No changes to AFR

s300 and SManager software questions & answers
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ckendall
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Joined: Thu Feb 25, 2021 8:17 am

No changes to AFR

Post by ckendall »

I'm trying to get my new build running and I am running into an issue while trying to make changes to the low speed fuel table using the lambda overlay feature. I am using an AEM wideband wired to pin D10 (r136 & r138 are cut)/AF gauge matches S300, Bosch 1600cc injectors, Walboro 450, aeromotive FPR. I have the fuel pressure set at 35psi right now due to an original issue of the engine being way to rich at idle with the AFR around 10-11. I lowered the fuel pressure from 44psi to 35psi (which is where it is now) and played with the dead times to get it to idle around 14.5-15 for the first minute or so. As the engine warms up, the AFR's are all over the place. Using the Lamda overlay feature, when adding or removing fuel from cells by a percentage, their is no significant change in the AFR. At Idle, some areas will ask to take away 40%. Ill remove 20% in those cells, you can see the 3D table change, but this will not change the AFR. This just puts a huge dip in the table that has no effect to the AFR.

I've attached the datalog for this session. I think this may be an issue with the injectors, but I'm no expert. I'm just trying to get the AFR's correct at idle and partial throttle to get it to the dyno.
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Spunkster
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Re: No changes to AFR

Post by Spunkster »

The fuel pressure sounds low. I would get the fuel pressure up to where it should be, then make sure you have the dead times set correctly for the injectors you have. Changes should be made to the fuel tables themselves or the trims, not the fuel pressure.
ckendall
Posts: 3
Joined: Thu Feb 25, 2021 8:17 am

Re: No changes to AFR

Post by ckendall »

I will try adjusting the fuel pressure back to where it was. The only reason I initially lowered the fuel pressure was due to how rich the AF was as well as while making changes to the fuel table, the same issue was present. When adding or removing fuel to/from the table, the AF would not change and the lambda overlay would still read the same as it would prior to making changes to the fuel map. I only lowered the fuel pressure to see if this would cause the engine to run a bit leaner and to make sure something else wasn't causing this issue. The injectors did not come with dead times and I'm having a difficult time finding deadtimes from the manufacturer.

I've attached the calibration file if you would like to take a look.

Would incorrect dead times cause an issue with adjusting the fuel table? Would this cause the huge dip in the fuel table with no change in AFR?
ckendall
Posts: 3
Joined: Thu Feb 25, 2021 8:17 am

Re: No changes to AFR

Post by ckendall »

Here is the calibration file
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Spunkster
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Re: No changes to AFR

Post by Spunkster »

incorrect dead times on really large injectors will definitely cause a problem.
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