2116 replies to this topic

[CHILL Gone DUTCH]

so all the setting in the transient has a effect on the other setting in the transient 

 

heres the table again as its in the other thread 

 

[CHILL Gone DUTCH]

hope this helps smiley but its not a easy thing to explain 

but it al need balancing with each other 

[smiley]

Thanks chill

[Exmantaa]

Transient mapping is not easy. It's often called x-tau mapping, so google that. Megasquirt forum explains it a bit, but has to do with the mass latency of the air and fuel, and also with the fuel wetting of the port walls (so that amount does not reach the combustion chamber > lean) and later in time the evaporation of that same fuel (extra fuel amount > rich).

 

In steady state this will reach an equilibrium, same amount deposits on walls as is evaporating, but in the transient loads you will get lean and rich spikes due to these effects. 

(I'm still searching for a good way to measure/log/map this..)

 

ps; during fuel learning sessions; you therefore should be very gently with the pedal movements, as these transient effects can/will mess up the logged AFR's

Edited by Exmantaa, 10 February 2016 - 03:07 PM.

[siztenboots]

aka Tip-in

 

on carbs you would have a dashpot on the needle and a float chamber

 

on the newer management it is much more about meeting emissions , calculating Tau is the easy bit

[siztenboots]

are you , ie. groups seeing this problem using stock throttle body , or bigger?

 

how much map change is there when it occurs , and over what duration

[Exmantaa]

are you , ie. groups seeing this problem using stock throttle body , or bigger?

 

how much map change is there when it occurs , and over what duration

 

Ehhh... it's a dark area where people just experience not optimal/bad on-off throttle behavior and/or stalling engine from coasting down, often on a "stage x" engine on cams and some after fitting the bigger LS4 throttlebody.

But this could also be due to numerous other issues in the mapping... (the correct injector latency settings to name one.)

 

Or mechanical issues; a small vacuum leak in the intake tract can mess up your idle/low load very badly.

[oakmere]

Any advice on improving the mapping on initial pulling away. As I first pull away the car can want to stall. The cams and lightweight clutch don't help but I think the mapping can be improved. I can release the clutch with no throttle and it dosn't stall. It is only when throttle is introduced the problem occurs. The biggest improvment was made by flattening the idle ignition and making sure the main map ignition was higher than idle. Would any of the transient settings help?

[Exmantaa]

Could be, but you need a (quick..) wideband to see if it maybe is momentarely too lean or too rich.

Or just trial and error with the transient settins...

 

Not sure if you can log the event and then see in OBD at what exact transient point you are in the map??

[oakmere]

Yes I need to spend some time working on this as I have never got it quie right. I think a wide band would be a good investment despite being a lowly N/A.

[siztenboots]

with my latest map I can quite happily pull away in second gear, just the clutch and no throttle , lots of ignition timing kept in reserve

 

there is no reason why the same cannot be achieved on 2,2 by cleaning up a lot of the self learnt adaption tables and smooth out the anomalies manually

 

 

[slindborg]

x-tau was the most complicated (yet simple) thing I ever learnt When the lead calibration engineer was explaining it to me it was rather hard to comprehend, and that maths/AF sensor readings are near pointless for it, its all done by feel and to some extreme ways with an oscililloscope on the injectors.

 

Idle drive (what Steve alludes to) is also hard but lovely to get right.

Bags of advance to spare are key, maybe some PID calibration too (do you have addess to any PID elements in the dutch stuff or has that been hidden?

[Exmantaa]

with my latest map I can quite happily pull away in second gear, just the clutch and no throttle , lots of ignition timing kept in reserve

 

there is no reason why the same cannot be achieved on 2,2 by cleaning up a lot of the self learnt adaption tables and smooth out the anomalies manually

 

 

 

 is easy....

But now slam the trottle open and it should pull straight away to max rpm with no hick-ups or bogging down... And the same then for low, mid and high rpm/load situations. (the upper ones are no issue, as the relative MAP/throttle change is less and there is already a significant loading of the engine.) 

[TFD]

For reference: The original Z22SE maps

 

Idle

 

 

Target AFR

 

 

Transient

 

 

 

Edited by TFD, 13 February 2016 - 12:50 PM.

[siztenboots]

maybe everyone should just get one of these http://www.ebay.co.u...fEAAOSw3ydVs9bR

[slindborg]

maybe everyone should just get one of these http://www.ebay.co.u...fEAAOSw3ydVs9bR

 

What kind of thunderpants falls for that?

[TFD]

So I made a new transientmap out of Chill's and Smiley's map and all seems well now when revving in neutral. Car doesnt stall/hikup anymore.  Think this is due to more fuel in the enrichment area. Still have to roadtest it to make sure but the weather is sjeit at the moment.

 

Another issue: I can only adjust the values in the maps by using the EDIT menu. If I adjust the values manually, OBD doesn't make the values permanent in the ECU. Normal or something is off?

[oakmere]

No that is normal

[TFD]

 

 

...or actually   , too much hussle.

[oakmere]

I know Not sure why it is like this?