Kguy

Good morning everyone. I'll keep this short and to the point.

For the past few months I have been having problems with my Civic failing smog. In January 2014 I took it in to get it smogged for tags and it failed miserably.

Back in August of 2012, it passed with very low numbers all around after I had replaced the o2 sensor, cat converter, decarbonized the engine, and put the timing back into spec (16 BTDC).

Continued in next post*

Kguy

My apologies for the double post, I hit the tab key and it posted prematurely.

Please read the first post before reading this one!

Now it is failing and no major work has been done to the engine since it passed back in August 2012. After failing the test in January 2014, I was informed that the Cat was no good and was instructed to replace it. After replacing with the same one that was on before (Magnaflow), I had the car tested again and still failed with a gross polluter, just not as much as before.

Determined to get this issue resolved, I have been taking my car to my smog tech who has been in the business for a long time and owns his own test/repair facility and they have ruled out the following:

1. Timing still in spec. (They thought the harmonic balancer had slipped)
2. O2 sensor still functioning (air/fuel mixture spot on)
3. No EGR (these engines never came with one)
4. Speculated the head has been milled, and compression is too high (has never been milled)

I am wondering if you guys have any ideas to what is going on, I would really like to get this figured out. My tech seems to think there is what he called a "hot spot" somewhere in the engine and will be difficult to track down.

As for CEL's, I do get one for the O2 sensor (1 short blink) which comes on intermittently and has ever since the first day I have had the car, even after replacing the sensor. The CEL even would come on around the time the car passed. Another CEL that has been popping up is the crank sensor (4 short blinks), and have mentioned it to my tech and he said there really isn't one one this car unless it is throwing it for something in the distributor (I forgot what he called it)

My Car:

1995 Civic EG Manual
1.6L D16Z6 with approx 140,000miles (maybe more)
DC 4-1 headers (carb approved)
Spectre intake (carb approved)
Magnaflow CA approved Catalytic Converter. #336304 Carb E.O. #D-193-109

(only listed mods that pertain to smog components)

Here are the tests:


This is the test when it passed back in August 2012. Using the same cat and everything else. Very low numbers.




January 2014 Test BEFORE cat was replaced (initial test in order to get tags) (this is the same cat used when the car passed beautifully)




Here is the test AFTER I replaced the Catalytic converter (March 2014)

This may be irrelevant, all 3 tests were conducted at the same facility. A Gold Star certified CA Test only smog center.

Kguy

Does anyone know what the issue could be?

JUICE66

The cat should have came with instructions that tell you that you must replace the o2 sensor with a new one when replacing the cat...

The o2 sensor might be wired incorrectly. The colors on the replacement ones from bosch do not correspond to the same color in the cars wiring...

Don't ask me how I know that.

Former User

The lamda values for your most recent emission test (15 & 25 mph) are acceptable.
http://www.smogsite.com/calculators.html#lambda

Code 4 - problem in CKP sensor circuit. This CRITICAL sensor is located inside the distributor and, contrary to what your mechanic said, your engine does have a CKP sensor. Ohm test the sensor and it's wires. If those are fine, swap in a known good ECU.

Code 1 - can be thrown by a fuel system problem - measure the fuel pressure, test the FPR, and check for clogged fuel injectors.

Fix both codes before you return to the smog station.

Kguy

How do you know that?!

Just kidding.

Juice, thank you for your reply I appreciate your input.

I have been informed that the oxygen sensor, according to the tests is functioning properly. The oxygen sensor was replaced around the time of the first smog test (Aug 12).

Ron, I was hoping you would post on my thread, thank you so much.

Regarding the CKP sensor, could it be defective? I ask this because I just replaced the entire distributor with a new (not re-manufactured) less than a year ago (I would say 9 months).

As for testing the sensor and FPR, I will get to it this weekend and get back to you on the results.

Former User

The CKP sensor has 2 wires, both of which run to the ECU. Code 4 could be caused by a bad CKP wire or a bad ECU.

Kguy

Okay so here is an update on my situation. It has taken a while because I am currently a full time student.

I replaced the distributor (was under warranty) and the car is still failing and giving me the same check engine codes. Car runs a little better, but still failing smog.

The other day I spoke with my tech about how I did a continuity test on the O2 sensor back when my car was first failing smog (in August 2012), and how there is a break from the plug of the o2 sensor to the ECU (I believe it was the ground wire).

Ron, it seems like this is the problem because I am still getting the 1 and 4 codes after replacing the distributor. My tech said that I may have a bad ECU as well because what I posted above regarding the break on the o2 wire. Should we do any tests before I purchase a used ECU?

Former User

Test the two CKP wires for a short or open from the ECU connector. If the wires test fine, then swap in a known good ECU.

Kguy

Today we tested the CKP wires and they were good. However we did a resistance test on the oxygen sensor wire to the ECU and found some major issues in my wiring. The oxygen sensor read a resistance of 3 ohms on the white with black stripe wire, and I believe he said that he got the same reading probing the terminals for the MAP sensor on the ECU plug as well.

My technician friend said that because of the complexity of the issue that in order to fix this problem I am more than likely am going to have to replace the wiring harness.

I was really hoping it was the ECU.

Outrun

Any updates? My 1994 Civic EX with 406k miles failed smog, then when I changed the header to one with a CARB EO and also used Lucas fuel system cleaner the car tested again with worse results (Gross Polluter).