ecu voltage problem

[S. Lastuka]

Our system seems to be running quite well at the moment (we are
tuning the maps). It is a tps system.  Very simple.  We are running a 600
cc yamaha (YZR i think).  The computer is based on RPM/tps because we have
never done this kind of thing before and that seemed to be the simplest
way to do it.  Last year the team used a Haltech computer which used MAP
and delta tps.  This system was effective but had a lot of starting
problems and would not idle below 2500-3000 rpm.  Our system this year will 
loaf the engine along at 1000 rpm.  I think this
is because a MAP system gets a fluctuating pressure signal at idle.  On
the other hand the tps signal is constant and also holds the pulse width
constant thereby letting the engine run on what it gets and not have a
computer constantly adjusting to what the engine wants.  
This of course could cause the engine to running lean or rich so that is
why we probably have to do a lot more tuning.  I am speculating on all of
this since i too am an EE and know a relatively small amount about
engines.
Sean    

On Sat, 3 May 1997, Thor Johnson wrote:

> On Wed, 30 Apr 1997, Kurt Bilinski wrote:
> 
> > At 08:32 AM 4/30/97 -0700, you wrote:
> > >I am an FSAE student and we built an EFI computer for the competition.
> > >There seems to be a problem running it off the car's power supply, ie the
> > >battery.  When it is hooked up to the battery the computer holds pulse
> > >widths at around 1 ms per revoltution regardless of throttle position.
> > >When we hook it up to the standard voltage regulator used for testing in
> > >the lab the car works perfectly with full rpm and throttle range, but
> > >can't move because it is attached to an extension cord.  We're using a
> > >68hc11 processor.  If anyone has had any weird voltage problems like this
> > >any help would be appreciated.  Thank you,
> > >
> > Get the EE guys over for some serious shielding.  Use a scope to check the
> > Vcc lines.  You're getting noise feeding in from somewhere.  They need to
> > do bypassing on all the supply lines.
> > 
> > It's kind of a big deal, maybe get one of the EE prof's over who's good at
> > EMI, the students probably won't know.
> 
> Been too busy trying to tune ours to read this quickly.  I got around 
> that on our EFI system by placing a 10,000uF cap accross the supply, 
> after a diaode.  Originally this was to protect agains brownouts during 
> cranking, but I haven't had any problems.
> 
>   Iw ould be interested in hearing some of the details of your system... 
> Mine is a MAP based system with lookup tables for delta-throttle, ECT, 
> and others, but it seems to be very difficult to tune properly (I am 
> strictly an EE, and have little/no car experience).
> 
> Any pointers?
> 
>                 Thor Johnson
>           johnsont at falcon.cs.mercer.edu
>      http://falcon.cs.mercer.edu/~johnsont
>                                                     
>          Have you seen the WarpMap lately?                    
>     http://falcon.cs.mercer.edu/~johnsont/warpmap  
> 
> 
>