A/F Ratio Oscillation

[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 exhaust /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!

[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.

[K20Elite]

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.

[Hondata]

Unlikely to be the o2 sensor. Do you have the fuel pump limit enabled?

[K20Elite]

Unlikely to be the o2 sensor. Do you have the fuel pump limit enabled?

Fuel pump limit is not enabled

[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

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 exhaust, Greddy frontpipe and catback

[Hondata]

From your datalogs you are not experiencing the same problem as the OP.

[Kenneth12]

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????

[Hondata]

The AF looks normal to me.

[Kenneth12]

The AF looks normal to me.

AF2.PNG

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?

[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

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

It looks like you're getting wheel slip around the time these oscillations occur.

[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]

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

(AFM Graph)

433A5941-E273-419E-89D3-11C9B540786A.jpeg

I have smoothed it out but haven’t gotten a chance to test it yet.

[ttking885]

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 exhaust, 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]

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

or should I adjust air charge value???

your air charge values are falling into a leaner cell on the minimum lambda tables.. thats why yours is jumping around.