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sutyak 09-08-2012 11:13 PM

Formulas needed
8 Attachment(s)
I need the formulas to calculate 1) final spark and 2) load.

I have these in a guide somewhere but can't find them since I moving twice in one year. [scratch]
Not having my tuning manuals has been a pain.

iminhell 09-09-2012 04:46 AM

I don't know them off the top of my head.
But why do you need them?
Both can be logged very easily and don't require math.

sutyak 09-09-2012 07:59 AM

8 Attachment(s)
I am logging these calculated values and they are off. I need to verify the output by going over the inputs.

1turbofocus 09-09-2012 09:00 AM

Do what ? If there off change them , set the load to where you going to be running for the amount of boost then make the change in the timing to what the engine tells you it wants not what you think it should be


iminhell 09-09-2012 04:29 PM

Post a log or something.

I don't quite understand what you mean by load is off.
I do know that adjusting engine displacement will change load. As will changing the "correction for max air charge".

But a log would really help.

sutyak 09-09-2012 04:56 PM

8 Attachment(s)
Setup: 10psi GT2871r 2.0 Duratec, Cossie-type IM, 60lb injectors, 3" blow-through MAF, 50/50 meth injection.
I changed the intake manifold and injectors at the same time, so now I'm trying to troubleshoot two things at one time. What I'm seeing is the load DROPPING after about 690 MAF counts, and I'm clearly having fueling issues about that same spot.
AFR goes from about 11.0 and climbs to 14.0 where I let off.
Knock sensor is not pulling timing, but by the same token the total spark does NOT match the commanded spark in the BKT, but I can't figure out why the spark values are off.
Fuel source is 5 as expected and spark source is 2 also as expected.
The injector pressure drop is 36.99 and ends at 41.875 when I let off.

I clearly don't have the fueling set up correctly, but not sure where. It is as if it is ignoring the MTF after around 700 counts counts or so. I have the MTF quite over-compensated as you can see in the screen shot, with no affect.
I'm using the advertised injector values for these 60lb Seimens injectors and I've checked multiple places. I don't think the fuel is being properly scaled for the given psi, but need some help determining why.

The reason I asked for the formulas was so I can backtrack and see why the load is dropping instead of increasing and why the final spark value doesn't match what I'm commanding.

Screen shot of load falling off. This is at a steady 10-11psi, meth spraying.
Load - yellow
MAF counts - yellow
AFR - red
Fuel pressure - bottom line
Lots of other things logged but I'm not cluttering up the screen shot.

Injector scalars:

The over-compensating MTF

Displacement is stock and intake manifold volume is also stock. No MAFia.

Prior to the intake manifold and injectors the load would rise to 1.5 and fueling was no problem. The ONLY changes have been for the injectors and tweaking the MTF. Also the meth injection, but it does this regardless whether it sprays or not. Spraying drops the intake temps and the AFT around 1 point. I was spraying in this log. The leads me to believe the injector values are not correct.

Low slope (from value file)

High slope (from value file)

iminhell 09-09-2012 06:10 PM

You can't overcompensate with the MTF. That will reduce the fuel, and probably load.
That is step 1.

What's happening is that it's now harder to get to those flows and I'd bet you aren't hitting as high in maf counts as you should be. You should instead adjust the base fuel table.

I've read a bunch of posts, mostly self tuned Mustang guys, who say that to tune the MTF they do a log just sitting in their driveway revving the engine slowly up to about 500 counts and adjust vs STFT's from there.
Now while that is correct in part it isn't the full story. You can actually go all the way to 1023 counts by this method so long as you stay out of WOT.
The higher you can flow part throttle the better. What it does is makes it easier to get to the base fuel table, and therefore much easier to tune WOT fueling.

I'm just starting to use LL II to go through logs but man is it easy and quick once you have it setup right:


Set up the same as your counts, not mine

Gives you a easy way to see if things are working as they should. That is, are you using the base fuel table correctly or not. In this case I am.

You can open any previous log with Live Link II. You can't datalog with it though. For some reason it doesn't like the Focus and it also will only log with a XcalIII.
Download link -->

Or at least that's my take on it ...

sutyak 09-09-2012 09:38 PM

8 Attachment(s)
You must be talking strictly about N/A engines, because there is NO way to hit 1023 MAF counts sitting idle with a turbo car, and you shouldn't. I think I might hit 300 free-revving like that.
Also, you do not fudge the base fuel table to get a desired AFR. The MTF does directly affect fueling. I'm not sure where you got that it doesn't. It is the primary table for the computer to know how much air is flowing (by what you told it) so it can use all other variables to produce the desired lambda set in the base fuel table.

There are many other factors you don't have to deal with being N/A. What I need is a full equation showing how load is produced so I can back-track across all my set variables to determine why the AFR is off. Most importantly I need to review my fueling settings with someone who has tuned a turbo car with these particular injectors.

sutyak 09-09-2012 10:23 PM

8 Attachment(s)
I'm going to log voltage tomorrow to see if the value file I used for the 60lb injectors screwed up the injector pulsewidth offset.
I see that my previous setup with 55# injectors did not modify these voltage tables at all, and I had no fueling issues with those.

Any other suggested values to log regarding fuel are welcome.
I'm currently logging "fuel_rail_pr_psi", "fp_duty_cycle" and "ini_pressure_drop". For the record fuel pump duty cycle isn't going above 0.32, except at a rather odd time during decel when it hit .750 for a couple seconds.

1turbofocus 09-10-2012 11:41 AM

I dont know why it is so hard for you to ask for help ? doing it here with steady logs and not seing the tune file is a waste of time and all speculation nothing more , guessing isnt going to help

I also agree you should never rev an engine to hit max MAF counts sitting still


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