Tables with no effect??

Developer topics relating to software that provides a tuning UI to alter ECU code and data

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Tables with no effect??

Postby m3n0ch3 » Wed Sep 06, 2006 8:22 am

Hi guys,

I just noticed someting a little weird... it seems the Load vs RPM lambda bias table is either not taken under consideration from the ecu or doesn't work the way it' s intended.

I'm trying to accomplish a nice economy mode while still having lots of power by biasing the AFR in some load/RPM mode to get economy on the highway.... but what ever I put for bias above zero doesn't seem to be modifying AFR.. only number below zero seem to affect it.

Anyone else noticed this?
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Postby swifty » Fri Sep 08, 2006 1:51 am

I haven't changed that table, but I have changed the closed loop cruise afr and this does make a difference to the afr on cruise.

If you change this though be careful because I believe it has an impact on afr corrections and fuel learning that has a knock on effect in open loop. ie if you lean this out a bit then open loop fuelling may also be leaned out.
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Postby m3n0ch3 » Fri Sep 08, 2006 9:17 am

hmmmm unless I am wrong, in open loop, the ecu is not trying to reach cruise AFR but runs richer...

I set it to 15.3 and my open loop runs are still showing a nice lambda of 0.76 untill 6800 which is my boost decresing limit for now
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Postby xswrex » Fri Sep 08, 2006 10:11 pm

swifty wrote:I haven't changed that table, but I have changed the closed loop cruise afr and this does make a difference to the afr on cruise.

If you change this though be careful because I believe it has an impact on afr corrections and fuel learning that has a knock on effect in open loop. ie if you lean this out a bit then open loop fuelling may also be leaned out.


The bias tables are referenced in the disassembly, i haven't tracked it down yet to see when they are used.
The closed loop cruise AFR works fine. I have verified it in my ROM (A4SE900D). The resulting RAM value is a word @ 209DE
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Postby swifty » Mon Sep 11, 2006 3:03 am

Did you set the Cruise aFR to 15.3 before or after setting the open loop afrs ?
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Postby ride5000 » Thu Sep 14, 2006 6:08 am

i set my closed loop afrs before i attacked the open loop table.

however, since a different closed loop afr does not change the fuel trims i do not see how it should have an effect on the open loop afrs.

fwiw my target closed loop is 15.5:1, and my target higest load afr is 11:1
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