Posted by dsc-ky on May 21, 2008, 9:13 am
If you were to add a restrictor plate to the air intake of a modern
EFI vehicle, is the fuel management system smart enough to reduce the
fuel accordingly and keep things in balance?
If so, could that result in better mileage?
If not, I suspect it would run really rich and start throwing engine
codes all over the place?
Posted by Volker Bartheld on May 21, 2008, 11:07 am
Hi!
> If you were to add a restrictor plate to the air intake of a modern
> EFI vehicle, is the fuel management system smart enough to reduce the
> fuel accordingly and keep things in balance?
It should, if the restriction isn't putting things way off specifications.
I would try it out (with lambda/CO readings) and put such a plate between
the air-(mass)flow meter and the throttle valve, so it's more or less a
"resistor" connected in series with the throttle valve. Unfortunately, the
latter usually has a TPS (position sensor) which will report wild values if
you're whacking the throttle and still not a sufficient air (mass) flow.
So the better choice would be to restrict throttle valve operation so it
doesn't open all the way up. But that would restrict power/torque instead
of the injected amount of fuel.
> If so, could that result in better mileage?
Most probably: no. Except if you're still able to operate the engine close
the the point of maximal efficiency after the mod. If not (and the driver
goes FWO all the time because he has a certain feeling of power delivery),
it'll probably even consume more. If an engine is designed for a certain
output and you restrict it to (a lot) below, it'll consume more.
Restricting a FI system normally involves tweaking the engine
characteristic map in the computer (=software job) plus a mechanic
restriction.
> If not, I suspect it would run really rich and start throwing engine
> codes all over the place?
It might complain about inconsistencies:
* Air flow doesn't match TPS-value
* Lambda values might be way off
* Revs won't go up as fast as expected
etc.
If it's only for fuel saving, you could try to visualize the injected
amount of fuel instead of restricting it. That way, there's a feedback to
the driver. Might be available as an add-on, might not.
HTH,
Volker
--
@: I N F O at B A R T H E L D dot N E T
3W: www.bartheld.net
Posted by XR650L_Dave on May 21, 2008, 12:37 pm
> If you were to add a restrictor plate to the air intake of a modern
> EFI vehicle, is the fuel management system smart enough to reduce the
> fuel accordingly and keep things in balance?
> If so, could that result in better mileage?
> If not, I suspect it would run really rich and start throwing engine
> codes all over the place?
If you really want to mess with something, adding intake length might
move the torque peak down in the rev range a little bit, at the
expense of peak power.
What kind of engine, what kind of throttle-body? (2 round throttle
plates, 1 round plate, 1 oval plate, etc).
Dave
Posted by dsc-ky on May 21, 2008, 9:04 pm
> > If you were to add a restrictor plate to the air intake of a modern
> > EFI vehicle, is the fuel management system smart enough to reduce the
> > fuel accordingly and keep things in balance?
> > If so, could that result in better mileage?
> > If not, I suspect it would run really rich and start throwing engine
> > codes all over the place?
> If you really want to mess with something, adding intake length might
> move the torque peak down in the rev range a little bit, at the
> expense of peak power.
> What kind of engine, what kind of throttle-body? (2 round throttle
> plates, 1 round plate, 1 oval plate, etc).
> Dave
5.3 gm...
Posted by JayC on May 21, 2008, 12:54 pm
> If you were to add a restrictor plate to the air intake of a modern
> EFI vehicle, is the fuel management system smart enough to reduce the
> fuel accordingly and keep things in balance?
Yes.
> If so, could that result in better mileage?
No. You would get a peak power decrease though. If you want to do an
experiment, stick a piece of paper in your airbox on top of your
airfilter.
JayC
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> EFI vehicle, is the fuel management system smart enough to reduce the
> fuel accordingly and keep things in balance?