05/31/2006
Well I finally found the time to "attempt" to drop the Y pipe and install a wide band O2 sensor (WBO2). The WBO2 has a 0-5V range compared to the OEM NBO2 of 0-1V. Only to find I did not have the correct gender on the cable ends or chassis mount connector. Of course it's a rare 9 pin DIN of which only two wires get used (for now). So now it's attached to my trusty Fluke DVOM and sitting on the seat. Cable is ordered and will be here tomorrow.
Anyways first off I need to say that in the past I have disagreed with certain SCT dealers ideas on what the best (commanded as it turns out) AF mix in open loop (OP), feeling it was too lean. My butt dyno (BD) could tell that the tune needed to be richer but it has extra sensor area. The truth be the known is the SCT commanded AF mix were close, always were mathematically. But the OEM MAF tables were way out as far as best calibration, very low in resolution and set to work for any SHO V8 motor I guess.
Now I do have a very free breathing pre-TB 4" intake with filter in the fenderwell set up. Got some nice smooth and somewhat insulative silicone hose for the transitions. But the engine needed a lot more fuel than what was being commanded to be delivered. The tables needed to be set for rich rich (still leaner than OEM though) to get the actual desired AF mix because of the restrictive OEM MAF tables. And I don't have those butterflythingies. Which may be the reason the OEM MAF table was so lame, but still low res. Kind of like the difference between a 1 Mb photo and a same dimensional sized 100k photo, as an extreme example.
Loaded a Cobra 99-01 80mm MAF table in. Improved especially with the broader range of load=better resolution, +30%. This was near the mark at the correct AF mix of low 12s under max load and +5k rpms, certifying my BD. But the commanded values were still off as it was producing a higher AF mix than commanded. Multiplied the MAF table a bit to increase the air and it worked out good. But still was going too rich at high rpm compared to the commanded value. So I split the table up into three ranges and used a higher multiplier down low than mid or high rpms. Seems as good as I can get by watching the road, the Fluke and the laptop while doing 0-120 runs.... But the commanded values are now producing near the mathematical values which is the goal.
I need to get the WBO2 connected into the Xcal2 so the numbers can be logged. This is needed to fine tune it all. The MAF is the primary sensor that the PCM code is built around. Then I will go in and fine tune the affected parameters because of the increased range of data. Got to get it set up for my Casey's 89 octane corn gas you know....
Paul
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Where did you get the wideband and what did it cost?
http://www.openecu.org/index.php?title=Main_Page
Could something like this be useful?
k mier
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I know Josh has them - http://www.shonutperformance.com/
(under Misc ,header)
Not sure if the price is 'great' , but not bad . A little hunting may yield better.
Rick B
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I got mine from www.vmptuning.com it is an Innovate Motorsports brand, w/Bosch sensor. Very good support forum there too. ~$200.00.
http://www.innovatemotorsports.com/index.html
http://www.innovatemotorsports.com/forums/
Paul
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Paul,
Glad to hear you finally put a wideband on that sucker. ;)
Just a few FWIW thoughts in response to your post:
When comparing (or modifying) MAF curves, keep in mind that there are
reasons behind the actual structure, resolution and layout of the factory
MAF transfer functions. Case in point here would be the lower-end of most
factory transfer functions, where the greater number of data points gives
the EEC a higher degree of accuracy in idle and low-RPM situations when
calculating the actual air-mass. Furthermore, since the EEC is always
performing complex interpolation routines against the MAF curve to arrive
at said actual air-mass values, the positioning of your data points matter
just as much as (if not more than) their quantity.
In addition to the MAF transfer function, keep in mind that there are also
several other key players within a calibration that can affect/upset the
"commanded vs. actual AFR" balance. The first area I would look to is your
fuel multipliers (WOT Fuel Multiplier, etc.) - have you disabled these
functions (by filling their Y-Axes with
1's) or are you still running the factory values for these fuel-modifying functions? If the former is your answer, I would then
Adam
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Adam
Thanks for the tips as usual.
The data transfer points (counts in SCT terms) came from the SCT 99-01
Cobra 80 mm value file. I only adjusted the actual value of MASS / # clock tics. Attached is a picture of the OEM vs. the SCT value file MAF transfer function table.
The WOT fuel multiplier are all 1s. And the adaptive control for the base fuel table is turned off.
I did get some form of software with the Innovate LC-1 setup. Haven't used it to any extent yet. I certainly will look into the EEC Analyzer though.
Paul
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Not sure WTF it is, but if Paul sez it's a good thing, who am I to argue???
U.L.