FN346 ....PIP Multplier Larger/Smaller values?

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skunk
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FN346 ....PIP Multplier Larger/Smaller values?

Post by skunk » Sat Aug 04, 2018 1:09 pm

Been trying to do some reading up on this function killing time at work. I am trying to figure out what exactly it's multiplying. I know cgrey has spent alot of time and posting his Hego findings but I can't seem to find if altering this value has any benefit or even which way does what.

The reason I am asking has to with my setup where 1 hego is used for both banks via crossover. At low rpm like idle, I can use the trends option in BE an watch how Lambse and Hego interact. With all Hego parameters in stock form, I have a lot of jitter around the crossover voltage. I have experimented with bias which is my current solution to hold the switching back a little longer/slower. I have experimented with cutting the delay as much as half which looks promising as a waveform but I don't feel it's enough time to register the fuel change properly.

This brings me to the PIP Multplier. I am hesitant to make a change due not knowing which way to go with it. I understand the relationship of Bias/Amplitude on that function but I don't understand is what part of the pip routine shown in BE the multplier acting on. Will changes here basically yeild the same result as the delay table? I keep thinking if I reduce the multplier, it should reduce the number of expected PIPs before the changed fueling is registered without altering the minimum of 2 fires per cylinder. Going from memory here...if I interpreted correctly, depending on bias/ptpam the expected PIPs (2) will mutiplied anywhere from 2-15 times. ( Someone correct that range if I'm way off)

I do plan on experimenting with exaggerated numbers to see what results, in the meantime if anyone has a grasp of the function, please chime in.

Thanks
John
1987 Turbocoupe.
A3M1/A9L, BE/EA, Tweecer RT.
306,Single Turbo, Ported E7's, Ported Stock Intake, 42lb Matched Green Tops, PMAS 3" Blow-Thru Protube (42# supercharger calibrated),T5z, 3.73 gears
..... Nothin Fancy.......Just something to keep me from the honey-do list.........

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Re: FN346 ....PIP Multplier Larger/Smaller values?

Post by cgrey8 » Sat Aug 04, 2018 3:37 pm

I have to admit, I don't recall ever messing with this function. And when I compare my tune to either an X3Z or A9L, they are the same. So I guess I never messed with it.

What I'm confused on is what the absolute value of Bias/Amplitude gives me and why that relationship would have an affect on the amount of time to care about passing before allowing the system to adjust. That seems far more like the job of the HEGO Delay which is why I focused all my efforts on the other HEGO related functions, FN339, FN342, and FN344. I was able to accomplish everything I needed by tweaking those three methods in concert with the HEGO Bias, Delay, and Amplitude.

For those not familiar with any of this, the HEGO Bias, Delay, and Amplitude are the high level adjustments that the vast majority of people make changes to and get success with. I was never satisfied with the underlying functionality, so I had to go deeper into those 3 HEGO functions, which changes the algorithm a bit more. Unfortunately, that alters the meaning of the values in the table making it impossible for anybody to compare my tune's table values to their own since my table values are adjusted based on my function changes as well. The only thing I remember I didn't like about the underlying algorithms was the Ramp Rate. I modified that heavily to get more responsiveness. But I was probably able to do that because my setup doesn't have a significant amount of noise in the HEGO values. They jitter around a little, but not nearly as much as it seemed the stock logic expected them to and thus was filtering for.
...Always Somethin'

89 Ranger Supercab, 331 w/GT40p heads, ported Explorer lower, Crane Powermax 2020 cam, 1.6RRs, FMS Explorer (GT40p) headers, Slot Style MAF, aftermarket T5 'Z-Spec', 8.8" rear w/3.27s, Powertrax Locker, Innovate LC-1, GUFB, Moates QuarterHorse tuned using BE&EA

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Re: FN346 ....PIP Multplier Larger/Smaller values?

Post by skunk » Sat Aug 04, 2018 5:22 pm

Thanks for the response Chris. I am now looking at it and have decided I have no idea how to calculate the BIAS/PTPAMP. I have always looked at it as a sum. If that's the case, based on stock values, anything with a zero or positive value in the Bias table is going to fall on the maximum multiplier of 15.188. It isn't until you start moving further into a rich bias greater than -0.0286 where the multiplier begins to get smaller between 7.625 to just above 5.125. If its BIAS divided by PTPAMP....I cant wrap my head around it. That makes anything negative to zero a multiplier of 1 with only positive Bias moving to higher numerical multipliers ( of which there aren't too many). My brain isnt firing right now...… If you can add some clarity I appreciate it otherwise guess im going to have to get into the document

If you want to see something kinda odd with HEGO Bias and try to figure an answer as to why they are so different..... take a look at the GUF1 A9T vs C3W1. The main difference is the A9T above 20 LOAD goes into a heavy deep BIAS of around -0.1200 for all cells. Its like they made all HEGO functions into 2 data points. For the most part the bins are the same. The main stand out is timing. Fuel is leaned up top but its put back in with a WOT multiplier that bares resemblance to the A9L.

Thanks for any and all input
John
1987 Turbocoupe.
A3M1/A9L, BE/EA, Tweecer RT.
306,Single Turbo, Ported E7's, Ported Stock Intake, 42lb Matched Green Tops, PMAS 3" Blow-Thru Protube (42# supercharger calibrated),T5z, 3.73 gears
..... Nothin Fancy.......Just something to keep me from the honey-do list.........

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skunk
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Re: FN346 ....PIP Multplier Larger/Smaller values?

Post by skunk » Sat Aug 04, 2018 5:40 pm

Forgot to add....I do have a theory in my mind for it but without knowing how to interpret the given info, it doesn't make sense.

I really need to look at a bin for the 5.0 trucks that used a crossover. I assume they we're mono Hego systems.

John
1987 Turbocoupe.
A3M1/A9L, BE/EA, Tweecer RT.
306,Single Turbo, Ported E7's, Ported Stock Intake, 42lb Matched Green Tops, PMAS 3" Blow-Thru Protube (42# supercharger calibrated),T5z, 3.73 gears
..... Nothin Fancy.......Just something to keep me from the honey-do list.........

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skunk
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Re: FN346 ....PIP Multplier Larger/Smaller values?

Post by skunk » Mon Aug 06, 2018 2:06 pm

Quick update...… just getting started but so far it appears we may need to look at FN346 more as a window size. The smaller the window the faster or maybe more accurately, Larger the reaction. Similar to using a rich bias which also forces a smaller window of expected pips. In my case where pulses are doubled and somewhat smoothed passing through the turbine, a smaller window appears to do the trick correcting what looks like a very lazy HEGO......too early to commit 100% but im going to run like this for a little while and see.

John
1987 Turbocoupe.
A3M1/A9L, BE/EA, Tweecer RT.
306,Single Turbo, Ported E7's, Ported Stock Intake, 42lb Matched Green Tops, PMAS 3" Blow-Thru Protube (42# supercharger calibrated),T5z, 3.73 gears
..... Nothin Fancy.......Just something to keep me from the honey-do list.........

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skunk
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Re: FN346 ....PIP Multplier Larger/Smaller values?

Post by skunk » Mon Aug 06, 2018 4:26 pm

Starting to rain so here are a couple of screen shots. All three sitting at a hot idle.
Yellow= HEGO
Green= Lambse
Pink= AFR

1. FN346 stock, zero bias: You can see lambse is very casual with AFR seeming to favor lean until the slow jump/ramp finally gets it to switch. Its slow in both directions.

2. FN346 stock, heavy rich bias: Basically same as #1 except its a very slow jump/ramp to lean then a hard drop to rich.

3. FN346 cut in half, zero bias: aside from the graph showing more data compressing things some, the AFR seems to follow Lambse more closely with quicker more defined jumps/ramps in both directions. It will need some adjusting to reduce spikes.

I suppose cutting the HEGO delay in half or modifying the jump/ramp parameters would accomplish the same thing. Using FN346 intead appears to provide a means to control the size of the window allowed for changes to take place. This may be a better option to play with for those with log tube headers. Keep in mind this is all conjecture, I am speculating and making assumptions......lol you know what happens when you assume, right?

Heres the screenshots......sorry if they end up a little large.

John
no bias stock.jpg
Zero Bias Stock FN346
no bias stock.jpg (142.43 KiB) Viewed 1139 times
rich bias stock.jpg
Heavy Rich Bias Stock FN346
rich bias stock.jpg (140.16 KiB) Viewed 1139 times
no bias modified.jpg
Zero Bias Half FN346
no bias modified.jpg (169.75 KiB) Viewed 1139 times
1987 Turbocoupe.
A3M1/A9L, BE/EA, Tweecer RT.
306,Single Turbo, Ported E7's, Ported Stock Intake, 42lb Matched Green Tops, PMAS 3" Blow-Thru Protube (42# supercharger calibrated),T5z, 3.73 gears
..... Nothin Fancy.......Just something to keep me from the honey-do list.........

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cgrey8
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Re: FN346 ....PIP Multplier Larger/Smaller values?

Post by cgrey8 » Mon Aug 06, 2018 5:41 pm

Interesting. I minimized my Jump functions to almost nothing and let the majority of my adjustment be from the ramp rate. I reduced my amplitude by over 1/2 and that had a similar result. Oh the other thing I did was reduce my HEGO switch point voltage down to .2v so even a slightly rich bias still results in a relatively lean mix, which is what I wanted for better fuel economy while in CL. Once the engine is warm and running stable, I'm in MFA which REALLY leans things out. While running Closed Loop, the WB is quite accurate and in line with the HEGO values. However in MFA mode, I'm targetting as high as 1.10 and getting 1.08-1.15 at the WB. Even though LAMBSE is stable, the WB is bouncing in that relatively wide range as though each cylinder is that far off. I think some of that is because I also run EGR. During MFA, there's an excess of oxygen in the exhaust. So recycling EGR puts back into the intake oxygen that the computer isn't counting on. That oxygen was measured the first time through the engine, but it wasn't expected the 2nd time. So I think that extra oxygen creates some instability in the actual cylinder AFR even though LAMBSE is being held stable by open loop MFA mode.

Early on in my use of MFA, I realized that I couldn't get that lean because the EGR was throwing things badly. About the most lean I could get things was maybe a target of 1.04-1.05 and that was resulting in wild swings between 1.04-1.15 at light load conditions. So I had to 1/2 EGR contribution at low RPM/loads during MFA mode... and there's a table to do just that. With about 1/2 the EGR flow at 1200/20% Load, I was able to get a leaner and more stable cruise which is particularly useful on the daily commute where the engine see's this RPM/Load most of the drive. Moderate load cruise was able to tolerate a .8ish multiplier. Higher RPM/Load conditions can tolerage much greater amounts of EGR without ill effects.

So I find it interesting you were able to use FN346 to attain something similar to what I was endeavoring.
...Always Somethin'

89 Ranger Supercab, 331 w/GT40p heads, ported Explorer lower, Crane Powermax 2020 cam, 1.6RRs, FMS Explorer (GT40p) headers, Slot Style MAF, aftermarket T5 'Z-Spec', 8.8" rear w/3.27s, Powertrax Locker, Innovate LC-1, GUFB, Moates QuarterHorse tuned using BE&EA

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skunk
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Re: FN346 ....PIP Multplier Larger/Smaller values?

Post by skunk » Mon Aug 06, 2018 9:26 pm

Thanks Chris...….Yes I am familiar with your endeavors into MFA and HEGO functions. LOL, I think just about everything Ive read had your name in it somewhere.

I was able to get out for about an hour doing some gentle cruising to see what happens. I ended up reducing only the top 2 cells of FN346 by about a third, set all my bias to zero and adaptives off. The engine seemed to feel better/smoother. There was no sign of that slight jerk as lambse drives lean and hangs. Instead it now quickly swings the other way. Its too early to say but it appears to have also cured an occasional lean pop after sitting at a light and tiping in. Looking at my log it appears Lambse now also wants less fuel. I have always felt I run richer than Lambse was telling me down low based on the soot stain on my garage floor. LOL or maybe its the Pan-Evac doing it....I dunno. I will have to adjust my fueling and see if things remain stable. Funny you talking about fuel economy, one of the first things I noticed is what BE reported as my average MPG...… I dropped about 2 mpg compared to yesterday. Maybe coincidence?

John
1987 Turbocoupe.
A3M1/A9L, BE/EA, Tweecer RT.
306,Single Turbo, Ported E7's, Ported Stock Intake, 42lb Matched Green Tops, PMAS 3" Blow-Thru Protube (42# supercharger calibrated),T5z, 3.73 gears
..... Nothin Fancy.......Just something to keep me from the honey-do list.........

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