask the question that predates history. Is the check engine light on? Could be a bad 02 sensor if it is.

This car could merrily last for another 70K easy and I would not be concerned with putting money into it.

Toyomoho is going to give you a better answer than me but I hope I was some help!!

 

High N0x is the result of high combustion temps or failed catalytic converter.

Engine running too hot, high coolant temps.

Incorrect engine timing, this is the timing set with the timing light.

Intake manifold air leaks causing the engine to run lean.

EGR value not working right or plugged with carbon. The EGR valve recycles a portion of exhaust back into the intake to lower combustion temps.

Slow responding or failed 02 sensor(s).

Failed catalytic converter.

Was the car tested at both idle and a higher RPM (around 2500)? If so what were the NOx readings at both RPM's.

 

I have a 1993 v6 le the 319000 miles . On my first test, everything failed and I had a tune up. After the tune up, only the nox failed but, failed at a higher number than the first test. Next I had the egr valve replaced and the nox stayed around 1263. I've been told I should just have the catalytic convertor replaced and it will solve everything. Does anyone have any experience with this?

 

What are the emissions numbers for all gases checked?

 

Before the tuneup
25/25 allowed 50/15 allowed
HCppm 213 117 187 120
CO% 3.56 .65 2.97 0.67
NOppm 993 821 1050 907

After tuneup and EGR
25/25 allowed 50/15 allowed
HCppm 103 117 093 120
CO% .30 0.65 0.25 0.67
NOppm 1247 821 1510 907

 

EGR is off at idle but opens at RPM. Does the EGR valve open at RPM?

You may need a new CAT/

 

Well, after replacing the cat, it passed the test. But, I ran into a person at emissions testing that told me that I wasted my money on the egr and cat. They tested my vacuum lines and said they were clogged. They said the new cat would allow me to pass but, it's making the cat work harder.

 

replacing the CAT will do you good but cleaning the injectors and the vacuum lines will do you better for the engine.

 

Replace the 02 sensor- that is likely the culprit. A lazy or biased sensor can greatly affect catalytic converter efficiency.

JJ