Lean spike between shifts

[stigc8]

Hi,

Mapping my mates car essentially the same mods as mine. After reviewing the logs, ive noticed theres a lean spike between shifts when slamming gears. Below is 1-2 example, but all gears do it. can see it hits 17afr once 100% TP is back, 11.6psi boost at that moment. 

Car shifts fine without hesitation, wideband sensor is brand new.

Ive played with accel enrichment, minor changes do nothing for the spike, with major changes managed to get it to show 13.5 14afr at same point but now it bogs between shifts can feel it doesn't like it, guessing its better to just ignore it and go by how it feels?

Also tried changing cells on the fuel map it runs over before and at that stage by upwards of 25% with little to no change.

attached pic of log if anyone has any input ? thankyou

 

[DerekAE86]

Picture of the log isn't really enough. Need the tune file and the log file.
It's possible the tune has an aggressive lift off fuel cut?

[koracing]

I would tune more for feel than lambda reading unless it's causing knock or something else detrimental.  There will be a happy state that feels the best and usually that means it's running the best in that state.

[stigc8]

22 hours ago, DerekAE86 said:

Picture of the log isn't really enough. Need the tune file and the log file.
It's possible the tune has an aggressive lift off fuel cut?

hey mate, thanks for your thoughts, overrun fuel cut is off though.

5 hours ago, koracing said:

I would tune more for feel than lambda reading unless it's causing knock or something else detrimental.  There will be a happy state that feels the best and usually that means it's running the best in that state.

Thanks for your reply, I think in this case it may be the way to go. The lean spike is really only for 200ms. I know lean spikes like this can be normal with flat foot shift due to ign cut, but not sure if these are normal so to speak without it.

Default accel clamp settings shift best, as mentioned above, ive managed to get it to read richer but can 100% feel a rich bog between all gears which makes it shift like crap.

[stigc8]

Just an update to follow this up for future searches, with lots of testing and trying different things, default settings are best.

The car goes full rich, then immediately full lean when you back off the throttle under boost looking at gauge itself.

What is actually happening on the log between shifts, the wideband is picking it up with a slight latency delay making it look like its lean back on throttle, but in reality, its actually happening earlier, its also evident with the rich dip on the log after tp back off.

[k4nnon]

6 hours ago, stigc8 said:

Just an update to follow this up for future searches, with lots of testing and trying different things, default settings are best.

The car goes full rich, then immediately full lean when you back off the throttle under boost looking at gauge itself.

What is actually happening on the log between shifts, the wideband is picking it up with a slight latency delay making it look like its lean back on throttle, but in reality, its actually happening earlier, its also evident with the rich dip on the log after tp back off.

Hey just to add some info to this,, If you are using any type of aggressive Ignition cut/gear shift control between shifts then it will read lean at those moments. Not that the engine is actually lean. The fuel is there but is unburnt by the lack of ignition. The o2 sensor reads the oxygen and not the fuel. So too little fuel will read lean, and also unburnt fuel will read lean. Go by how the car feels and watch the logs. If fueling is good though the pull and back to good right after shift then its probably nothing to worry about.