I did some searching and there were many posts on O2 sensors, but I didnt' see one that answered my questions.

So my OBDII B18C5 (51k) Hatchcrap failed emissions. Last year I was able to go the redneck route and put in a bottle of "Must Pass" and passed emissions. This year I wasn't so lucky. The guy at the testing center looked at my results and said it was most likely a bad Oxygen sensor (I did all the usual stuff -- changed plugs, wires, oil&filter, tested it with engine hot, etc). It's my track car, but I still want it legal to drive on the street, since I don't have a truck & trailer.

So anyway, I went to Pep Boys and bought a universal O2 sensor for $59. I'm cool with the wiring instructions, but which sensor should I replace? The one in front of or behind the Cat?

BTW, here are my emissions results:

25/25 Test
HC ppm 380 (136 to pass) FAILED
CO% 10.99 (.76 to pass) FAILED
NOx ppm 0 (984 to pass) PASSED

50/15 Test
HC ppm 214 (141 to pass) FAILED
CO % 1.05 (.79 to pass) FAILED
NOx ppm 412 (1088 to pass) PASSED

Also, Pep Boys has the ~$60 universal O2 sensor and a ~$300 O2 sensor. What is the difference between the two?

Thanks for the help guys. I have the new O2 sensor in hand, and want to make sure I pull out and cut up the right O2 sensor.




Modified by SpiceyRice at 4:36 PM 7/3/2004

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SpiceyRice &raquo;</TD></TR><TR><TD CLASS="quote"> The guy at the testing center looked at my results and said it was most likely a bad Oxygen sensor</TD></TR></TABLE>
LOL, that's probably what he say to everyone that doesn't pass. If it is the o2 it would be the primary. I would make sure it was bad before replacing it, don't like throwing parts at them.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Chiovnidca &raquo;</TD></TR><TR><TD CLASS="quote">If it is the o2 it would be the primary. I would make sure it was bad before replacing it, don't like throwing parts at them.</TD></TR></TABLE>

Welp, I took a look under the kaa, and the front O2 sensor looks like the one I just purchased. The rear one looks skinnier/different. I went ahead and pulled the front O2 sensor -- it's all black with soot (Im not sure what a good one, normal old one, looks like).

The universal Bosch O2 sensor I purchased is 'universal' because it doesn't have a Honda specific plug -- just 4 wires. You have to cut off the plug that your existing O2 sensor is using and splice it on to the universal O2 sensor. All done, that was pretty easy.

After sticking the new O2 sensor in (with a little anti-seize on the threads) I started her up -- cool, no CEL light! I decided I'd take her on a little drive around to see how she's feeling. Initally she seemed a little quicker to respond on the throttle, and the initial startup RPMs came down to 1500 rpm (cold) much quicker than it used to. Once warm she was idleing at a happy 800rpms. A quick on-off on the highway shows she pulls nice and hard again at the top of fourth and a responds quickly when I downshift from fifth.

Overall I'm very happy. I think she's been running rich for sometime, and been a little sluggish. This little $60 O2 sensor netted me 10hp I'd bet.

I'll take her to see if she'll pass emissions on Monday. Wish me luck!


Modified by SpiceyRice at 6:59 PM 7/3/2004

 

keep us updated

 

Woohoo! I passed my emissions test the second time around! ...and she's running like new again.. CLEAN and strong! I think the problem was with my Primary O2 sensor.

25/25 Test
HC ppm 28 (136 to pass) PASSED
CO% .18 (.76 to pass) PASSED
NOx ppm 73 (984 to pass) PASSED
CO+CO2 % 15.2 (6.0 to Pass) PASSED

50/15 Test
HC ppm 23 (141 to pass) PASSED
CO % .20 (.79 to pass) PASSED
NOx ppm 70 (1088 to pass) PASSED
CO+CO2 % 14.9 (6.0 to Pass) PASSED

I went ahead and replaced my distributor cap and rotor while I was at it, and put in new oil [M1 5/30] (new oil each track weekend, so I prolly only had 500 miles on the old oil).

It's a little irratating that the bad O2 sensor didn't trigger a CEL, since I've been running rich for some time, and my CAT is probably all gunky now. Oh well. I'm planning on replacing my O2 sensor every 15-20k from here on out -- since I'm sure I'll start to see hp losses in that time (pretty much all track miles). I have to be honest though, I knew she was running sh!tty, just didn't want to deal with fixing the problem -- the emissions test forced the issue.

Anyway, morale of this story is if you failed emissions do the standard tune up stuff:
O2 sensor [$60 Bosch from PepBoys/Autozone]
oil/filter [~$30]
distributor cap [~$20]
distributor rotor [~$20]
spark plugs [~$20]
spark plug wires [~$30]
and
valve adjustment (which I haven't done, but it's on the to do list.)

Thanks for the support guys, I hope this helps someone else out in the future.