Guys-

My ole 1994 Honda Accord EX with AT failed emissions test today.

Everything looks just fine and within the limit, except CO% at 15MPH, please see attached report and advise how can I improve or have the car pass emissions test.

Oil and filter was changed less 1000 miles ago. Air filter, spark plugs/wires were replaced for last emission test(2 years ago). For rack and pinion replacement, middle pipe with O2 sensor was pulled and when it was tightened up, think it produced a miner exhaust leak in that area. Can that be the reason for failure at 15MPH, since at 25MPH pressure is more and less exhaust gases are leaking?

Please see attached emissions report and thanks for any of your input and help.

P.S: There is no CEL, car does not miss or have any other noticeable problem.

 

Can you type out the readings, because I can't see anything on the attached pic.

 

CO at 15 MPH is 1.87 with the limit being .5....at 25MPH the CO was .33 with a limit of .73.....

Anyway, if the plugs are two years old...the regular NGK's are only rated for 24K miles

Next if you "think" there is an exhaust leak,.....confirm and fix if so.

 

PAHonda, can you please try looking at the attached pict?

PM, can I try using steel band aid around the pipe area or proper gasket should be needed?

I am going to replace spark plugs and air filter. Is there a way I can actually see if there are any emissions improvements after the change?

Thanks

 

In 2013, car passed emissions without any trouble, at that time I did replace Spark plugs and Air filter. Since then Rack and Pinion and Headgasket has been replaced. For both, exhaust( or parts of exhaust system) has been opened. Does it mean exhaust leak is the main culprit or something else?

Please see attached report for 2013 results.

 

See following link.


BAT Auto Technical-Professional mechanics giving advice-An Educational Site w/ OBD2 Trouble Codes and Technical info & Tool Store.


Excess CO is likely due to excess fuel delivery; incorrect fuel pressure, leaking injector, slow O2 sensor. Diagnostics necessary to determine which fault is indicated. Difficult in a obd1 vehicle. If O2 sensor is old, then a replacement may fix the problem and is relatively inexpensive.


good luck

 

Thanks, can an exhaust leak cause CO related problems too?

 

Unlikely IMO.


good luck

 

If the exhaust leak is blowing onto the outside of the O2 sensor, then it can throw off the measurement. The O2 sensor actually measures the oxygen DIFFERENCE inside vs. outside the exhaust pipe.

 

So I have the car up on jack stands and observed it yesterday, one of the gasket before the CAT(31378) isn't seated properly, as it that part was opened for Rack and Pinion replacement.

I have highlighted in the picture, going to seat it or replace the gasket.

Also, one of the spark plug well has oil in it, seal is leaking, can it cause emission related problems or no?