Per the Helm's shop manual for a Code 44, "The sensor is like an open circuit and produces no voltage when it is below about 360C (600F). An open sensor circuit or cold sensor causes "open loop" operation." The ECM supplies .45 volts to the O2 between terminal 9 and 14, the ground. By the way terminal 14 is were you would run the 4th wire from a 4 wire O2. The O2 varies the voltage within a range of 1.0 (rich) and .10 volts being lean. Actually it's more in the range of .350 to .800 if I remember, been to long.

The ECM set a Code 44 when the O2 remains below .2 volts for 60 seconds or more. Again, this info from the 1987 Helm's. With the O2 installed in the stock cast iron manifold I doubt the O2 will ever get cold. But installing it down stream in a header collector it should run cooler.

I've installed a couple wide band A/F meters, they all have heaters so once they are up to temp they don't "drop out", but they will need to warm back up even after being turn off for a few minutes on a hot start. Just the nature of an O2 needing to be a certain temp to work.

Years ago I verified this when I ran CCC, headers and had a real time scanner while driving. Sometimes, not all the time but if conditions were right idle would go into open loop.

The old Alltest 3258 Brainmaster was pretty good for reading the CCC system, it's still in a case under a bench at the shop. There are several on Ebay now, a handy tool if you need to run CCC.

Dylan, not trying to step on toes. Years ago another gentleman here did a workup on the CCC programing, I printed it out, like 10 pages of 11x17 paper,I didn't understand the "logic" then, still don't. But do appreciate the effort you put into the CCC. Somewhere in the programming the ECM monitor voltage at terminal 9, (the O2's .45 vdc supply) and is a go, no go for loop status.

There are probably four 079 ECMs laying at the shop along with PROMs for an LG4, SS, ZZ4 EGR delete, and a Caprice 350, collected that stuff many moons ago when I needed CCC to be legal. One of these days I'd like to throw the CCC carb and dist back on the 427 and take it back to the track. Just not sure if a PROM could be burned with a timing curve suitable for my setup. I would guess it's possible to "adjust" the Vac, Temp, TPS, O2 parameters and then take a look at the M/C input from the ECM and tweak the fuel curve a little.

Off topic here, but one thing I did years ago was play with primary metering rods in the CCC. Most all CCC SS Q-jet carbs used the same rod, .026/.056", 75 "large window" jet. A donor DualJet carb yielded a set of .025/.053 rods, and another donor a set of 76 small window jets, which I made large windows. Even bought the primary metering kit from Chevy they sold for the ZZ4 upgrade into the 3rd Gen F, #17087129, it has .026/.056 rods and 75 large window jets, the same parts the SS came with, a waste of money. The donor slightly richer .025 tip along with the 76 jet helped the WOT a tad, and the richer part throttle .053" section helped the transition into the power circuit, until the EGM used the M/C solenoid to catch up to what just happened. The ECM's problem is it's always looking for that 14.8 A/F, except at WOT. That's why you can only fool that slow ECM for a split second with the different rods, but I thought it was something you could feel, the car ran better.
Sorry, got off track.

Last edited by mmc427ss; 02/03/16 05:04 AM.