My '87 with a serious NOx emissions problem passed smog yesterday. Thanks to those who offered suggestions and help...

( Original thread: https://honda-tech.com/zerothread?id=856715 )


Here were the original results:

15mph (1870 rpm):
%CO2 - 13.4
%O2 - 1.6
HC(PPM) - MAX: 127 - MEAS: 14
CO% - MAX: .79 - MEAS: .01
NOx(PPM) - MAX: 825 - MEAS: 1944

25mph (1965 rpm):
%CO2 - 13.6
%O2 - 1.4
HC(PPM) - MAX: 101 - MEAS: 10
CO% - MAX: .68 - MEAS: .01
NOx(PPM) - MAX: 764 - MEAS: 1762


After extensive testing I determined the emissions controls were all functioning properly so I decide to take another approach. Even though much of the following was recently replaced, I performed the following prior to the final test:

New plug wires.
New NGK plugs gapped to max gap value of 1.1mm.
New rotor and cap.
Changed oil to 20/50.
Added STP in case valve guide seals were leaking (original seals).
Added 1 can of Berryman's B12 at 1/4 tank and ran tank almost empty.
Added another can of B12, added fuel to 1/3 tank, and ran it to almost empty.
Added 2oz of Blue Sky 3-in-1 fuel conditioner, added 91 octane gas to 1/2 tank.
( http://www.blueskycleanair.com )
Drove another 120 miles over the next three days and punched it hard at times to help blow out the carbon deposits.
Set the idle to the high side and set the timing to just above 13 degrees BTDC.

I assumed the open gaps on the plugs, retarded timing, and high octane fuel might result in higher HC and CO levels, but my real problem was NOx and I needed cooler combustion chamber temperatures. In any case, here are the final results:

15mph (1865 rpm):
%CO2 - 14.6
%O2 - 0.1
HC(PPM) - MAX: 127 - MEAS: 31
CO% - MAX: .79 - MEAS: .21
NOx(PPM) - MAX: 825 - MEAS: 28

25mph (1985 rpm):
%CO2 - 14.5
%O2 - 0.1
HC(PPM) - MAX: 101 - MEAS: 25
CO% - MAX: .68 - MEAS: .17
NOx(PPM) - MAX: 764 - MEAS: 1


Man, talk about reducing NOx emissions!!!

BTW, both tests were done by the same tech on the same dynamometer.

 

nice job....i like how your O2 output went waaaaaaaaay down on both low & high speed testing.

You could probably advance your timing again for a bit more power & fuel economy.

congrats! I'm sure your tired o' car-**** right now!!

 

I didn't mention it, but when I retested my idle and timing today they had mysteriously changed where the idle had gone from 750 to 800, and the timing was now at 17 degrees BTDC. Weird...