Fuel mixture needs adjusting in 1999 CR-V


tshih
05-13-2009, 02:40 PM
My 1999 CR-V with 175000 miles started to show the CEL and code reader says catalytic efficiency low one bank. I can smell fuel and tailpipe is rich with soot. Question: besides changing to another new cat (done 30,000 miles ago) and doing a tune up of changing the sparkplugs, distributor cap/rotor, what else can be adjusted? I believe the 10%ethanol gasoline sold today is a cause of the CEL and mixture need to be adjusted. How and where do I start.:banghead:

somick
05-13-2009, 04:19 PM
Spark plugs, distributor cap, etc are important but I would start with O2 sensor.

Good luck,

Sam

tshih
05-13-2009, 09:39 PM
Sam,

It is a great suggestion which I considered as well. One would think that the OBD2 system would have thrown a code for bad O2 sensor if that was the problem. I'd assume that the values of the readout for the post catalytic sensor is not what's expected from the pre-cat O2 sensor. Because ethanol is present in excess and that leans out the mixture being burned in the engine, the cat is working but the values are not what it's preprogrammed mapping expects.

I have a broad band O2 sensor in the form of a LM-1 from Innovate Motorsports which allows me to measure the exhaust for air-fuel ratios. I suppose I can take readings before and after I do a tuneup and after I change the O2 sensors.

somick
05-15-2009, 03:19 PM
Bank one efficiency usually points to a O2 sensor. What exact code did you get.

Tegger has lots of information about aftermarket exhaust. See if you can find something for you there:

www.tegger.com

Good luck,

Sam

tshih
05-16-2009, 12:30 PM
Sam,

Since the car has 176000 miles Ithink I'm going to take your suggestion and change the O2 sensor first. Will post results after.

tshih
05-20-2009, 09:56 AM
Sam,
the problem appears to be a blown gasket between the headers and the catalytic converter. The car was sounding like a ricer with the big tin can muffler and I could smell exhaust fumes. This weekend should solve the code and replace O2 sensor and gaskets.

Best regards,
Tom

somick
05-20-2009, 11:38 AM
Sam,
the problem appears to be a blown gasket between the headers and the catalytic converter. The car was sounding like a ricer with the big tin can muffler and I could smell exhaust fumes. This weekend should solve the code and replace O2 sensor and gaskets.

Best regards,
Tom
Thanks for posting! I hope everything will go well. 176000 is not a mileage when you dump Honda!

Good luck,

Sam

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