JDM / SCT Tuner Now Shipping

[FSM06]

all throttle map table lookups go to 100%, and engine power is controlled by fuel inputs instead of throttle opening..

I am a little concerned about this comment as well, since fuel delivery is completely computed by the mass of air entering the engine. The Mass Air Flow sensor is the most pertinent input to the PCM that provides air flow and, more importantly, load information to calculate fuel delivery. The opening or closing of the throttle plate is in direct relation to the mass of air read by the MAF sensor. Any additional info that would help with this theory?

 

[BigJ]

I wonder if frog is thinking MAP, not MAF...

 

[FSM06]

I wonder if frog is thinking MAP, not MAF...

I don't believe so J since throttle mapping is different than what we refer to as a Manifold Absolute Pressure sensor or MAP. MAP's have not been used on gasoline engines (at least on Ford vehicles) since the mid to late 90's I believe.

 

[BigJ]

Roger that. We live by those things in the Dodge world, even today (and hate every minute of it; I helped pioneer tuning of the 3rd gen HEMIs and they sure can make life tough.)

 

[frogslinger]

Nah, it is not MAP... though I think a lot of people run map sensor down in AU...

I do not remember what video it in but one of the early videos says that in offroad mode the throttle is locked open so that the response from the pedal is truly linear.

I do not see why this would affect your MAF... all your MAF does is measure the drop in temperature of a wire with a set voltage running through it... from that it works out how much air is running through it... I am not sure how that would be affected by the actual throttle position... your volume of air is not really what your throttle is trying to control (though it does), what it is trying to control is velocity.

Even with your throttle locked open I see no problem with controlling the vehicle entirely with spark and fuel injectors... you will still be getting an accurate reading from the MAF, you can control Air Fuel ratio with you injectors, and when it comes time to slow down you simply cut fuel and spark... you go hyper lean immediately, but that is not an issue if you have light to zero load...

I may be way off... I am no engine expert... more a computer/radio guy... and I am no expert there either... there may be a huge error in my theory, but I am not seeing it.

I know BMW went to a throttleless design on their sub 2 liter car in europe, though I think they faked it by varying valve lift... there are a bunch of other throttleless designs out there...

I may have seen one thing something and made a jump that was incorrect though.

 

[MarkT]

Frog,

The throttle isn't "locked open" in off road mode on the Raptor... (except maybe on Brian's.):thumbsup:

(As far as I know, that's a feature only Toyota is considering... )

What they probably meant to say in the video was that the throttle pedal response was "linear". Which means that when you press the pedal 25%, the throttle plate opens 25%. 50% - 50%... 75% - 75%... 100% - 100%.

Which, believe it or not, is not always the case. Even back in the days of carburetors and mechanical linkages some manufacturers rigged the throttle to open further sooner than the pedal position would make you think. For example, pressing the pedal 25% would actually open the throttle plate 50%! When the pedal was halfway down, the throttle might be open 75%... and then the last 50% of pedal travel only opened the throttle plate 25%.

This kind of non-linear throttle gives the driver the impression of "more power" because a little press of the pedal from idle actually results in a big movement of the throttle plate.

Now, in the days of "drive by wire", this principle could be taken to make the throttle respond to the pedal any way the tuner wanted to. (An aftermarket tune could use this feature to "fool" a lot of people into thinking they got more power when really the throttle was just opening further quicker.)

As far as "throttleless" gasoline engines like the BMW? BMW uses the intake valves to control the amount of air allowed into the engine. At idle, the intake valves barely open. At full throttle, the intake valves open fully. (BTW, BMW has been using this technology for at least 10 years on their engines here in the US...)

To control the power on a gasoline engine, you control how much air is allowed into the engine. A gasoline engine requires the correct air/fuel mixture at all times. Period. Too lean will overheat and burn pistons. Too rich will waste gas and possibly cause damage by washing the oil off the cylinder walls. Go too far rich or lean and even if you don't damage the engine, it won't run.

The throttle plate on the 5.4 controls the air into the engine and therefore the power. The engine management system... all the sensors, etc... give the computer feedback so it can add just the right amount of fuel and spark for the conditions.

Mark

 

[FSM06]

Just FYI, an individual on the "other site" just posted that he had run the tuner for a week and was planning on returning it for a refund. Was not impressed at all.

 

[BigJ]

Just FYI, an individual on the "other site" just posted that he had run the tuner for a week and was planning on returning it for a refund. Was not impressed at all.

Well that's not good news.

 

[Falcon]

I am looking at customizing some factory black wheels with orange simu-beadlocks

Now THAT will look sweet!

Falcon

 

[Falcon]

What the hell IS this thing BigJ? It skeers me when I am trying to go to sleep! <G>

Falcon