DIY_EFI Digest V5 #23
ECMnut at aol.com
ECMnut at aol.com
Sun Jan 16 14:33:18 GMT 2000
> G'day all,
> I'm fairly new to this news group, I've been lurking for about a week, and
> I've got a question about ECUs in general. I'm currently building an EFI
> computer for my 83 Pusar Exa turbo, and have the fuel running great,
> currently I'm working on spark.
Greetings Andy,
it's great to have you aboard..
There are two ways that the GM turbo
car ECMs handle timing.
1. Without using a MAP sensor, they rely on mass air flow & RPM
numbers to determine engine load (LV8). in the maf systems, they
assume "high air flow" + "low rpm" must
mean that the engine is heavily loaded.
The chip has a timing table that uses LV8 & RPM lookups.
2. With the MAP sensor system, they use a MAP vs RPM table
for the lookups.
Each system has its strong / weak points.
HTH
Mike V
.
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