Fast idle good by REALLY lean - NOT VVE

[Behold]

Helping someone tune there VE GTS with an E38

When revved to about 2k in neutral the AFR goes to about 16-17 sometimes higher. But in gear under load in the same area on the VVE it's super rich. As we lean it out the fast idle gets leaner. This is almost like there is some correction table.

What might it be? It's stumping me.

Thanks.

[joecar]

Post log/tune files.

[Behold]

As requested.

The VVE is more updated now but understanding why its so lean only not under load would be great.

Thanks

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[joecar]

Helping someone tune there VE GTS with an E38

When revved to about 2k in neutral the AFR goes to about 16-17 sometimes higher. But in gear under load in the same area on the VVE it's super rich. As we lean it out the fast idle gets leaner. This is almost like there is some correction table.

What might it be? It's stumping me.

Thanks.
Are you running VE-only or VE/MAF...?

[Behold]

VE only. SD Closed loop longer term but tune is in SD OL mode for VVE tuning.

[Behold]

Joe did you notice anything?

I assume an idle correction is causing some leaning out. but surely fast idle would be outside the idle table?

[joecar]

VE only. SD Closed loop longer term but tune is in SD OL mode for VVE tuning.Are you seeing an immediate MAF DTC...?

[joecar]

Try setting B8003 to all zeros.

[statesman]

Reset the fuel trims.

[Behold]

Done. No real difference.

[Behold]

Reset the fuel trims.

Trims are off in the tune. The ltft does seem to have figures in them. But surely they are not doing anything?

[Tre-Cool]

the e38/67 controllers are a strange beast. they will do weird fueling after a flash. generally after a restart i find fuel mixtures on light load/idle will be a bit silly and then come into line shortly after a small drive or high map scenario.

[Behold]

So how do you tune the VVE? For idle or driving? Then let the fuel trims sort it?

I get you will never have a perfect VVE due to the way it works and has to be linear in a zone removing curves in some areas.

The issue is the VVE is so far off in both directions that you sort one the other is massively screwed. It's still feeling like an adder table.

[Tre-Cool]

Sorry, what i meant was you need to give the ecu some time after doing a flash for it to stabilize.

for example i often find that i can have spot on fuel trim for idle/cruise etc. but once i do a flash. restart. the idle will either be pig rich or lean. it varies from ecu to ecu.

It's partly to do with the IVT calculations & some other hidden background crap that goes on with them. It's especially more common on SD only tunes.

So dont go making changes to idle vve, log stationary idle. reflash and expect much to change or you'll end up chasing your tail.

Another thing to change for sure is how you setup the fuel g/sec table under the fueling tab. you have the same airflow fuel "multiplier" for 0-160kph. working with that can do wonders.