Failed Smog 2 Times (Civic VX)
 

So I'm getting frustrated with my civic vx which is my backup car and car that I used for pizza delivery for 8 months while in college. Now that I want to sell it I can't pass smog, even though the last time it was smogged which was 1.5 years ago, it passed with flying colors. Now I'm getting ridiculous amounts of NOX that is driving me insane. I've done many repairs but can't seem to pinpoint what is causing me to fail. Below is a list of everything I've done.

Retarded Timing to 13 Degrees (125,500 Miles)
Recleaned EGR and EACV (125,000 Miles)
New Distributor Cap and Rotor (125,000 Miles)
New Thermostat (125,000 Miles)
Replaced Input Shaft Bearing and Axle Seals (125,000 Miles)
New Radiator (122,000 Miles)
New Clutch (118,000) Miles
Replaced Throwout Bearing (118,000 miles)
4 Wire 02 Sensor (Auto Parts Direct To You)
NGK Spark Plugs (NGK Website)
Fuel Filter (Honda OEM)
NGK Plug Wires (NGK Website)
Exhaust Manifold (Dorman 674-545)
Cat Converter (Dorman 674-545)
OEM Honda Timing Belt Change at 115,900 miles
Water Pump Replaced at 115,900 miles
Replaced Stock Muffler at 115,800 miles
Cleaned EGR Valve at 116,100 miles
Cleaned EGR Ports/Intake Manifold at 116,100 miles
Cleaned EACV at 116,100 miles

While I had my pizza delivery job I had converted the car to Fed with the new ECU, conversion harness, and 5 Wire O2 sensor. After it failed with the Fed conversion I decided to go back to CA ECU and new 4 wire O2 sensor. My results with the CA ECU and O2 turned out worse than the Fed. I have no idea what is wrong. I ran Guaranteed to Pass and Gumout Fuel Injector Cleaner already. I even ran it close to E before my last test and filled it with 1.5 quarts of Denatured Alcohol and still it did not pass. (And yes I've now diluted the alcohol with regular gas.)

The only current problem with the car is that it has an intermittent CEL with code 1 for oxygen sensor or sometimes code 0 for ECU, they are never both on at the same time. I tried switching over to my FED ECU to see if I get a CEL and I get code 41 for primary o2 sensor heater. I don't see why anything would be wrong since I've tried the old and new o2 sensor and still get the same codes. Also, I have an extremely low idle with the car, it will idle all warmed up at about 200 to 300 rpms, it has never died but I can't get it to idle higher without experiencing a fluctuating idle. Oh and the EGR was tested and works fine. Can anyone help out?

Here are my most recent results:
1st Test
https://www.fuelly.com/attachments/fo...0ea7c18ddb.jpg

2nd Test
https://www.fuelly.com/attachments/fo...ac412027e9.jpg

OK...you've cleaned the EGR. BUT...is the EGR opening at the appropriate time? I had a similar problem with my '83 Cad Eldo a couple years ago. What I discovered was that the EGR valve was never opening. There was apparently a blockage in the vacuum port which controlled the EGR valve. Therefore, the EGR was inoperative. In my case, there was another port next to it, off of which I was able to attach a tee. This provided the required vacuum to operate the EGR, and to allow me to pass when I got the car re-tested. Hope this helps...

Looks like you are too lean all the time - your HC Hydrocarbons are lower than they need to be and the lean condition will result in higher NO levels from the excessive air/fuel in the mixture.

You mention getting an 02 heater code. I know you said you replaced it and tried the old one but, I suspect that's where the problem is, but can't be sure. What has you fuel mileage been like lately? Any decrease in mileage? I've had 02 sensors cause as much as 25-35% drop in FE before.

Another thing to take a look at would be vacuum lines or a leaking intake gasket. It may be sucking raw air causing the low/rough idle and making it run lean. Back several years ago when I had my '88 Escort smog tested it maxed out the emissions testing equipment, the problem was a bad vacuum line going to the MAP sensor. There are a couple ways to check for vacuum leaks. You can spray starting fluid around the vacuum lines and intake gasket and it the idle increases you've found your vacuum leak or you can take a length of hose put one end at your ear and run the other end along the hoses and around the intake gasket and if there's a leak you'll be able to hear it sucking air though the hose. Personally I like using the hose, because I don't like spraying highly flammable liquids around a hot engine and exhaust. Just be careful and don't get the hose caught up in any moving parts.

You mentioned replacing the EGR valve too. Did you check the port in the intake where the EGR valve attaches to see if it was clean or not. I know Ford Escorts are really bad for that opening to get plugged up with oil and junk and completely stop the EGR flow. On them you can usually see that the opening is completely closed or near closed when you remove the EGR valve, but you still have to use a screwdriver or stiff piece of wire to reach back into the intake and remove all the junk. Sorry for the long post, but I was just trying to give you a few ideas and things to check.

Thank you for the replies, in response to FordMan I will investigate to see if there are any vacuum leaks, if not I'll remove and clean the intake manifold. As for my o2 sensor, the VX is getting at least 42mpg, if I were to drive according to the speed limit I know it'd be at least 45 mpg if not more. So that's what makes me think it's not the o2 sensor and maybe faulty ECU wiring. I'll go through the list and see what I can repair first starting with the vacuum leaks.

Ok, so I think I've found my problem and it lies in the ECU. I found two pins which were very similar in color and they were switched. This was for the primary o2 heater and LAF sensor. So I'm pretty sure things will be much better now. Also, I have some concerns regarding other pins, and if anyone can help me out I'd appreciate it. So I looked at the ECU pin diagram for the VX in both the downloadable manual (2nd to last page, pg. 1257) and also at an OBD1 pin diagram I found through google search. Both tell me what color the wire should be and the one I found online also tells me what it's used for. Here are my findings:

A11 is said to be Orange/Blue or Red but mine is Pink (EGR)
D3 has quite a bit of electrical tape (Knock Sensor)
D11 is said to be Light Green or Red/Black but mine is Pink (Throttle Position Sensor)
D17 is said to be White but mine is White/Pink (MAP Sensor)

I don't know if the color variations really matter at all but I'm just trying to get everything done and done right. Thanks!


Update: Passed smog with NOX below 50ppm! It was just the wires the whole time, oh well, now time to sell, thanks everyone!