Using the info from another post, "How to fix some of those common idle issues" I decided to see if it would help. I changed the idle O2 settings on my S_AUJP.V3.bin with TP4.0 and my 383 HSR combo. For header temp I used a Sears laser thermometer on HDR primary #3, same spot each time after approx. 5min of idling. Here's the results.

Test #1.
Stock settings resulted in:
Idle RPM = 900-950, BLM = 160, HDR Temp = 295F

Test #2
Changed Idle O2 R/L Slow Zero Error Lower, from 0.56 to 0.50
Changed Idle O2 R/L Slow Zero Error Upper, from 0.60 to 0.54
Changed Idle O2 R/L Threshold Fast, from 0.60 to 0.54

Resulted in:
Idle RPM = 900-950, BLM = 132, HDR Temp = 300

Test #3
Changed Idle O2 R/L Slow Zero Error Lower, from 0.50 to 0.46
Changed Idle O2 R/L Slow Zero Error Upper, from 0.54 to 0.50
Changed Idle O2 R/L Threshold Fast, from 0.54 to 0.50

Idle RPM = 900-950, BLM = 116 - 134, HDR Temp = 320

I left it with test #3 and pulled the #1/3 plugs. They have lightened up some but they're not a light tan yet. Could be due to previous use. Drivability seems unaffected. The exh/gas smell is still present but no longer makes my eyes water! Now the questions...

#1. Test #3 shows the BLM's ranging from 116-134, slowly going up to 134, then back down to 118, repeating as I watch for 3-5 mins. Have I reached the limit of the NBO2 sensor or should I try test #4?

#2. Can I cause any damage by going too lean in a "no load" (idle) state?

I know the NBO2 isn't perfect, but it's a means to measure from for now and I'm trying to avoid locking it to OL (Open Loop) since I do not have a WBO2 yet.

Cam is 230/236 dur, .544/.555 lift, 112 lobe seperation
Any tips or pointers appreciated. Thanks in advance.

 

It sounds like you need to try a new o2 sensor if you're having BLM's swing that bad and your eyes were watering... that's rich! Also, what do the spark plugs look like. They'll tell you how the combustion is going and if it's rich/lean/hot/cold.
Another thing that causes poor closed loop is fouled or cold spark plugs that misfire at idle from poor mixture "mix." That'll through the o2 sensor all off. A misfire, even slight, can cause fresh oxygen to get to the sensor causing the high BLM and the apparent rich condition. With that cam, you would want to play with the o2 PID routine but first get the mechanics running top notch. Also adjust the VE and force open loop until you get a clean idle (spark plugs need cleaning between tests) to eliminate the calibration being the route problem. From the sounds of it sounds like a misfire. I've had the problem and new clean proper heat range plugs did the trick with my old stock HEI ignition.

 

A little clarification...
I do have a brand new sensor from GM partsdirect, virtually everything is new and mechanics are sound with no misfires. BLM's are 126-130 consistently with the exception of idle. Previously, before I made any adjustments to the idle O2 settings, the exh was really rich at idle but reporting a 160BLM.

Since I changed the idle O2 settings, it has significantly improved but, now I have a fluctuating BLM.

You've already laid out the answer for me... lock it to OL and adjust the VE table by checking coloration of the spark plug. The only problem is, I know when I turn CL back on it will read lean again and the ECM will dump more fuel. Too bad I can't have OL at idle, say below 15 mph only then switch to CL for everything else. I know, I know, I want my cake and eat it too!

The changes I just made were drastic improvements to the exh fumes/smell. Kudos to you guys posting all the info!

EDIT: Just re-read your post, what is the PID routine??

 

One should also not forget that with a Distributor, your fighting what might be termed as a no win battle. The air gap crossing in the cap rotor is just a complete waste of spark energy.

A lean idle will result in the same engine damage, as going lean at WOT, it just takes longer.

Might read the thread on SEFI, and how much of a difference there is, just based on injector timing. Then armed with that realise that the batch firing is after the DRP, so there's only a limited chance of one injector out of 8 even being near optimum.

SEFI, when done right really makes a difference, and with the availibilty of 2240, it would seem to be a natural to use it and adapt a caddie distributor and just got for the best possible, IMO.

 

Not arguing that the gap crossing is bad but GM did something right with their opti design; Green is Opti, Red is a stock style HEI rotor.

As far as SEFI, I don't think anybody has any grounds to argue it a bad thing other than it's added complexity. Things like firing angles, the extra wiring involved, the more complicated crank/cam position sensors.
Is the 2240 well hacked? I haven't heard of it being used on an f/g/b body so it would be too much work for me. Maybe when I retire

 

Try this
http://www.diy-efi.org/gmecm/papers/747fuel.txt

 

I made some more slight adjustments to the Idle O2 settings, narrowing the gap seemed to help calm the BLM's. I figure it was that or it just took some time to settle with the new adjustments? It finally locked on to 122 for 90% of the time and the plugs shifted a few shades lighter so I adjusted VE's from there. Engine seems to be happy and exh is much improved.


Z69 - Thanks for the link I hadn't seen that before!

 

I guess you've never measured the air gap in the opti-nosparks.

 

Do you care to place a wager on that guess?

 

I'll wager the sequential injection and anything to do with the opti does not pertain to the 730 ecm or the $8D code.

Start a new thread if your going off topic

thanks