Hi, I am new to this forum and I need some help.

Just purchased a 97 CRV with 215,000 miles from a friend (who was the original owner). It failed a CA smog test, but only because of high HC reading at idle. It is not throwing any codes. The engine runs well and it idles smoothly. See test results below:

RPM 739
%CO2 13.9
%O2 0.4
HC (max allowed) 100
HC (measured) 124 - failed too high
CO% (max allowed) 1.00
CO% (measured) 0.31

I read forum posts and one suggestion was to check the idle speed ignition timing. It was retarded by 6 to 8 degrees, so I followed the procedure in the Chilton's manual and advanced it to 16 degrees (14 to 18 allowed).
I then had it retested at the smog station:

RPM 740
%CO2 14.9
%O2 0.5
HC (max allowed) 100
HC (measured) 170 - failed too high
CO% (max allowed) 1.00
CO% (measured) 0.33

Some background:
The previous owner had new spark plugs, wires and distributor installed about 800 miles ago (mid-April '13). Engine would not start, he had it towed to a repair shop and they did the work.
I replaced downstream O2 sensor because the wires had been damaged (somehow) and it threw a code indicating a problem with that O2 sensor. When I took out the old sensor the portion in the exhaust stream had partially melted. I pulled the upstream O2 sensor after the first smog test to inspect it. It did not show any damage, so it has been reinstalled.

Any suggestions as to why it is running rich? Could it be a vacuum leak, thus throwing off the ECU which is then enriching the fuel mixture? A friend suggested that I adjust the valves to see if that would help, and because of the mileage it is probably overdue.

I have searched other sites as well, but those postings include other symptoms (such as high NOx or rough idle) for those engines which are not present with this engine.

Thank you in advance.

 

Normally HC would be tune up stuff. Plugs, 02 sensor, EGR valve (if it has it)

 

No EGR valve on this engine.
New plugs, wires and distributor less than 1000 miles ago.
New downstream O2 sensor, but my understanding is that its main purpose is to determine catalytic converter efficiency.

The upstream O2 sensor output is used by the ECU to determine if the air/fuel mixture needs to be enriched or leaned out. At, least that is my understanding.
So, replacing the upstream O2 sensor might make sense. But, it is not throwing a code and just throwing money at replacement parts in hopes of fixing the problem is what I am trying to avoid.

 

Any suggestions as to what might be the cause?

Still only one reply to my question.

 

Hi MNFinn Im having the same problem did you ever find a solution?

 

Hello,

You may have a bad sensor but I guessing that the CAT needs cleaning out. There is a product on the market called "Cat-a Clean" and it's just a simple case of adding it to the fuel tank and run the car normally.

Worth a try.

Regards,

Kev

 

Check the PCV valve.

Also if you noticed, when you set your timing to proper point HC level went up...if you want set distributor to full retard and test again to see it if will pass.

 

This vehicle does not have a PCV.

I have heard about the trick of retarding the ignition to try and get it to pass a smog test, but I suspect that retarding the ignition will only work if it only fails by a small amount. I could be wrong, but the timing cannot be adjusted very much. The amount of available rotation on the distributor is rather small.

 

Hello,

Yes your CRV does have a PCV fitted ==== Item 2 in the link below.

Honda Car Parts / Choose by Model / Genuine Honda Parts | Honda Cars | Honda Motorcycles | Honda Power Products | Lings Honda

Kev

 

UK-Kev,

You are correct, it does have a PCV. I had replaced it already.
I meant to say that it does not have an EGR valve.

Brain fart on my part.