Flat floor shifting causes FLKC?

[Tor]

It looks to me the FFS function (set at 6000 rpm) causes the AFR to go up when the rpm limiter kicks in and cuts the fuel. Maybe this temporary lean mixture is causing knock?



Same log/drive with a pull trough 3rd and 4th with normal shifting:



Link to log:
http://datazap.me/u/tor/stg1-102-v12...lo=17-19-31-41

[steve99]

I never used it much on oft, but i suspect thats why the ecutek version of ffs sets afr to 9.5 and retards timing by 20 degrees during the flat foot shift.

The opensource one as you found just uses the standard fuel cut rpm limiter

[Tor]

Thanks for the description. The Ecutek implementation must be there for a good reason. That's a huge timing reduction.

So if there might be massive actual knock going on during the shifts, I think I will disable FFS again.

[steve99]

Originally Posted by Tor

Thanks for the description. The Ecutek implementation must be there for a good reason. That's a huge timing reduction.

So if there might be massive actual knock going on during the shifts, I think I will disable FFS again.

you might be able to fix it using the "Transient Ignition retard table" as that's exactly what its for knock reduction on transients like shifting


http://www.ft86club.com/forums/showthread.php?t=50088


Maybe add some transient retard at the high load high rpm area, bottom right of table, try entending the -9 area al the way to end above 5600rpm, that should sort it. but if your only seeing about -2 max knock -5 or even -3 so should be more than enough


but it might make throttle a bit laggy, will be suck it and see

[steve99]

Hmm wait, that's not going to fix it as throttle is staying wide open during a flat foot shift air flow is hardly changing hence engine load is almost constant during shift. As load is just a calculated value of maf air flow. So the transient retard table has nothing to trigger off I suspect. Unlike a conventional shift where you lift off throttle and load (air flow) will drop, hence the reason ecutek system triggers its own ignition retard (and keeps afr from going lean) during an ecutek FFS I suspect.


I think you going to need a rom software code change to sort it out

[Tor]

Originally Posted by steve99

I think you going to need a rom software code change to sort it out

Maybe worth drawing the attention of Shiv to this? I suppose an Ecutek similar implementation is probably not going to happen due to the amout of work required.

My worry is not the -1.3 FLKC , but would we know for sure what going on behind the scenes if the ECU is not designed to handle this particular scenario? Could there potentially be a lot more knock that the ECU doesn't really know how to compensate for?

[D_Thissen]

Interesting... I wonder if the same issue occurs when you use 'launch control' ?

[renfield90]

Originally Posted by D_Thissen

Interesting... I wonder if the same issue occurs when you use 'launch control' ?

If I'm not mistaken this motor knocks more at higher RPMs, so you might actually be ok there. But that raises a very good point.

[Nah]

A quick look at you're FLKC, if it's 0 than no ign retard = no knock... if your fuel trims are off you'll probably see some knock, also, if your just slamming off the rev limiter don't be surprised to see knock either. I like to "float off the limiter." Easier on the gaskets

FFS probably needs re write in code like steve99 said. From my experience and I'm sure many others can agree, it's pretty bad.

[churchx]

Hmm, is FFS really something of must have to be efforts spent on fixing it worth it? I always thought of it as cool to try/play once or twice and then never actually use it in DD or in trackdays later on.

[steve99]

Originally Posted by Tor

Thanks for the description. The Ecutek implementation must be there for a good reason. That's a huge timing reduction.

So if there might be massive actual knock going on during the shifts, I think I will disable FFS again.

Their is a table (defined in ecutek anyway) is not a racrom table so will be in standard ecu software that retards timing when clutch depressed. Not sure if its defined for your calid in romraider. You could likely use that table to pull a bit more timing during FFS and cure the knock.

[Tor]

Interesting, will trawl throught the tables and see if I can find anything. Thanks.

[aagun]

try that table called like timing above speed in gear