I have a 91 Si that I recently purchased. The guy I bought it from gave me a passed emissions form from late last year. The motor had a lot of miles on it, so I swapped the engine from my 90 CRX Si into it. My CRX also passed emissions less than 6 months ago.

I took my Si in today and it failed emissions, all three areas. (HC, CO, and NOx)

This was puzzling to me because while the engine isnt the same, both the car and the engine passed. (Though they werent together at the time)

When I did the swap, is it possible that I may have neglected to hook something up properly that affects the emissions? The car runs perfect and gets 30 mpg.

If it isnt possible I screwed something up, why did it fail? What can I do to fix it?

Thanks

 

need more info...how bad did it fail in each of the categories?
who did your swap? are all emission controls hooked up?

 

Nice screen name

 

I did the swap, and am pretty experienced at it.

My readings are: Allowable
HC-ppm 151 136
CO-% 1.36 .76
NOx ppm 1545 984

That is all at the 25mph test. The 50 is pretty close to the same ratios.

I assume all emissions controls are hooked up, but that is part of my question. Is there a control that would cause it to fail in all three areas?

 

ur cat would be a must be if u failed emissiond in all 3. thans what im thnking.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by charlee &raquo;</TD></TR><TR><TD CLASS="quote">ur cat would be a must be if u failed emissiond in all 3. thans what im thnking.</TD></TR></TABLE>

Thats what I thought, but the cat worked fine less than a year ago. Could it have gone bad that quickly?

 

Three strikes your out, Just kidding.

All three points me to O2 sensor or cat. What is your O2 reading from the test?

How old is the gas in the tank? Have you added any cleaners to the gas?

Usually with a bad cat your Nox numbers would be alot higher, but with all the HC it is hard to tell.

 

Bringing this back. I replaced my cat, o2 sensor, and changed the oil. I took it back today and passed all of the 25mph tests, but the 15 mph test I failed on
CO-%, and I actually got higher than I did before I replaced everything. My CO-% at 15 mph is 1.46 with an allowable .79.

Any ideas? Everything else passed!?!?!?!

 

Check if your MAP sensor is hooked up, vacuum lines and wiring.

 

I have no CELs, wouldnt a MAP sensor issue throw a code?

 

If your vacuum line is disconnected from the Map, your CO will be very high. On the OBD0 vehicles I don't think it will catch it(CEL), unless you have the sensor disconnected.

 

The strange thing is that I passed CO at 25 MPH, but failed it at 15 MPH.

 

Did you warm the car up good? You know the cat has to be broken in once you get it, right.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Mr.Smog &raquo;</TD></TR><TR><TD CLASS="quote">Did you warm the car up good? You know the cat has to be broken in once you get it, right. </TD></TR></TABLE>

I didnt know that. The cat has been on for about 300 miles, and I drove the car 50 miles this morning on the way to the testing center.

Is that not enough?

 

That's more than enough. When a car fails smog at my station then gets the cat replaced, I tell the customer to drive about 5-10 miles. It normanlly works well after that, sorry man I don't kknow what else to say. Even though you replaced the O2, I would double check the connections cause it sounds like you may have a lazy 02. Do you have a chipped ecu? Some of those programs make the fuel curve aggresive. I have a chipped PW0 with my B16a swap in my CRX, CO is around 4-4.5%. I figured I need another ecu cause my mpg is very low and don't wanna pay at the pump. Good luck with your diagnosis, wish I could hepl more.

 

advance the timing. CO is created when not enough heat is there for the amounts of fuel to completely burn it off.

 

bump, any more help?