Ok. Lots of great info here. I took a closer look and I have a 4-wire sensor. All of the wires are in perfect shape. Is there any way the sensor went bad or should I prepare to send the ECM back to Howell? I hate to put $60 into a new sensor. I have never seen one go bad that fast.
The 4 wires on the sensor should be white-white-grey-black. The two white wires are for the heater, the black is the sensor signal, and the grey is the sensor reference.
If you put 12V across the two white wires, the tip of the sensor should get hot.
Here is a link to a YouTube video showing how to check the sensor. Connect your volt meter across the black and grey wires.
I think that's what he means - the "off road" system doesn't come with a heated sensor, only the CA kit does AFAIK.
It's my understanding that the difference between the "California" and "off-road" versions, at least for the 4.2, are that the Ca kit adds a heated O2 sensor, a VSS, a CEL, and an emissions-friendly PROM in the ECU.
That said, the OP said his "Non-California" kit for his 304 came with a heated sensor, then confirmed this by verifying that his sensor has 4 wires.
I purchased the off road kit and was charged for adding the heated sensor due to my header. That is why it's good to order directly from them and they will tailor it to your needs. They add the heated sensor if you mention that you are running a header.
There has to be a stock application that's a replacement. It's garbage that Howell won't give the original application out so you can get replacement parts. What if you're stuck far from home and can't wait for them to ship you their $60 part?
I would dig around in the EFI forums at www.binderplanet.com and see if you can find a part number for the two wire, heated sensor.
I just had to replace my O2 sensor as well. I found that the stock application is a mid-late '90s Chevy 4.3L. I told the counter guy at Napa it was going in a '95 Blazer.
Ok, so I have a Howell TBI, headers, and a single wire o2 sensor. I'm experiencing the same problems as the OP. At first wasn't happening at all, now as it heats up. Is the suggestion here to go to a heated sensor? If so, how would I convert from a single wire to multiple? OBD code also throws a 44, which is "Oxygen sensor voltage was under 0.25 volts for 50 seconds of closed loop operation."