A/F Ratio Oscillation

FK2 Civic Type R 2015-2017 and FK8 Civic Type R 2017-2018
K20Elite
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Joined: Fri Jun 26, 2020 5:49 pm

A/F Ratio Oscillation

Post by K20Elite »

Hello,

I was in the process of having my car E-Tuned and have run into A/F ratio Oscillation issues. I will attach a graph and can provide datalogs as well.
My mods are PLR Intercooler / PRL Inlet pipe / PRL Charge pipes / PRL HVI / RV6 Catted downpipe /RV6 Frontpipe / J's Exhaust

I thought there may be a leak in the inter cooler and changed out to a new one - oscillation is still there.

Please help if you have possible solutions.

Thank you!
Attachments
Test pull 3 6-16.fpdl
(98.2 KiB) Downloaded 104 times
Ricky_AFROscillation.png
Ricky_AFROscillation.png (39.19 KiB) Viewed 6316 times
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Hondata
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Re: A/F Ratio Oscillation

Post by Hondata »

Unstable air flow over the AFM, fuel pump limiter enabled, bad o2 sensor. Also a 2nd gear run is not going to be consistent because of TC/VSA.
Hondata
K20Elite
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Re: A/F Ratio Oscillation

Post by K20Elite »

Hondata wrote: Sat Jun 27, 2020 1:02 pm Unstable air flow over the AFM, fuel pump limiter enabled, bad o2 sensor. Also a 2nd gear run is not going to be consistent because of TC/VSA.
Thanks for the response, what could cause unstable airflow over the AFM? I will look into the O2 sensor, this happened kinda randomly so assuming maybe the O2 sensor was damaged some how.
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Hondata
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Re: A/F Ratio Oscillation

Post by Hondata »

Unlikely to be the o2 sensor. Do you have the fuel pump limit enabled?
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K20Elite
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Re: A/F Ratio Oscillation

Post by K20Elite »

Hondata wrote: Sun Jun 28, 2020 2:49 pm Unlikely to be the o2 sensor. Do you have the fuel pump limit enabled?
Fuel pump limit is not enabled
Kenneth12
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Re: A/F Ratio Oscillation

Post by Kenneth12 »

Hello
Im having same situation with my AF, there is some strange oscillation and I have made the following checks based on your post
AF.PNG
AF.PNG (181.4 KiB) Viewed 5732 times
Corrected AFM
STFT.PNG
STFT.PNG (92.96 KiB) Viewed 5732 times
LTFT.PNG
LTFT.PNG (31.57 KiB) Viewed 5732 times
Fuel pump limiter is not enabled
O2 sensor, I have no reason to believe it has gone bad

No traction control is enabled during oscillation time

Honestly I cannot understand why this is happening or how to correct it
I have made a lot of logs in different conditions (cold IAT2, hot IAT2, even tried different fuel brand) and it happens all the time

Could you help me?
I am worried this could damage my engine

Mods: Stock Intake, Stock Intercooler, PRL Downpipe, Greddy frontpipe and catback
Attachments
LongLOG.fpdl
(2.86 MiB) Downloaded 86 times
91Custom.fpcal
(19.41 KiB) Downloaded 83 times
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Hondata
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Re: A/F Ratio Oscillation

Post by Hondata »

From your datalogs you are not experiencing the same problem as the OP.
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Kenneth12
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Re: A/F Ratio Oscillation

Post by Kenneth12 »

Hondata wrote: Sun Sep 06, 2020 8:19 pm From your datalogs you are not experiencing the same problem as the OP.
Could you please help me to find the reason of why my AF is not stable????
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Re: A/F Ratio Oscillation

Post by Hondata »

The AF looks normal to me.
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Kenneth12
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Re: A/F Ratio Oscillation

Post by Kenneth12 »

Hondata wrote: Mon Sep 07, 2020 8:11 am The AF looks normal to me.
AF2.PNG
AF2.PNG (188.48 KiB) Viewed 5687 times
This is another example ... im worried about this behaviour

Even air charge is making oscillation
I have seen many other logs and I cannot find this type of behaviour

Am I making a mistake with my calibration?
how can I improve this behaviour?
Attachments
LongLOG_2.fpdl
(1.88 MiB) Downloaded 79 times
Centripetal
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Re: A/F Ratio Oscillation

Post by Centripetal »

Perhaps, I can help by bringing you through the process I used to look at your log. At around 10:00 in the datalog I noticed something interesting. I've marked the points of interest 1, 2, 3.
1 - Decrease in AFM ~2% while throttle plate is 99% open
2 - Increase of AFM ~2.5% while throttle plate is 99% open
3 - ECM is reacting to something because throttle pedal is 100% and throttle plate jumps down to 55%
datapoint1.png
datapoint1.png (40.53 KiB) Viewed 5665 times
Then I toggled through the templates until I saw something that could be a possible cause. It looks like traction control was kicking in.
possible_root_cause.png
possible_root_cause.png (38.06 KiB) Viewed 5665 times
It looks like you're getting wheel slip around the time these oscillations occur.
jpierro79
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Re: A/F Ratio Oscillation

Post by jpierro79 »

This a know problem at around 4.7 volts fuel oscillates uncontrollably. It’s in the MAF scaling. I’ve already fixed a lot of cars using a MAF scaling I built just for this.
The problem is a couple of the values translate to positive them negative trim correction which makes the afr oscillate cause the ecu is trying to see what fuel will fix it. You can NOT just add to MAF scaling I had to literally break down the incremental increase to find the errors in it. It takes many hours.
Cars on meth or port do not have this issue because trims stay negative.
sloth4urluv
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Re: A/F Ratio Oscillation

Post by sloth4urluv »

jpierro79 wrote: Wed Feb 03, 2021 2:15 am This a know problem at around 4.7 volts fuel oscillates uncontrollably. It’s in the MAF scaling. I’ve already fixed a lot of cars using a MAF scaling I built just for this.
The problem is a couple of the values translate to positive them negative trim correction which makes the afr oscillate cause the ecu is trying to see what fuel will fix it. You can NOT just add to MAF scaling I had to literally break down the incremental increase to find the errors in it. It takes many hours.
Cars on meth or port do not have this issue because trims stay negative.
Do you mind sharing the AFM table?
I am interested to see what kind of changes you made.

One thing I’ve noticed but am not sure if it is related yet, but around the voltage that I oscillate at there is a step change in the first derivative of the AFM table.
(Derivative)
CA9E08F6-1659-438C-9E9D-07712AECAA2F.jpeg
CA9E08F6-1659-438C-9E9D-07712AECAA2F.jpeg (209.04 KiB) Viewed 621 times
(AFM Graph)
433A5941-E273-419E-89D3-11C9B540786A.jpeg
433A5941-E273-419E-89D3-11C9B540786A.jpeg (362.5 KiB) Viewed 621 times
I have smoothed it out but haven’t gotten a chance to test it yet.
ttking885
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Re: A/F Ratio Oscillation

Post by ttking885 »

Kenneth12 wrote: Sun Sep 06, 2020 8:04 pm Hello
Im having same situation with my AF, there is some strange oscillation and I have made the following checks based on your post

AF.PNG

Corrected AFM
STFT.PNG
LTFT.PNG

Fuel pump limiter is not enabled
O2 sensor, I have no reason to believe it has gone bad

No traction control is enabled during oscillation time

Honestly I cannot understand why this is happening or how to correct it
I have made a lot of logs in different conditions (cold IAT2, hot IAT2, even tried different fuel brand) and it happens all the time

Could you help me?
I am worried this could damage my engine

Mods: Stock Intake, Stock Intercooler, PRL Downpipe, Greddy frontpipe and catback

your air charge values are falling into a leaner cell on the minimum lambda tables.. thats why yours is jumping around.
Kenneth12
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Joined: Sun Sep 06, 2020 7:42 pm

Re: A/F Ratio Oscillation

Post by Kenneth12 »

this means I should close the value gap between the cells in the minimum lambda tables??????

or should I adjust air charge value???

ttking885 wrote: Sun Jun 20, 2021 2:31 pm
your air charge values are falling into a leaner cell on the minimum lambda tables.. thats why yours is jumping around.
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