Hi. Im new, so bear with me.

I have a 1997 Honda Civic HX, stick, with 209k on the clock.

I went for a smogcheck last month, results were..

Speed=15Mph
RPM=1562
%CO2=15.1
%O2=0.1
HC(PPM) Max=66 AVE=9 MEAS=10
CO(%) Max=0.57 AVE=0.02 MEAS=0.17
NO(PPM) Max=487 AVE=57 MEAS=1051 FAIL

Speed=25Mph
RPM=2422
%CO2=15.2
%O2=0.1
HC(PPM) Max=49 AVE=7 MEAS=6
CO(%) Max=0.55 AVE=0.03 MEAS=0.18
NO(PPM) Max=774 AVE=50 MEAS=553 PASS

I guess I should add, the car had been throwing a CEL off an on.. I think it was 66, the one about the cat not being as efficient as it should be. I had cleared the code before the test..

So, knowing that the code was the cat, I took off the exhaust manifold cover, and discovered the manifold was cracked. So I replaced it, and the cat, with the dorman part, 673-439 (CA Legal part) From there, I cleared the check engine light, and went to the ATM, and then straight to the smog check place. Drove maybe 3 miles total.. I left the car running while he was finishing up the guy infront of me.

Now my results are
Speed=15Mph
RPM=1561
%CO2=15.2
%O2=0.0
HC(PPM) Max=66 AVE=9 MEAS=13
CO(%) Max=0.57 AVE=.02 MEAS=0.05
NO(PPM) Max=487 AVE=57 MEAS=77 PASS

Speed=25Mph
RPM=2448
%CO2=15.1
%O2=0.1
HC(PPM) Max=49 AVE=7 MEAS=7
CO(%) Max=0.55 AVE=0.03 MEAS=0.01
NO(PPM) Max=774 AVE=50 MEAS=1042 FAIL

The guy at the smog check place said it was very strange, and that the low CO% numbers meant that the car was running very lean.

So, Any Ideas? Im at a loss at the moment.


Also, I dont think this has anything to do with it.. but... The car has always been hard to start, if it was low on gas.. the lower the gas level, the more cranking it takes to get it started. I have replaced the fuel filter recently, and it had no effect.

Thanks!

 

Vacuum leaks, ignition timing, running to hot.

 

maybe try running some injector cleaner through your engine. I always run seafoam about a week before smog, and usually don't have a problem passing. Also, new spark plugs, wires, distributer cap and rotor

 

Yes it's running very lean. Clean the injectors check the fuel pressure check for air leaks at the exhaust manifold (or did your new one crack already) maybe new O2 sensor. Timing is a good point, also check / clean out the EGR system if it has one, I think the HX and some California versions did.

Does it run good when you floor it, no signs of misfiring or starving for gas?

 

Yeah. The car runs fine. I mean, its a dog, always has been. I dont then the new exhaust manifold would be cracked within 3 mile of putting it on. Im gonna check the egr and injectors today.

 

Also you're supposed to drive about 20 miles after resetting the ECU to let it recalibrate itself for best emission performance.

 

Updated! so now, 3rd smog check.. failed again. Now both high and low speed tests.

the latest results are

Speed=15Mph
RPM=1556
%CO2=14.3
%O2=0.2
HC(PPM) Max=66 AVE=9 MEAS=17
CO(%) Max=0.57 AVE=.02 MEAS=0.01
NO(PPM) Max=487 AVE=57 MEAS=1384 FAIL

Speed=25Mph
RPM=2479
%CO2=14.3
%O2=0.2
HC(PPM) Max=49 AVE=7 MEAS=12
CO(%) Max=0.55 AVE=0.03 MEAS=0.01
NO(PPM) Max=774 AVE=50 MEAS=1434 FAIL

I changed plugs, wires and cap and rotor, did an injector cleaner (fuel additive type) Ran the car for 300 miles, and ran the car driving, and at idle for an hour before the test. I left it run the entire time while I was waiting for my test to make sure the cat was up to temperature.

I was looking, but I dont think my car has an EGR. Everything in the download-able manual seems to indicate the 1997 HX only had an EGR when equipped with the CVT. My civic is a manual.

The car runs fine, getting good mileage (33-35) all the time. The Smog test guy said everything I did would make the car run better, and increase performance, and there for INCREASE the Nox.

I am totally open to suggestion. Thanks.

 

http://www.tegger.com/hondafaq/egr-fix/index.html

 

Every California model HX should have the EGR system. Look for the big plastic valve (don't confuse it with the VTEC valve) and the plate on top of the intake manifold.

 

the diy link i posted shows everything step by step