Questions understanding reading logs

Decipha's custom GUFX strategy covers all 89-93 foxbody ecu's including the 88 mass-air california ecus.
MX-Brad
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Vehicle Information: 1990 5.0 swapped Miata T5 7.5irs w/3.27

Questions understanding reading logs

Unread post by MX-Brad »

Decipha, I'm just posting this here so other people can relieve you of answering my stupid beginner questions. I know you're busy and I don't want to bogart your time until it's necessary, like when I need my tune updated.

I'm a Premium member, and Decipha has done a great job getting my tune close to where I want it.

Where should the ISCDTY sit while driving? I'm slowly getting the throttle stop so it sits at around .15 at warm stable idle but when driving it often sits at around .75. Maybe I'm not understanding the function of the ISC, but when driving, shouldn't the ISC essentially be off since the throttle body is controlling the air intake at that point. ie if driving around and using the pedal, why would the ISC need to contribute air?
I didn't see this mentioned in the write ups, so thought I'd ask here.

Also, I'm a little lost on the LAMBSE and KAMFR. KAMFR is long term fuel trims (which I don't really understand either) ? I notice in a log I took tonight that sometimes my KAMFR reads in the .700's and turns orange while driving in slow cruise. Is that showing a lean or rich condition? It coincides with a slight hesitation or buck at those slow speeds.

Grateful for any explanations.
Cheers. Brad
m-barans
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2001 Ford Lightning SVT F-150 stock setup w/ inlet ported M112, bassani SS exhaust system from the manifold flanges back. Work/Street truck. Next build…

Re: Questions understanding reading logs

Unread post by m-barans »

The ISC duty cycle is how much the ECU is commanding the Idle air control (throttle body bypass) valve. At “idle” speed it should be lower. When driving around it will be commanded higher to keep the engine from stalling when the throttle plate slams shut on deceleration and help transition back to idle “dash pot”. Lambse is the value the ECU is targeting for an air fuel ratio. If your calibration is right then your lambda (measured air fuel ratio) will match the lambse. The ecu learns the fueling errors in closed loop operation (monitoring feedback from factory 02 sensors) and applies that correction (KAMRF). Hope this helps
MX-Brad
Posts: 54
Joined: 2021 Feb 16, 00:20
Location: Exeter Ontario Canada
Vehicle Information: 1990 5.0 swapped Miata T5 7.5irs w/3.27

Re: Questions understanding reading logs

Unread post by MX-Brad »

Thanks.....yeah that makes sense about the ISC.....it’s a main component of dashpot control.

Still a little foggy on the fuelling. The Lambse is what the ecu is commanding. Based on what? Is that a number calculated by the tuner and input into a fuel table or maf count table? Must be based on the adcounts requested during initial tuning, right?
Kamfr is what’s really happening with fuel, based on info from the hego?
From what I’m reading, lambse and kamfr should be pretty close to 1.00 if fuel is right. If kamfr is reading in the .700 range does that indicate simply that fuelling is rich, or that it is adding fuel? And what would be the cause of the kamfr reading in that range?
See....still pretty foggy, but picking away at it.
Thanks.
Blocmi
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Re: Questions understanding reading logs

Unread post by Blocmi »

The targeted Lambse is either 1.00 in closed loop, or from a table in open loop.

The actual Lambse in closed loop will be what is required to make the O2 sensors switch between rich and lean, AKA short term fuel trim.

KAMRF is your long term fuel trim error, expressed as a multiplier.
It looks at your closed loop Lambse over time and says hey, lately, at a MAFV of 2.5v the Lambse isn't switching at 1.00, it's switching at 0.90, it's off by 10% lets correct that...

IIRC a KAMRF value below 1.00 means fuel is being removed.
MX-Brad
Posts: 54
Joined: 2021 Feb 16, 00:20
Location: Exeter Ontario Canada
Vehicle Information: 1990 5.0 swapped Miata T5 7.5irs w/3.27

Re: Questions understanding reading logs

Unread post by MX-Brad »

Thanks for the explanation.
MX-Brad
Posts: 54
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Vehicle Information: 1990 5.0 swapped Miata T5 7.5irs w/3.27

Re: Questions understanding reading logs

Unread post by MX-Brad »

Ok, next round of questions. From the Dashpot writeup:
SURGING IDLE - PRACTICAL EXAMPLE

Lets say your idle is screwed and you just can't seem to get it tame enough for the ECU to control the ISC correctly. You may have to temporarily crack open the throttle blade to get the idle tame and do the following:

Get her up to warm idle (180-200*F ECT), once shes been idling at normal operating temp for 5 minutes take note of the ACTUAL
RPM
MAF
ISCDC
IPSIBR
ISCKAM2
let the idle settle and watch ipsibr and isckam2 they should both be working their way towards 0.000

add them both together, if their sum is +/- 0.05 then call it good and never look back

otherwise if their sum (ipsibr+isckam2) is greater than 0.05, then you need to open the throttle stop a little bit (1/4 turn)

If their sum is less than -0.05 then you need to close the throttle body stop a little bit (1/4 turn)
Has IPSIBR and ISCKAM2 been given different names? I don’t have them on my dashboard and don’t see them listed in the “Edit Gauges”.

Just trying to understand a few easy things first.


Also, going back to fuelling, here are a couple of screen shots. One shows KAMRF in the .700's. So, if I understand this right, I'm in closed loop, so HEGO's are monitoring the AFR in the exhaust pipe, the ECU is asking for a LAMBSE of whatever is entered in the MAF table(yes?) and the KAMRF’s are making the correction to reach the targeted LAMBSE. Is that right?
What is making the KAMRF think it needs that much fuel removed when LAMBSE is currently showing close to 1.0. That's where you want LAMBSE and KAMRF to stick around.....is that correct?

In the other screenshot it shows LAMBSE at around 1.200 with KAMRF providing virtually no correction. What is going on there that makes KAMRF not add fuel to fix it?
Incidentally, both instances happen at about 300 IMAF.
Just not sure if I'm seeing something off, or if all is good.
Attachments
low kamfr.png
high lambse.png
m-barans
Posts: 48
Joined: 2021 Feb 16, 23:09
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Vehicle Information: 2003 Mercury Marauder 300A with new stock bore IRON 4.6 block, Manley crank, Manley H-tuff h-beam rods, CP pistons with stainless rings, GT500 lash adjusters and rollers, D series cylinder heads, VMP GEN3R 2.65 L TVS blower, 80 lb/hr FRPP Siemens Deka injectors, HPX slot 100mm MAF, coyote mustang fuel pump with PPRV, Moates quarter horse and TunerPro RT with support from Decipha, RZASA strategy.

2001 Ford Lightning SVT F-150 stock setup w/ inlet ported M112, bassani SS exhaust system from the manifold flanges back. Work/Street truck. Next build…

Re: Questions understanding reading logs

Unread post by m-barans »

You lack some conceptual understanding of the basic open/close loop operations and how the maf based ecu works.

The factory O2s are narrow band sensors. This means that they are basically designed/calibrated to measure a lambda value of 1 (stoic). The can’t measure much more or less than stoicism (hence narrowband)
This means they are only used in “closed loop” fueling mode when the ECU is commanding a lambse of 1.
The ECU varies fueling slightly to get the 02 signals to switch (lean/rich) right around stoic.

The trimming of fuel required to get those narrowband O2s to “switch” is learned and that’s basically what the KAMRF represents.

The MAF is the primary sensor input to the ECU to help it calculate fuel needed. (Mass of air measured + mass of fuel needed = desired air fuel ratio)

There is a base fuel table, it is populated with lambse values . Lambse value of 1 only used in closed loop operation because that’s all the narrowbands O2s can report.

Lambse is a derivative of the air fuel ratio. There is an AFR scalar that has a stoic value for the fuel your running.

The ecu commands lambse of 1. By measuring maf counts and referencing the maf transfer function it now believes X mass of air is entering engine, it then references the fuel injector model and calculates how much injector pulse is needed to deliver Y mass of fuel to achieve stoic. Or lambda of 1

Again, It varies fueling to get that narrowband to report and adapts or trims fuel for corrections.

So now we know that if our base fuel table has lambda values less than 1 like .8 for example, then the ecu is in open loop or ignoring the narrowband O2 sensors because they are useless for measuring anything other than stoich. This is why a wideband is needed so that we can measure outside of that “band” near stoich if our ecu is commanding lambse less than 1.

We also know that O2s only measure or react to oxygen. They are useless and do not measure fuel. Incomplete combustion and/or air leaks into the intake or exhaust all will negate the ability of the narrowband O2 sensor to provide useful data to the ecu and you as the tuner.

If we are tuning we are operating on the assumption that the setup is mechanically sound first and then adjust maf transfer and or injector model to “calibrate” the operation. If there is an underlying issue, the calibration will be incorrect. You can’t reverse engine something that doesn’t work right to being with and expect good results. This is basically what we are doing with the data we know is correct and working backwards to solve for example, a larger maf sensor.

Hope this helps
m-barans
Posts: 48
Joined: 2021 Feb 16, 23:09
Location: Oregon
Vehicle Information: 2003 Mercury Marauder 300A with new stock bore IRON 4.6 block, Manley crank, Manley H-tuff h-beam rods, CP pistons with stainless rings, GT500 lash adjusters and rollers, D series cylinder heads, VMP GEN3R 2.65 L TVS blower, 80 lb/hr FRPP Siemens Deka injectors, HPX slot 100mm MAF, coyote mustang fuel pump with PPRV, Moates quarter horse and TunerPro RT with support from Decipha, RZASA strategy.

2001 Ford Lightning SVT F-150 stock setup w/ inlet ported M112, bassani SS exhaust system from the manifold flanges back. Work/Street truck. Next build…

Re: Questions understanding reading logs

Unread post by m-barans »

I just wanted to add that I lack understanding as to why the ecu would command a lambse greater than a value of 1. My best guess is that in this case it expecting fuel vapors from the tank are being introduced to the intake manifold via the vapor management valve. Maybe someone who knows could address this concept of lambse great than 1 being commanded by the ecu?
m-barans
Posts: 48
Joined: 2021 Feb 16, 23:09
Location: Oregon
Vehicle Information: 2003 Mercury Marauder 300A with new stock bore IRON 4.6 block, Manley crank, Manley H-tuff h-beam rods, CP pistons with stainless rings, GT500 lash adjusters and rollers, D series cylinder heads, VMP GEN3R 2.65 L TVS blower, 80 lb/hr FRPP Siemens Deka injectors, HPX slot 100mm MAF, coyote mustang fuel pump with PPRV, Moates quarter horse and TunerPro RT with support from Decipha, RZASA strategy.

2001 Ford Lightning SVT F-150 stock setup w/ inlet ported M112, bassani SS exhaust system from the manifold flanges back. Work/Street truck. Next build…

Re: Questions understanding reading logs

Unread post by m-barans »

My second best guess for a Lambse greater than a value if one means the ECU has calculated that the engine is in an excessively rich condition and trying to compensate. Again, maybe someone more knowledgeable can chime in on this topic.
PaulC-turbo5.0
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Re: Questions understanding reading logs

Unread post by PaulC-turbo5.0 »

ispibr and isckam have been combined by decipha recently and they are now logged as desmaf and in the same spot on the dash.

in the second screen shot the throttle is closed so you are in decel and why the lambse is at 1.2, I wouldnt pay much attention to that. The ecu will command whatever lambse is needed to get the hegos to switch. once dialed in they will bounce back and forth around 1 so seeing them above 1 is normal.

m-barans has given you good explanations and also keep reading the write-ups until things start to click, I know it took a long time for me to get a handle on things.

knowing more about your setup would help giving suggestions on what you should do. also i see your a premium member so wont Decipha be tuning this for you and showing how?

If you have known injectors and all their data is in the tune correctly then you need to dial in the maf transfer. to do this you need to be steady on the throttle and hold each imaf point for at least 10 seconds to allow it to stabilize. I assume you have a Decipha base tune so you should easily be able to use the histogram which will make this much easier, its the first one on the list and set it to running average. I would suggest resetting your KAMs and turn the KAM update off at this point until you get it dialed in. Find a nice stretch of road that you can run and try to hit every point on your MAF curve from idle to as high as you can comfortably go letting each one stabilize for at least 10 seconds. multiply the MAF transfer by whatever number is in the histogram once you have a good amount of samples at each point. In the end you should be able to get your KAMs to stay between 1-1.03 while lambse bounces back and forth around 1. You always want to be adding fuel so keep the KAMs above 1.

You can also use the KAMs to dial in the curve if they are mature but this will take a while so its easier to use the historgram. Use the KAMs to fine tune the curve to perfection after the initial dial in. To use the KAMs, in your example above with lambse's around 1 and KAMs at .7 you need to go to the 300 imaf count on the MAF transfer and multiply that by .7.

if you dont have known injectors with published data dialing in fuel can be a bit different and would require advice from someone with more experience. it is also discussed in detail in the write-ups. good luck and keep at it you'll start to understand it more and more.
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