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Flex fuel OS, Stoich parameter


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In HP there is this:


and in PCMTEC the equivalent is this:


I'm looking at a well behaved HPT e85 tune to get some pointers on getting my cold start better. It's quite impressive what he achieved without touching many tables at all. Obviously the stoich adjustment to 9.8:1 takes care of most of the fuel scaling in one hit. In PCMTEC I have this set still at 14.6:1 and it is not included in my flex parameters. 

Naturally, we have this for the flex configuration in the custom OS, auf100014


The question I have, does the above table scale the fuelling in the same way that adjusting auF0117 to 9.8:1 would if I was running a fixed e85 tune?

I'm reading the e85 thread here for ideas and seeing some huge increases to crank fuel and crank fuel multiplier so I'm leaning towards that the fuel is not scaled with auF0117 like it would be if I was running a fixed e85 tune and dropped auF0117 to 9.8:1.



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3 hours ago, Roland@pcmtec said:

Due to the poor atomisation at cold temps you need up to 400% fuel enrichment on cold start in the first few pips

In the f150 at e100 -30 deg they command 1400% more fuel on cold start. 

That's lining a few things up with what I'm seeing. Thanks.

3 hours ago, Roland@pcmtec said:

auf100014 replaces auF0117 in the custom os. The correct stoich for e85 is 9.765 not 9.81

Got ya.

Thanks Roland.

Edited by hjtrbo
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Now that a night of sleep has taken place and the caffeine is running through me I realise how stupid that question was. 

Of course the fuel is scaled with the flex stoic parameter. Otherwise the fuel trims would be way out when going between the fuels. Idiot. 

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43 minutes ago, Puffwagon said:

I've changed the stoich value in the tune and it does diddly squat.

Which one did you change? 100014 or 0117.

BTW there is no need for me to change anything. It's all fine. Just curious. 

Got it to start at 10degC this morning. Progress is good. 

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2 minutes ago, Puffwagon said:

I changed auF0117.

If you want it to start good on E85 change auF0180 to 0.2 lambda up to about 50c then lean it out after there.

Ta, that's where it's heading. It was stock by the previous tuner with a small crank PIP table change. Have wound up the 0 column in the crank PIP multiplier and working crank lambda down 0.1 at a time each morning before work. Currently cranking at 0.5. Next tune for tomorrow has it at 0.4. Open loop for 45 seconds. Deleted all the cat spark warm up. Have a 200rpm cold crank adder and cold cells ect idle adder decaying away over 30 seconds. Idle air and dashpot is spot on. Can blip the throttle straight after starting with no hesitation and put it into drive and off I go straight away as well. No change needed to pump shot.

I'm close. 

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On 11/11/2021 at 9:51 AM, Puffwagon said:

If you want it to start good on E85 change auF0180 to 0.2 lambda up to about 50c then lean it out after there.


Starts better than on 98. Lights off instantly at 12degC.

Still a few very minor niggles to sort out but it's a winner. Have gained enough knowledge to tackle the inevitable revisit in winter when we get down to 0degC.

Went with crank spark at 15deg for shits and giggles. Seemed to like it.



50.tec Main Idle Tables.xlsx

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  • 4 weeks later...

A few tune updates. Fixed up the MIL light issue I spoke of in another thread. Pretty sure I've got all the dodgy shit out of this tune now. I sure would appreciate someone seeing if there is any gremlins / gotchas left in it that I haven't learned about yet....

Running so well on e85. 98 tune will need a touch up now as I've pulled tables out the flex tune. Just waiting for winter now to tackle the 0 deg e85 starts. Implemented boost by gear just to help out 1st gear a bit. Ute specs, F6 turbo with flapper mod, mandatory bolt ons / springs etc, standard dump, 3.5" single cell cat pipe splitting into 2 x 2.5" cat back. Flat 14psi on 98 and flat 16psi on e85. Looking to take it up to 19psi on the same timing, road tune.


72_In Car_e85 Solid Roll Back Point_98 Will Need A Touchup.tec

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Yes, my ute is a FG Mk1 XR6 Turbo. I tried out a few different ZF strategies and settled on the FG Mk1 F6 strategy. There is a couple of different ways to achieve the same with regards to changing calibrations but in my case I had success grabbing the F6 strategy from the create stock wizard and just dumped the whole thing into the box. Then adjusted auF1692 to match the ZF cal value in table ZF03987. Trans stays in limp mode if the calibration values don't match. Then I read the whole tune out again from both PCM and TCM so I didn't have a whole bunch of red compare marks all over my ZF section of my tune.

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