a MAF too small

[Frederic Breitwieser]

> Frederick this is EXACTLY what I came up with as the theory. I had
> not considered the injector part though.. hmmm. I have been kicking
> this idea around for a good bit, I may have mentioned it on EFI list

Well, consider the injector portion an opportunity to learn from my mistake.
I didn't even think about doing anything injector wise, and the system leaned
out, knocked, and threw a rod.  3.8L V6 FWD Buick engine.  Very easy to do,
and it makes a nice "snap" noise too.

> you can bypass only what air you need to stop at a 253 reading..

Even my suggestion is not entirely complete.  If you double the airflow, and
double the fuel flow, you will have maintained the same mixture air to fuel.
Then of course, the MAF is maxed out at 1/2 of where it used to be RPM wise,
so one can increase the area of the maf's inner diameter by double, then the
MAF will record the new range - zero to double the old spec.  This works a
little better than the MAF bypass tube, but I recommended the bypass tube
because you can put a plastic ball valve in the bypass tube and adjust it - a
lot easier than machining a few MAF housings before you get it right.

Anyway, the only problem then becomes idle.  At idle, the MAF normally would
read, say, 30.  With the new housing, it would read 15, and probably flutter
its output due to turbulance and reversion in the MAF housing, thus your car
might idle if you are lucky.  You can compensate by cutting off the welded on
GM fuel pressure regulator, and replacing it and the fuel rails with an
adustable one, but then at this point, you're adding a lot more fabrication,
more places to adjust, and a lot more complexity.

If you have the ability to change the tables, you can simple scale the fuel
tables to match the new MAF readings.  Instead of 255 (from the MAF) being WOT
as a naturally aspirated engine, about 128-130 would be the new value.
129-131 through 255 would be with the supercharger adding flow above
atmospheric pressure.  Changing the code and the MAF housing seems to me to be
the absolute correct way to go, however with code changes, a lot of people get
stuck.  I being one of them.

Of course there is the $1500 Electromotive solution - totally programmable,
built in direct ignition, and it mounts on the firewall :)



>
> thats all you should do cause that will help the idle the most.. keep
> the velocity UP thru the MAF. The "side tube" was next after proving
> the concept with holes. If the holes dont have the desired effect.. a
> piece of hose and a clamp to seal it and only a minor battle scar to
> show for the effort  ;-) THanks
> Dave Z. www.delanet.com/~tgp