Solutions to EFI interference Problems on Saab 99

[bcroe at juno.com]

Problems like that are hard to fix at a distance.  The 
general idea is to shield the circuit, use good grounding
internally, and filter any wires going in/out to only pass
the minimum frequency needed to operate.

Bruce Roe

On Tue, 2 Oct 2001 13:33:42 +1000 "David Sackett"
<david.sackett at optusnet.com.au> writes:
> 
> I have been having trouble with accurate measurement of RPM and I 
> believe it
> is due to interference from the ignition system. 

> If the engine is running at 1000rpm
> occasional values of 3000, 5500 & 15000 will be calculated by the 
> computer.
> I thought that the input and power supply filtering I had designed 
> was
> inadequate so I constructed a new circuit board based on the 
> megasquirt's
> power supply, coil based external interrupt trigger and TPS input 
> (thanks
> for the design Bowling and Grippo). I still get the same 
> interference!

> David
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