wunfstgsr

Hello i went to smog my 96 Honda Civic DX Today and failed with high HC and high CO, the guy said its prolly running rich. The engine is stock and runs real strong, i replaced the header/cat since the original one had a crack. everyhing is stock and has new plugs and air filter. Can anyone give me any tips or what to try to help pass thanks. Only thing i can think of is maybe timing is off so i need to check that asap..

mk378

Yes check the timing. Make sure fuel pressure compensation hose is connected from the fuel pressure regulator to the intake manifold. Remove spark plugs and see if one looks fouled because that cylinder is richer than the others. Check ECT and IAT sensors with ohm meter versus service manual chart of resistance vs. temperature. If temperature readings are wrong (though not enough to throw a code) the mixture will be off.

wunfstgsr

Well I checked timing and it was off so me and my freind adjusted the timing so the middle line lines up with the pointer on the timing cover. I also replaced the o2 sensor on the bottom of the cat because the one on there had a short harness and was stretched tight to reach the plug from the engine harness. After driving the power feels much better and improved and seems I'm getting better mpg. I'm gonna replace the cap and rotor and wires and try smoging it again..

Former User

O2 levels look high. You also may have an exhaust leak in the header.

wunfstgsr

I replaced the header/cat with a real good condition one. The one I had was cracked real bad so I found one that was in near mint condition as far as the cast metal runners that are prone to cracks.

Former User

Before or after the smog test?

wunfstgsr

Before the smog test, I drove on it for a few hundred miles and on the smog day I drove it for a hour or so to make sure it was nice and hot when I got there.

wunfstgsr

Man it was the best thing I did for that engine. The engine was replaced about a few weaks prior to my smog, the original Y7 engine spun a rod bearing so I replaced it with 2000 spec Y7 engine from the junk yard. The engine burns no oil at all and is very healthy and strong. The header that was on there was cracked real bad and sounded like a darn truck but after putting the new header I baught it sounded very good and felt better driving. I'm only using the lower o2 sensor from my old header the one on top that came with the header looks new.

Former User

The O2 levels seen in the emissions sheet suggest an exhaust leak.

mk378

Idle the engine and block the tailpipe with a rag. Exhaust leaks will make a hissing sound. If there is a leak before the first O2 sensor such as the manifold gasket or a cracked manifold, it will likely cause smog problems.

The first O2 sensor at the top of the cat controls the fuel mixture. The second one, at the bottom, is only there to check cat performance and throw a P0420 if it is low.

wunfstgsr

Ok I'll check for leaks in the manifold but I looked it over very well before i stalled it!

wunfstgsr

update,

i checked my timing and it was way off so we adjusted it with the gun and the engine runs 10x better and lot of power was restored but the next weak i got cell for the bank 1 o2 sensor for slow responce so i replaced the sensor and still got the code after a few hundred miles so i looked everything over and realized the o2 sensor plugs were switched so im gonna try and smog it again in a day or two, so far the code has not come back.

wunfstgsr

So i smogged the civic again and it passed Emissions but failed the functional test. 2 incomplete monitors for catylist and 02 sensor. It did much better on the emissions though i just have to wait till the ecu clears them and sets them for ready and ill go back and pay them $8 and its done. I did wait till my gas was empty and pumped 91 instead of 87 but not sure if it made a diffrence or not.