My '91 Civic just failed California smog test. First, some background. I purchased this car with a blown head gasket and a very tired D15B2 engine. I thought that I should replace the engine and found a D15B7 engine. I transfered the intake manifold from the D15B2 to the D15B7 engine as I did not want to start a new project converting one FI system to another for lack of time and finances. I have the DPFI manifold installed onto the replacement engine. The engine runs very strong and smooth. However, it did not pass smog. The following parts have been replaced: plugs, wires, cap and rotor; O2 sensor, PCV, timing belt and water pump, coolant and thermostat. Engine oil and filter as well as the air filter. Timing is set to 16* BTDC. The engine was at operating temperature prior to testing, and the gauge was reading one third of the way up from cold. The test figures are as follows:

15mph: RPM 1987; CO2 14.04; O2 0.83; HC max 91 - ave 33 - measured 80; CO% max 0.57 - ave 0.18 - measured 0.56; NO max 585 - ave 345 - measured 584 --- PASSED

25mph: RPM 1854; CO2 14.00; O2 0.82; HC max 73 - ave 27 - measured 92; CO% max 0.48 - ave 0.14 - measured 0.54; NO max 542 - ave 290 - measured 732 --- FAILED

Should I have transfered the head and valve train components from the old D15B2 engine to the D15B7? At present the D15B7 has its original head and valve train. Your comments and suggestions are greatly appreciated, especially, from the knowledgeable and experienced techs among you.

 

Since you have almost covered everything what is left? CAT. Your O2 reading is high, higher than what I would like to see. Also all of your numbers are high so that points to the cat too. Unless the O2 is from an exhaust leak.

Usually when you blow a head gasket you get coolant thru the exhaust and the coolant will contaminate the cat, thus reducing it's effectiveness.

That is what I see....

OO
\_/

 

Clean your EGR Valve ports (inside your manifold) and if possible test your egr to make sure it works- Your high in NOx. and also HC seems a bit high, check your o2 sensor(s)

 

Thanks, guys. I was leery, from onset, of the CAT being ruined by the failed head gasket and coolant contamination. As far as the EGR valve goes, I cleaned the valve and tested its operation, per the Haynes manual. I also cleaned out the EGR passages in the head and manifold, as far as I could reach with wire brushes and brake kleener. The O2 sensor is brand new. I will check for exhaust leaks. Unfortunately, for me, I have run out of time to make any repairs, and I must go face the DMV tomorrow to see about getting an extension... wish me luck! This has been a very harrowing experience, and a costly one.

I appreciate your comments, very much.

 

I failed my California smog test w/similar readings and had pretty much replaced everything also. In the end, I replaced the cat with a new magnaflow unit and it resolved the problem. What brand oxygen sensor did you use? The reason I ask is because my friend's car failed with similar readings and he had just replaced the oxygen sensor with some generic part the he had to cut and reuse his original electrical connector. After replacing the generic oxygen sensor with a NTK sensor, his car passed. Good luck.

 

If your NOx are high I used seafoam through my vaccum lines to clean it out before you smog It should reduce your emissions.( works like magic )

 

Thanks for the input, guys. Do you know which P/N Magnaflow CAT you installed? I have looked online and found few that are legal for sale in California (50 State legal). Also, when I transfered the D15B2 intake manifold (DPFI) over to the replacement engine, I cleaned all the intake runners thoroughly, as well as the EGR chanel, and the appearance/condition of the ports of the replacement engine were absolutely spotlessly clean. As for the O2 sensor, I used a Bosch, vehicle specific.

I am inclined to believe, the main contributor to correcting the high smog readings will be replacing the CAT and fixing the air leaks in the exhaust, if any. Now, I'm off to see what I can arrange with DMV, to buy some time to effectuate the needed repairs.
Thanks again!

 

Take your test report with you to show them that you are trying if the date on the report is within the last couple of days. They will be more likely to give you an extension.

The Magnaflow cat is a part of Carsound cat's. You should be looking for a CARB # D-193-84
It is a 37000 38000 series cat and is a generic cat for 95 and older passenger cars. If you want call them 1-949-858-5900 They should have more info for you on it.

 

I took the smog report with me to DMV, as you suggested, but was unable to get an operating extension from the DMV. I was reminded of the overly generous time they had so kindly alloted me, to complete smog certification. However, fees are paid up until Jan 2011, and I can work on my car as long as it is not on the streets. Then, I can go back and plead with them for a one-day permit to take the car in for smog test. This is very generous of them, isn't it? I could go on, sarcastically, about the California DMV and CARB, etc., but it would not solve anything, nor do I want to bore anyone with my issues. The bottom line is, I have some time to tinker with my car to get it running right. As soon as I can figure out which CAT to order; one that meets the unrealistic expectations of the enviro-**** goons, I'll be able to resume where I left off.

On my way back from the DMV I, foolishly, entertained the idea ... what if we ALL told them where to get off and no one complied with their tyranical demands about smog tests and the like? That notion alone, put a little 'git' in my step, which I needed desperately.

 

from your reading, your 02 is high which means your running lean, which running leans=high heat in your combustion chamber which in terms=high nox. try your cat to see if it helps.

 

This info is very much appreciated; I shall follow-up accordingly. Thanks!

 

Thanks thesmogman! You were absolutely correct in your assessment of my car's problem. The car passed smog today and I'm quite pleased. The main culprit turned out to be, as you so rightly pointed out, the CAT. I purchased the CAT online for substantially lower than I was quoted from the local shops in town. It needed to be 50 State legal so as to comply with the overbearing California laws. Of course, I had to remove the old one and weld some pieces together, but it was not difficult at all. I also replaced the gaskets and seals in order to prevent exhaust leaks. THe results were astounding, and the smog tech. commented that he had not had a car run this clean in several years.

Thanks again for your assistance.

Norman C

 

 

nevermind