I just went down to the get my car smog checked. It passed, but just barely at the 15 MPH test. It did pretty close to average at the 25 MPH test. Here are the test results.

15 MPH
%CO2=15.0
%02=.1
HC=32 (MAX=56 AVG=9)
CO=.34 (MAX=.51 AVG=.02)
NO=430 (MAX=443 AVG=57)

25 MPH
%CO2=15.2
%02=0
HC=10 (MAX=40 AVG=7)
CO=.09 (MAX=.49 AVG=.03)
NO=45 (MAX=730 AVG=45)

Every result was vastly different between the 15 mph and the 25 mph test. But the NOx test was the one that had a HUGE! difference! I have read things about the possibility of a lean mixture, carbon deposits, low compression, catalytic converters, EGR valves that need to be cleaned, vacuum lines that may be leaking raw gas into the engine, BUT WHERE DO I START?. I understand the car is suppose to be under a greater load at 15 MPH, but what does that indicate about what could be the problem?

I take great care of my car. I've owned it since it was new. I've changed the oil every 3K-5K miles. I change the plugs and filters on a regular basis. It's had several tune-ups in it's 160K miles. I'd like to head this off at the pass before it gets to be a problem.

ANY HELP IS GREATLY APPRECIATED!!!!

Thanks!

Richard

 

See my post at following link:

https://honda-tech.com/zerothread?id=1011034

One problem I've noted w/ the test is the low rpm of the low speed test may prevent any EGR activity, hence the NOx will probably be much higher. My 94 EX was higher at 15 mph after the cleanup than before, but the rpm of the test was ~100 rpm lower than the first test. I would ask that the "15 mph" setting be on the high side of 15 rather than low. Speedometer calibration might be an issue also.

Cleaning the EGR manifold and ports may help, but your performance at 25 mph shows good, so manifold may not be the problem.

Make sure base timing is set correctly. Incorrect timing setting can cause emission problems.

Also make sure your car is fully warmed and has had a brisk drive before taking it in for testing.

good luck

 

Thanks! I have noticed the speedometer is 2-4 mph too fast. So, when they thought they were doing 15, they were probably only doing about 12 or 13 mph. Maybe I'll look into getting my speedo calibrated (Is that possible?) for next time. I'll also check the timing and make sure it's all within specs.

Thanks again!

 

they dont go by the speed on ur speedo, they go by the speed of the dyno that they are testing it on which is pretty accurate