Lowest Load value doesn't seem low enough

[ReadyXB]

The 1125 is factory equipped with a MAP and baro sensor. The MAP sensor attaches via a vacuum tube to the throttle body. Part# P0508.1AM.

[ReadyXB]

I checked BUEOD (feature not even available), BUEYD, BUEZD, BUE1D (XB9), and BUE2D EEPROMs and the feature "TPS and MAP Load Setup: Enable TPS/MAP load feature" is disabled, and the "MAP to Load Table MAP Axis" tables are empty.

All of this was done on XB EEPROM data. Does anyone have a stock 1125 EEPROM (any year) they can post for me to check?

[Negative]

Ha ! ... very nice work ReadyXB !! ... Guess my assumptions were close enough for government work at least ... lolol :)

Good **** !!

[ReadyXB]

I am slowly working on a DDFI-3 setup for my XB that will utilize the MAP sensor and TPS to determine load. It is quite a project, though.

I want to do the same thing! I think you're right, though; it will be a challenge.
I also plan to put 2010 XB12R headers on my 2008 and add the second O2 sensor, but that will come later.

[EricZ]

I'd like to think you're right, ReadyXB, but I have yet to see a 1125 eeprom that uses the MAP sensor signal for anything more than injector timing. I meant that they don't use them to determine load....fueling or ignition timing.

[ReadyXB]

No, I agree! I DON'T think anything except TPS is used for Load. I think all other adjustments are made -after- the Load/RPM lookup. That's what my investigation and reading has found so far.

...Which is why I can't figure out what ich meant when he said I was wrong about TPS alone being used for Load. He said "Not true for DDFI-3". That statement is what sent me on this side-path trying to confirm what he said.

ich! Help! This is killing me. What did you mean?? :) My brain needs peace!

[ReadyXB]

So I have an update in case anyone was following this thread.

It took more time and investigation, but I have found two ways to artificially affect my Load value - at least the base/reference value.

1. "Throttle Position Sensor Reset Voltage"
This correlation should be no surprise
This is the value that gets updated when you do the automagic 3-step throttle twist on DDFI-3.
I modified the EEPROM value directly to not only confirm but to also see the trend.
- increasing TPS reset voltage values causes LOWER base load value
- decreasing TPS reset voltage value causes HIGHER base load value.

FYI: I had to temporarily disable the "Enable TPS auto zero feature" flag. Fortunately it didn't take long to figure out I needed to do that. I had been twisting the throttle so much during this investigation that I on many occasions saw the Load mysteriously change. After brief frustration, I realized what was happening and cleared the flag.
Sanity check confirmed.

2. "Idle Air Control Throttle Position Adjustment" table
This one was surprising at first but it does make sense, and it was worth the effort of experimentation because I learned something!
As with TPS reset voltage value, modifying this table will artificially change the base Load value.
My default is:

Steps | TPS 8-bit (not 10)
--------------------------
10 1
20 2
30 3
40 5
60 7
90 11
140 17
200 17

- Increasing the values in the TPS 8-bit column resulted in HIGHER base Load value.

Having said that, it's important to note that all I've done is alter an initial "calibrated" reference Load value. I haven't made any meaningful change to the run-time Load value calculation since the TPS-IAC table is static.

--------------------

So if I am deducing accurately, both TPS and IAC do affect the Load (on DDFI-3). In hindsight this makes sense because throttle position and IAC position both affect RPM. Higher RPM, whether due to Throttle Position or IAC position, affect the amount of air entering the engine. More air means a corresponding increase in fuel is needed, and this is accomplished by changing the Load value. And, DDFI-2 has no IAC, so only TPS affects Load in that case.

ich, is this correct?

[ich]

weitgehend ja.

[ReadyXB]

weitgehend ja.

Thanks, ich. If google translated properly, you said I am "mostly" correct. Mostly correct is not fully correct, and my personality won't let that go. So what else am I missing?

ECMSpy Q&A, Q18 says

The TPS-8bit value, which represents the Y-axis in all DDFI and DDFI-2 maps, has been renamed to 'Load' (rear cylinder) and 'Load1' (front cylinder, where applicable). DDFI-3 won't use the TPS input on it's own for calculating load, but is capable to add MAP sensor input to this calculation also.

Capable - ok. But after looking at a stock 1125 BUE2D eeprom (thanks to a helpful forum member), the flag "Enable TPS/MAP load feature" is Off, and the Front/Read MAP to Load Tables are empty.
Capable - yes. Enabled - no. Unless there is some other way of enabling MAP to factor into Load besides that flag?
Without an 1125 of my own (would be nice:D), there's a limit to what I can tinker with.

I am eager to learn and have done due diligence. There is a lot of misinformation around, on this forum and on others. I don't want to perpetuate misinformation or mislead anyone. Misinformation can and has cost people money.

If you are unsure about the inner workings of Load, that is fine! But if you have more knowledge, I would appreciate anything else you can share to help guide me. Thanks for your help so far.

[Negative]

Woo man ... There are soooooo many more changes to DDFI 3 than I thought ...