Load and AFR variations on data logs

VersaTuner for Mazda RX-8
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Bob_chala
Posts: 5
Joined: March 2nd, 2019, 5:23 am

Load and AFR variations on data logs

Post by Bob_chala »

Hi,
I'm french, I have a S1 drift :
RB street port
big intake,
full exhaust
air pump delete,
LS2 coils
only the first O2 sensor
ABS box delete
welded diff
electrical harness simplified
and many more things...

I'm not a ECU specialist. When I'm logging, I have big variations of load and AFR. Is it the same for everybody ?

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Bob_chala
Posts: 5
Joined: March 2nd, 2019, 5:23 am

Re: Load and AFR variations on data logs

Post by Bob_chala »

Image

AFR between 12.9 and 13.8 I cant have less variations

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Steve @ VersaTune
Lead tuner
Posts: 1143
Joined: March 29th, 2010, 12:58 pm

Re: Load and AFR variations on data logs

Post by Steve @ VersaTune »

RX-8s tend to have a lot of fluctuation in AFR.

The RX-8 has relatively low flow for such a large MAF tube. There are also spikes and dips when the SSV and APV open and close.
The S1 ECU uses a slow processor that can not sample the O2 sensor as fast as modern ECUs.

The result is AFRs that are not smooth. You can try to adjust the VE table or MAF table to correct. Make sure that you are correcting for steady state operation and not transient conditions.

Bob_chala
Posts: 5
Joined: March 2nd, 2019, 5:23 am

Re: Load and AFR variations on data logs

Post by Bob_chala »

Ok, thanks.
Nothing is good in this car ! :banghead :cry :biggrin2
Make a good tune is really a big job.

I also noticed that the table "Load calculation IAT ajustment" must be modified. AFR become lean when the weather is cold.

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