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FuelCycles

New Member
Oct 9, 2019
9
Katy, Texas
Hello all,
First time on E85, did a quick 3rd gear pull at 19-20psi. Let me know if you see something concerning. Throttle possition looks like its closing towards the top, not sure why.
E85, 750cc PI, split second controller, 15psi hobbs switch, stage 4 Fuel it lpfp, MHD.
 

nyt

Private
Sep 15, 2019
28
Bit strange, your throttle position plot looks more like WGDC and your boost holds flat in the graph even after you started letting off the accelerator. Maybe a bug in the grapher?

Otherwise, you have timing corrections. Should look into why. Can't see exact AFR since for some reason there's no precision in this graph for that.
 
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Reactions: doublespaces

CNM135i

Private
Nov 14, 2018
37
Make a log without wheelspin and where you dont let off the throttle - use a higher gear.

This log integration in the thread is genius!!!
 

FuelCycles

New Member
Oct 9, 2019
9
Katy, Texas
Bit strange, your throttle position plot looks more like WGDC and your boost holds flat in the graph even after you started letting off the accelerator. Maybe a bug in the grapher?

Otherwise, you have timing corrections. Should look into why. Can't see exact AFR since for some reason there's no precision in this graph for that.
If you click lambada it’ll show AFR. Not sure why the timing correction, brand new ngks gapped to 18 and bimmerlife coils.
 

White Sands

New Member
May 21, 2019
7
You should be concerned with those STFT's, both banks pegged at -34 at full boost. Your running extremely rich
 

doublespaces

Administrator
Oct 18, 2016
7,945
AZ
I didn’t know if that had anything to do with the PI
Not directly, but when your air fuel ratios go rich the ECU will try to lean out the fuel trims(and vice versa for being lean). This is why some fuel systems can receive criticism because fuel can pop in or out and the ECU is otherwise unaware except for how the air fuel ratios look after the fact. If you noticed, there is a check box now in MHD for PI coil kill. This is because DI can be stopped in a cylinder but the PI is still spraying as it is not controlled by the ECU. And since the coil for that cylinder would fire regardless, you'd get this super lean combustion that was causing engine problems. Someone can feel free to clarify this if necessary.

But more or less, your engine is getting fuel dumped on it like a mop bucket and it has to react using the o2 sensors. This means there is some adjustment needing to be done between your AIC and MHD tune. STFT are bound to fluctuate but the closer they are to 0 the more wiggle room the ECU has to adjust for something unexpected.
 

iminhell1

Corporal
Jun 17, 2018
202
^ correct.

Pull 10% fuel and go from there. Once you have STFT's moving and not maxed you'll have an idea of how much you need to add/pull and where.
Also keep in mind there is no compensation for pressure changes ... once the trim maxes you LPFP goes to shit. So you need to be close to 0 to add wiggle room there also.
 

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