I'm going to buy the Zeitronix Zt-2 WB o2 and I'm going to use it to replace my stock NB o2. I'm going to use the simulated NB output on the Zeitronix unit to run into my ECM for it to operate.

I'm also going to use Mike Davis's WB hack. I've already downloaded his hacked AUJP and turned it into a stock AXXF which is what I base my tune off of. The hack will show the WB output in the "Target AFR" variable of the data stream and I already reworked my TunerPro RT ads file to rename the "Target AFR" field "WB Oxygen Sensor" which will show right above the "NB Oxygen Sensor" output on my laptop screen. For this hack I run the WB output into the A3 pin (TPS2, A/D channel 0) on my 730.

I also want to change the programmed "Target AFR" variable in my bin to something more suiting to an N/A performance V8 like a 13.5 AFR instead of a 14.7. Of course tuning with my WB sensor I'll be able to figure out exactly what AFR my engine likes, 13.5 was an example.

Now for my questions:

Anyone else doing this with a WB and this hack? Any comments?

If I change my AFR in my bin from 14.7 to say 13.5, my BLM's will automatically start changing to adjust to the new AFR right? So if my BLM's are dead nuts on 128 now they will go up to like 132 or whatever when I change it to 13.5 AFR from 14.7 right? Then I just have to increase all of my table cells to get them back at 128 which would now be 13.5 instead of the old 14.7 right?

Is any of my thinking wrong?

Thanks!

 

i don't think it works like that. the narrow band o2 is only accurate around 14.7 right? around 450-500 mV let's say. There is a separate part of the bin for Rich/Lean threshold... that's the part i think u're gonna want to change. the reason is that if you set the target AFR to 13.5, and the WBO2 simulates, say... 800mV as an example.... the computer would still think it's too rich since it's past the rich/lean threshold. I think you'd want to change the thresholds so that it thinks 800mV is actually what represents stoich.
I dunno if that's correct, but that's wat i was thinking

 

Everything in the closed loop fueling algorithm is based around stoich, or 14.7:1. You can run a different AFR, but youll no longer have closed loop. I dont think it would eb much of a problem if everything was dialed in real good and you didnt care about saving gas. Id also not use the simulated output. Jsut use the stock O2 and put the WB somewhere where you can easily reach it to remove it when not in use, like the y-pipe. I think putting it closer to the exaust ports may cause it to overheat. I wouldnt want to put anymore milage on a WB then I had to anyway.

 

So if I want to run anything other than 14.7 I would need to run in open loop only and disable closed loop to ensure that the ECM is not adjusting leaner?

I figured that chaning the Target AFR from 14.7 to another number that all calculations the ECM made based on the Target AFR variable would change because the variable was changed. Am I wrong in thinking that? Of course I'd also change the rich/lean thresholds to reflect my new AFR but everyone is saying none of this will work?

One reason I have for leaving in the WB sensor was so that it would give more accurate of a reading at a richer AFR than the NB so that my above would better work...

I have a headers and since everyone says to get a heated o2 I figured I'm in no danger of overheating my WB sensor as you mentioned dimented...

 

actually, why would you want to run anything other than 14.7 for normal driving around? Cuz once you go wide open, the ecm is just gonna go into open loop PE, and change the AFR on it's own based on the values set in the VE table and PE tables right? so just log the readings of the WBO2 while at WOT, and adjust the VE and PE tables accordingly to obtain the correct calculated AFR. That is unless you have some hack that keeps the ecm in closed loop at WOT, and recognize the actual wideband O2 sensor.

 

Because most engines don't run best at 14.7 . I should be more detailed; most engines don't like going rich/lean/rich/lean from stoich. I've found my best gas milage to be cruising around at 16:1 and I don't like the "hit" of going into PE mode. Depends on the driver, some don't care, some do, but the AFR of 14.7 isn't for the engine, it's for the cat converter. No cat, don't bother with 14.7, just tune with a wideband to run open loop all the time. This seems to be the best milage, best responsiveness, best power, biggest smiles.

 

Definatly would be cool to have the afrs be around 15-16:1 at cruise and then have it decay down with increasing load to 12.5:1 or so at WOT. That seems like it would give really smooth performance. But, theres no room for a cat in that equation if your subject to emmisions.

 

is there a way to stay in open loop all the time w/o setting an SES light? I assume the easiest way would be maxing out the values of time and temperature before changing to closed loop. is that right?
I've been considering the WBO2 option a lot lately, but still not convinced that I need it yet. I'm specifically taking a look at the Holley Commander 950 or Accel DFI Gen 7+ either with the wide band option. I think they're just easier to tune that the factory ones.

 

Set the closed loop enable temperature at the maximum value. Flip the malf 12, 44, & 45 codes to off. Do the battery dance to reset the ECM. Done. Can also pull the NB sensor out and set it on the shelf next to the cat & air pump.

A factory ECM is better then aftermarket.

RBob.

 

Better in his case, I don't know. I like the factory ecms for any sub 1000hp 2000+ lb vehicles, but some rev to 14000rpm and in that instance it's a lot easier to use an aftermarket ecm .
BTW, you might want to add the pe-ltd.com computer to the sticky of aftermarket ecms. It has built in coil drivers, real-time datalog, scalable tables, easy to understand % compensations, and a very good race car tool. Even has features like dfco, an engine speed to resume so as not to stall, etc. Pretty advanced hardware, software needs a little more work but it's by far the easiest starting point for anybody that's in a time crunch (racing schedule).

 

Welll. . . taking into account this is a DIY board. . . a n d . . a 3rd gen site. . .

Can't imagine how hot an ECM will run with built in coil drivers. And handling the kickback from a firing coil.

RBob.

 

For use in other then oem cases, they take code changes, but the oem are much better then the aftermarkets, and there's not doubts involved. None of the aftermarkets have 1% of the funds for R+D as GM. Not to mention the destructive testing and taking the abuse of the oems. Not to mention that the ever popular Gen VIs aren't serviced by ACCEL any more. And for $50 you can replace the basic GM box, and not have to worry about turn around times, and parts availibility.

 

They tested it in an oven up to 400 degrees. They have a shop mustang with the ecm mounted 2 inches above the headers on the firewall to prove it's durability. They're completely weather sealed and run rather cool considering the coil drivers. I don't LIKE the idea but it works well for them.
Grumpy, I'm hoping you know I know the advantages of a factory ecm over aftermarket. The software GM uses is NOT intuitive for somebody just entering EFI.
I can think of a few friends with thirdgens that would be better off with an aftermarket unit as opposed to the DIY route.
You talked about Accel not supporting older ecms. I don't believe GM has every given tech support for the DIYer . This board is the only good tech support for the factory computers.

 

Innovative requires it to be ON when car in running as you are aware. next week it may be wired to heat up with IGN on per the instructions Innovate provides. Mine is behind collector in exhaust pipe , a mirror image of the NB 02. I cant imagine removing it as the cable is through the firewall and passing through my dash. it is comfortable sitting on passanger seat. looks like i will run it till it pukes. anyone have a breakdown of it yet? wonder what the weak link may be?