Car is modified - see signature. The original 82 exhaust system placed the O2 sensor right after the point where the passenger side exhaust dumps into the pipe and just before the system turns toward the rear of the car. The car had Hedman shortys with a hack job stock style "t"-pipe and the O2 sensor was in the stock location. I recently put on a set of Hooker shortys that moved the O2 sensor up to the collector on the driver's side. I extended the factory wire and installed a brand new Delco O2 sensor in that location. At the same time, I installed a Hooker y-pipe and a Zeitronix WB O2 setup. I put the WB O2 sensor about a foot in front of the cat con, which is is a little further rearward than stock. Also, now that I have the WB, I changed the BIN to force open loop. I was doing tuning runs with the EBL Flash on the Hedman header setup and the O2 sensor would output a relatively flat line on the EBL "DIAG" screen between 400 and 500 mv as the engine was warming up at idle. Once the car warms up, the NB line sits arount 875 mv at idle. At operating temp, driving at a steady cruise speed, the sensor would output a sine wave that would oscillate between 100 and 800mv. With the Hooker setup, the shape of the NB output and the range is the same as the car idles warming up. Once the car warms up, the NB line sits around 875 mv. The WB reads around 13.0 The shape of the WB line generally follow the NB line. Now, when I drive at a steady cruise speed, the NB reads either 900 or 50mv. The WB line is relatively stable in the 13-16 range, depending on speed. Both lines will move with throttle transitions. What's causing my confusion is how the NB is acting differently at steady cruise between the two setups. I don't know which is normal and want to make sure the system is currently operating correctly.

The difference in the NB O2 signal is the difference between running closed vs open loop. In closed loop the ECM forces the NB signal to oscillate. If the NB reports rich the injector PW is reduced to force it lean. When it reports lean the injector PW is increased to force it rich. This is why the NB reports as a oscillating signal.

In open loop this ECM functionality is turned off. The injector PW is what it is. Although a stored BLM value will still be used. So be sure that the key-on (init) BLM min/max is set to 128.

Note that by running forced open loop the ECM may toss an O2 malfucntion code (13, 44, 45). If it does no big deal other then getting a SES light. It won't affect anything while in open loop.

RBob.

Thanks! I wondered if it was related to being in open vs closed loop.

So is it the prop gains tables that control the amplitude and frequency of the O2 sensor waves when in closed loop?

Also, since installing the Zeitronix WB and making the required changes to the BIN for open loop running, my engine will cut out every one in a while. When I drive the car for an hour, it might do it 4 or 5 times. If I am at a stop, the engine will usually die. If I am driving, its like I turned the engine off and then back on real fast. The faster I am driving, the less I feel the effects of the cut out.

I was cruising down the highway this evening with the DIAG screen up when it happened (no data log). AFR was in the 14-15 range, I felt the engine cut out (like maybe 1/10 of a second) and the AFR spiked to 20 and then went back to the 14-15 range after the engine kicked back in. I continued on down the highway.

I had to disturb the ECM and knock sensor when I installed the Zeitronix controller. I used Velcro and a zip tie to mout it to the ECM. It doesn't seem like a loose wire thing and the ECM is not throwing any codes. Could it be a setting in the BIN causing an issue or could the Zeitronix be creating some electronic interference?