Anyone fooling around with thier cars may have had the bad experience of failing the dreaded emission test. Here is PA they use the enhanced test where the car is dynoed and tailpipe emissions are read and reported to the state. CO% x liters, HC ppm x liters and NO ppm x liters are read. I did some engine work to my 89 and last go around it went through fine. This time I failed and amazingly enough nothing was changed. A new O2 sensor did not help. The ONLY change made was a high flow exhaust system. Rather than changing it I tried a heated O2 sensor. It flew right through the test. My conclusion was that the exhaust was too cool to keep the sensor at it's ideal range. My own pipe sniffer indicated it was in fact rich. Why no O2 code? After investigating the subject I found that the O2 sensor has to basically way out of range for a prolonged period of time before it will set an SES code. Second case was my 91 Lumina Z-34. Always was on the low side for emissions. Stock mufflers went and I put Flowmasters on. I failed, CO limit 1.10, went to 2.07. HC limit 275, went to 632. NO was fine. A new O2 did NOT again solve the problem. A heated sensor solved the problem again. Those of you out there might want to consider it. I used a 4 wire unit form my 98 Blazer. Sensor return and heater ground tie together to a good ground. I ran the heater power to the fuel pump relay output and the signal wire to the old location using the old connector. I got a Delco PT-368 plug to interface to the new sensor. The beauty is that I can unplug the heated unit and go back to the old style if needed. And the other benefit was I went to avg of 13 MPG to an average of 17 around town. Hope someone finds this useful.

 

Are these applications with stock manifolds?? If so, I think I might be upgrading to the heated O2 (only reason I haven't thus far is that I thought I was gonna be okay since I'm still running the L98 exh. manifolds at this point).. Granted, I don't have to worry about emissions, but if the sensor isn't doing its job correctly, my tuning efforts may be harder than they need to be.

 

This is why everyone always recommends a nice drive to get everything nice and hot before going in for the tests. :shrug:

 

I have a non-heated O2 with headers and in the winter it seems like it never gets warm enough. The O2 is real sluggish and the computer has to go alot each way to get what it wants to see out of it. Just driving around when its cold the sensor never seems to heat up all the way. I guess thats to be expected since the sensor has to be something like over 600 deg F for it to work properly. Maybe one of these days ill stop procrastinating and change over to a heated O2.

 

I want to switch over to heated O2 sensor when I do my headers but I'm having a hard time finding it on NAPAs website, how much do they typically run, and where can I find one?

 

Actually I did omit something, on the Camaro I did also put the Edelbrock TPI manifold and runner kit. High flow cat and exhaust and stock exhaust manifold. Bosch makes a universal heated sensor for most applications, they can be found on the net for anywhere from $45 to $90 typically. Reason I used the 4 wire was when my Blazer hit 50k I replaced all 4, yep 2 on the manifold and one pre-cat and one post-cat. I saved the old ones and when I had problems with the IROC that prompted me to experiment. I hardwired one in for testing and was amazed at the difference. I got a new one and the mating plug from Delco and dressed it up so it basically looks like the factory. I think the AC Delco was an AFS 105 sensor. They are pricey even with my dealer account, I would use the Bosch. The stock sensor has one wire for signal to the ECM and they use the threads into the manifold for signal ground. The Blazer feeds sensor ground through a wire to ECM ground hence the 4th wire. The Bosch is probably easier to hook up. It comes with instructions and connectors. The heater section draws 2 amps when cold then settles down to about 1 amp so voltage source is not critical. Just make sure its a key controlled source, you don't want it running all the time. I used the Bosch 3 wire on the Lumina. Anybody making changes should really invest in one, made a hell of a difference for me.

 

Its on my "in two weeks" list now..

Thanks for the testing and report!