ecu voltage problem

[Frederic Breitwieser]

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Sounds like you have some interference from something, as I suggested 
before a 'scope on the Vcc line will show exactly what kind of garbage if 
any, is leaking into your system.  Check on each side of the 7805 
regulator.  A simple choke/inductor might solve the problem, maybe 
relocating the EFI computer might help, maybe changing to low noise spark 
plug wires, maybe your alternator is creating electrical "whine", possibly 
the shielding on your EFI box is not sufficient, or worse, a combination of 
the above in small amounts.

Fred

-----Original Message-----
From:	S. Lastuka [SMTP:kicker at u.washington.edu]
Sent:	Wednesday, April 30, 1997 3:23 PM
To:	diy_efi at coulomb.eng.ohio-state.edu
Subject:	RE: ecu voltage problem

We are using a 7805 1 amp voltage regulator.  We also tried a 1000 uF cap
between 12 volts and ground to no avail.  I am going to run over to the
ECU and analzye the ground situation since we had the computer
running the engine on a stand but as soon as it was in the car it
crapped out.  Other information: the regulator seems to put out 5 Volts
down to a 7-8 volt input.  The cmos in the 68hc11 will work down to 4 1/2
volts with little problem and can probably drop a bit below that
sometimes. 

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