accel enrichment

[Denmark]

Hi All.


I seem to have a problem with accel enrichment , when the car is cold, as the car is bogging really bad, when i touch the pedal , when the car varms up it goes away,

So i would like to know a starting value in :

Acc cold multiplication factor (%) = 100

Cold accel added amount( -40c)(ms)=15.0


The numbers i have written is what i have now, but would like to know if You guys up the first value...


Thanks,
Skassa

[gunni]

I think your overfuelling it with 100% enrichment

try and take out until your good,
I have 0% in there and it might need more to be honest. But itÃ,´s only at idle where itÃ,´s bad normal driving is good while cold,
as you are running more fuel with warmup enrichment.

[Denmark]

Thanks,
So you think i need to lower the mutiplication factor, i just found this on wiki, were itÃ,´s apperently is jorgen recommended settings, were itÃ,´s at 120%, and 0 in the cold accel added amount.



http://www.vems.hu/wiki/index.php?page=MembersPage%2FJimW



I will give it a try, so ican check it tomorrow.


Thanks,
Skassa

[Denmark]

I did the recommended settings, and it drives like oe when cold, so this is great :)


Thanks,
Skassa

[Denmark]

Do You guys, also have a problem when the car is in neutral, and you want to rev it fast, itÃ,´s like there is a delay on the engine response,

That can be alot better with more fuel, but the when the car is being driven, itÃ,´s to much accel enrichment.

Do any of you have a sulution to that?

Thanks,
Skassa

[[email protected]]

tip-in fuelling off idle is a really weak point.  It would be awesome if we could scale enrichment by RPM and TPS change speed, I've asked for it, we even had something that we tested but I'm not sure what happened.  All we need is a 4x4 table...

[gunni]

Ok here is a theory of operations I have been thinking about.

Y axis - "dv/dt"
X axis - "rpm"

values in table are Gve values from the fuel table based on the KPA axis,
i.e when you move the throttle letÃ,´s say 20 dv/dt and at the current rpm there is a value in the cell of letÃ,´s say 80

What happens is that when you move the throttle that KPA valueÃ,´s calculated PW value is instantly selected ( assumed KPA ) for accelaration enrichment.

So using this there is a chance of using preemptive KPA value selection.

Ok.
Here is the accelaration enrichment table


Here we see that there has been a dv/dt of 18..
RpmÃ,´s are 2500
The value in the cell is 80.
The ecu uses that 80 as a KPA lookup from the VE table



Here we see that in the 80kpa and 2500rpm there is a VE value of 79.
the ecu would use this as assumed current MAP value while the actual map value is below (map delay)
itÃ,´s used until the actual MAP value reaches it or a set time perhaps.

[Sprocket]

Bear with me, i may be talking crap

I found that MAP changes almost at the same rate as as throttle. Question, why have a look up table when the MAP responds almost at the same rate? Would it not be better to have a table dv/dt x rpm and the bins used as an enrichment value biased to 100% (no enrichment) Then there only needs to be a time constant for acceleration enrichment duration.

As for deceleration enrichment, im not sure at all, if you could use the same table with a negative dv/dt, where the value enrichment becomes enleanment, IE instead of adding 10% its subtracts 10%, but uses the same table value??

[gunni]

map and tps change rates are different between engines.

In any case we need a table.
And stat. This throttle response is just making the using of vems horrible to be honest.

[[email protected]]

Okay I've written up a very simple method of acceleration enrichment.
http://www.vems.hu/wiki/index.php?page=GenBoard/UnderDevelopment/AccelerationEnrichment
Would people please go onto that page, click Edit and at the bottom before the line please put your UserName, that you too need this feature, as your engine shows the same enrichment issue.
It is then possible that we may be able to get a change made to improve the system - its not like we're trying to do something counter productive.

[Sprocket]

I had real problems with acceleration enrichment on the Mini 1400 SPi, and that would have to be the worst situation anyone could encounter, regards manifold design. I tried both MAP and throttle settings and they both reacted in the same manor. Data logs show that MAP is almost an exact trace of TPS where 'rate' is concerned. if MAP rate is the same as TPS rate, havin the TPS table look up the MAP in the VE table is pointless as it will be at that point anyway?? ???

I think there deffo needs to be a table, perhaps not a 16x14, but something that, as Rob said earlier, is RPM based. I would also like to see the enrichment biased to 100%, making it easier to understand how all these 'extra' bits work into the equasion. 100% being the VE value and unchanged (zero acceleration enrichment) 110% being VE value +10% (10% added of VE value) and 90% being -10% ( 10% subtracted of VE value) There still has to be a time constant as its this that differs from engine to engine.

It would be good if the table showed the bin thats active as in the spark, lamda and VE tables, that way you could tune it on the dyno quite easily, constant conditions and repeatable. It doesnt have to be perfect, a tollerence of rich would be acceptable.

Im just curious as to how OEMs do it. Taking for example the Rover Mini SPi, these left the factory either as 53bhp or 63bhp, after tuning the engine considerably 100bhp is achieveble with only a mild cam, this also includes increasing capacity from 1275cc to 1399cc, yet the standard ECU, as long as the injector size is increased, still manages to fuel the engine pretty close to how it left the factory. Its nearly a 100% increase in power yet the acceleration enrichments and warm up enrichments dont seam to give any issues. Perhaps they are VE biased, in that as the adaptive VE values change so does the warm up and acceleration enrichments.

Again, I may be talking crap.

We need something thats is not too complicated, but at the same time not too simple as the thing we have

[[email protected]]

Please add your name to the wiki page and we'll try and flag this to the developers.

[Sprocket]

Done mate ;D I was busy typing away as you posted both times :D ;)

[Sprocket]

Just to tie in with this http://www.vems.co.uk/forum/index.php?topic=184.msg1793#msg1793

:)

[miniminor63]

done:)