[MR2] MK1 ECU quesiton

[waynearndt]

Can you tell us dummies the difference between open & closed loop? You don't
have to bury me with too much detail, just a couple lines. ;)




---------- Original Message -----------
From: "Brian Knoblauch" <briank at glmotorsports.net>
To: <mr2 at mr2.com>
Sent: Fri, 28 Sep 2007 07:58:04 -0400
Subject: Re: [MR2] MK1 ECU quesiton

> Long Term and Short Term Fuel Trims (LTFT/STFT) are adjusted (on 
> modern computer controlled) cars when parts/weather/whatever changes 
> require the car to do so.  Only operates under closed loop, no 
> effect on open loop. Takes, at most, about 5 minutes and it's fully 
> adjusted.  That's the only thing I count as learning.  I don't even 
> count timing retard due to knock, since it'll try the same advance 
> next time you do the same thing, detect the knock all over again and 
> have to bring it back...  (The DSM algorithm is to drop 1/3 degree 
> of timing for each count of knock (and I suspect others are the same)
> , so you usually end up with just a flatter than normal timing curve 
> unless you have something that goes seriously wrong!).
> 
> --Brian
> http://www.glmotorsports.net
> 
> > There is NO learning capabilty. They measure sensor inputs and then
> > compare those inputs to preloaded maps. 99% of ecu's have zero learning
> > capability and will not magically adjust for new parts by resetting. That
> > is all urban myth. I have no idea where these rumors started and why so
> > many people belive it. The only learning I have ever seen on an ecu is
> > timing. For example a WRX will advance timing until it sees knock then go
> > back a few degrees.
> 
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------- End of Original Message -------