Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com - View Single Post - 92 Honda Civic VX Failed Smog High HC at 25pmh

California98Civic · 12-07-2017, 06:08 PM

I kinda understand the lean burn system in the Honda but not completely thoroughly. Still, I'm pretty sure HC is not the primary side effect of lean burn. NO would be the high level from lean burn it seems to me. So I'm not sure changing the ECU, oxygen sensor, and harness to convert the car would be such a good idea since the problem might be elsewhere. Also, when the technician plugs into your OBD port he's gonna be looking for the proper ECU in the car. He'll be identifying it electronically. I'm not certain, but you might fail just for having swapped out the ECU.

A thought that I have is that perhaps the CAT is really old. There is a process for cleaning the catalyst using a combination of citric and oxalic acid. It seems to work from what I have seen people do online with it. And the process was scientifically proven to work in a lab. I did it with my own catalyst but my procedure for the testing of its effectiveness got botched. So I can't personally vouch for whether it works or not. But I have no codes showing. The CAT on my civic is 18 years old. Try cleaning it?

12-07-2017, 06:08 PM	#7 (permalink)
California98Civic Cyborg ECU Join Date: Mar 2011 Location: Coastal Southern California Posts: 6,299 Black and Green - '98 Honda Civic DX Coupe Team Honda 90 day: 66.42 mpg (US) Black and Red - '00 Nashbar Custom built eBike 90 day: 3671.43 mpg (US) Thanks: 2,373 Thanked 2,172 Times in 1,469 Posts	I kinda understand the lean burn system in the Honda but not completely thoroughly. Still, I'm pretty sure HC is not the primary side effect of lean burn. NO would be the high level from lean burn it seems to me. So I'm not sure changing the ECU, oxygen sensor, and harness to convert the car would be such a good idea since the problem might be elsewhere. Also, when the technician plugs into your OBD port he's gonna be looking for the proper ECU in the car. He'll be identifying it electronically. I'm not certain, but you might fail just for having swapped out the ECU. A thought that I have is that perhaps the CAT is really old. There is a process for cleaning the catalyst using a combination of citric and oxalic acid. It seems to work from what I have seen people do online with it. And the process was scientifically proven to work in a lab. I did it with my own catalyst but my procedure for the testing of its effectiveness got botched. So I can't personally vouch for whether it works or not. But I have no codes showing. The CAT on my civic is 18 years old. Try cleaning it? __________________ See my car's mod & maintenance thread and my electric bicycle's thread for ongoing projects. I will rebuild Black and Green over decades as parts die, until it becomes a different car of roughly the same shape and color. My minimum fuel economy goal is 55 mpg while averaging posted speed limits. I generally top 60 mpg. See also my Honda manual transmission specs thread.