I have some strange results now that I'm running Open loop.
I like someone of you gurus will chime in:
Before to running OL:

I have a Zeitronix WB with the sensor working as NB simulator for CL.
before to install the Zeitronix the BLM were all 126-128 (with stock NB sensor).

I installed the Zeitronix (always running closed loop) and the reported BLM were allways 126-128-130.

With the Zeitronix connected to read real AFR, I noticed that all readings were very near 14.7 (it was bouncing from 15,5 to 14,0). (BLM always 126-128).
Usually I read about people scared by the fact that running CL (with ECM correction to stay in 14.7 range), the reported AFR was very lean (or way different from 14.7).

So, this is not my case.

With this good starting point, I tried to lower and then raise the VE values.
The BLM's changed accordingly and the AFR stayed near 14.7(sometimes an hair more , sometimes an hair less than 14.7 . I ended with the same VE value (for part throttle no PE) as before.

Then I tried to running OL.
HERE the surprise.
The AFR in the WB is near 16:1 - 17:1.
Now the car is running on the VE values only (supposed to be correct because the 14.7 value reported by the WB in closed loop).
What do you think about this strange thing?
Thanks
-Beppe-

 

I add: I swithched back to Closed loop without changing VE tables.

I have 126-128 BLM values and the WB averges 14.7 (bouncing 15.5 to 14).

I swithched back again to OPEN loop without changing VE tables.

WB says: 16:1 - 17:1.

 

Check the data log for what the commanded AFR is. It may be that it is commanding a lean AFR which in turn is what you are seeing.

Remember that the commanded AFR is part of the calculation for the injector PW.

RBob.

 

FWIW:
I still have the DIY WB running in mine, just for logging & tuning (not ECM control).
Compared to the NB, it has always read ~14.7 at warm idle and light cruise. There is no differece NB/WB.
Remember though, the DIY WB has only the full-range output (0-5v) not the simulated NB signal.
I wondered if the simulated signal was accurate enough to run the ECM, but haven't tried one yet.

HTH
DRJ

 

PS - I havn't time to look it up just now (and working from memory is iffy for me)
but there used to be a table somewhere in 8D that added 0.1v to the O2 value or
L/R point - was it during CCP enable, or smog pump enable?? I don't recall the
specifics now, but it might be something for you to look at.. Just an idea...

HTH, DRJ

 

Also, I found a bug in the '165 XDF for the Open Loop enrichment tables. It was always offset by some amount, like 8% (fading memory on this). I posted the fix on here some time about 6 months ago if you want to check it out.

Most people saw the "8%" and made it 0%. This caused it to actually be -8% from 14.7.

It's possible that your XDF has that too, as the open loop percent table is probably the same.

I'll dig around to see if I can find that.

 

Found! (if I correct undersatand what you are saying)
the tables in 8D are:
loop Open % change AFR vs. map and
loop Open % change AFR vs. temp.

Some time ago, in order to cure a rich open loop condition at start up I reduced these tables to 1/3!
I thought: " I reduce the % added to OL", It will ADD something less.
I thought that it was continuing ADDING fuel (less than before, but still adding fuel OVER the theoretical 14.7:1)

Now reading this, the 2/3 removed is enought to let it run lean, and the stock values on the tables are only a bit rich than 14.7.

The PW calculation ( Rbob is right) start from the commanded AFR, and I observed thatin the Datamaster log is more than 14.7 .
-Beppe-

 

I had a rich open loop also
and used the same open loop temp tables, I noticed tunercat and
tunerpro had different values in them 730 8d open loop afr vs temp, same bin
Why in tunercat can only change them buy 1%






TunerCat
9.77
9.77
9.77
9.77
9.77
9.77
9.77
9.77
9.77
9.77
9.77
14.84
19.53
29.69
59.77
94.53
TunerPRO
51.1
21.1
10.9
6.2
1.1
1.1
1.1
1.1
1.1
1.1
1.1
1.1
1.1
1.1
1.1
1.1

 

The .1v (100 mv) offset is for, when the smog pump is blowing air into the exhaust manifold, affecting the O2 readout. O2 readout + 100 mv = corrected O2 mv reading.

Cylinder AFR is corrected, O2 reading is cylinder burn + manifold burn (due to smog pump air injection). The .1v adds back in the fuel removed by the smog pump. Other wise you would get a "false lean" O2.

 

In the '165, the CORRECT conversions for Open loop are

Vs LV8
0.390625 * X + 0.000000

Vs Coolant Temp
X/2.56 - 13.67


The (-13.67) is what makes it all work right.

Maybe try that... and report the results.

 

I have this doubt some time ago...
see post #13 here:
https://www.thirdgen.org/forums/diy-...tml?highlight=

-Beppe-

 

Yes, thank you, that was the table entry of which I was thinking. I hadn't looked
in that part of the mask in years. I made the suggestion to try and help the man
from Milano - he was the one looking for ideas.

Thanks again for your contribution.

DRJ

 

Thanks Doctor, Thanks Pandin.
The .100 offset is managed on my chip. (I have the A.I.R.pump removed).
-Beppe-