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Tue Jun 05, 2012 1:36 am

My wife's favorite joke:

Three dumb guy's are having a conversation. One poses this question to the others: What was the greatest invention of ALL time?

The first one thinks a bit and then says: "We'll that must be FIRE! 'Cause before fire we were always cold, and we had to eat our food raw or uncooked . . ."

The second guy scratches his head and exclaims: "The WHEEL! 'Cause that lead to cars and skateboards and such . . ."

The third guy thinks real hard, them blurts out: "The THERMOS BOTTLE!"

The other two shake their heads in disbelief, and ask him how he could possibly consider that to be anywhere near as great an invention as either fire or the wheel.

The third guy responds: "Because it can be bitter cold outside, but your hot coffee stays hot inside it all day long!"

"So?" they respond.

"And if it's 100 degrees outside all day, it'll still keep your iced tea cold for you for hours!"

". . . So?" they respond again.

'"Well," says the third guy in a frenzy of awe and amazement . . . "How do it know?"

:lol: :lol: :lol: :lol: :lol: :lol: :lol:

My question is this:

After scouring my greasy brown copy of Mr. Bentley's guide to the care and feeding of the Type 3, I have yet to come across precisely how the ACVW engine FI understands how to compensate for altitude changes in the fuel mixture.

I mean, if you have to readjust your carbureted engine settings as you navigate from higher to lower locales, why don't you need to do this in a FI engined ACVW?

And so, dear fellow Sambanistas, I humbly submit to you all this truly vexatious conundrum:

"How do it know?"

Tue Jun 05, 2012 1:37 am

Square One wrote: My wife's favorite joke:

Three dumb guy's are having a conversation. One poses this question to the others: What was the greatest invention of ALL time?

The first one thinks a bit and then says: "We'll that must be FIRE! 'Cause before fire we were always cold, and we had to eat our food raw or uncooked . . ."

The second guy scratches his head and exclaims: "The WHEEL! 'Cause that lead to cars and skateboards and such . . ."

The third guy thinks real hard, them blurts out: "The THERMOS BOTTLE!"

The other two shake their heads in disbelief, and ask him how he could possibly consider that to be anywhere near as great an invention as either fire or the wheel.

The third guy responds: "Because it can be bitter cold outside, but your hot coffee stays hot inside it all day long!"

"So?" they respond.

"And if it's 100 degrees outside all day, it'll still keep your iced tea cold for you for hours!"

". . . So?" they respond again.

'"Well," says the third guy in a frenzy of awe and amazement . . . "How do it know?"

:lol: :lol: :lol: :lol: :lol: :lol: :lol:

My question is this:

After scouring my greasy brown copy of Mr. Bentley's guide to the care and feeding of the Type 3, I have yet to come across precisely how the ACVW engine FI understands how to compensate for altitude changes in the fuel mixture.

I mean, if you have to readjust your carbureted engine settings as you navigate from higher to lower locales, why don't you need to do this in a FI engined ACVW?

And so, dear fellow Sambanistas, I humbly submit to you all this truly vexatious conundrum:

"How do it know?"

Manifold pressure sensor.

Altitude affects vacuum:
http://www.anver.com/document/vacuum%20lifters/atmospheric%20pressure.htm

Tue Jun 05, 2012 6:01 am

Tram wrote: Square One wrote: My wife's favorite joke:

Three dumb guy's are having a conversation. One poses this question to the others: What was the greatest invention of ALL time?

The first one thinks a bit and then says: "We'll that must be FIRE! 'Cause before fire we were always cold, and we had to eat our food raw or uncooked . . ."

The second guy scratches his head and exclaims: "The WHEEL! 'Cause that lead to cars and skateboards and such . . ."

The third guy thinks real hard, them blurts out: "The THERMOS BOTTLE!"

The other two shake their heads in disbelief, and ask him how he could possibly consider that to be anywhere near as great an invention as either fire or the wheel.

The third guy responds: "Because it can be bitter cold outside, but your hot coffee stays hot inside it all day long!"

"So?" they respond.

"And if it's 100 degrees outside all day, it'll still keep your iced tea cold for you for hours!"

". . . So?" they respond again.

'"Well," says the third guy in a frenzy of awe and amazement . . . "How do it know?"

:lol: :lol: :lol: :lol: :lol: :lol: :lol:

My question is this:

After scouring my greasy brown copy of Mr. Bentley's guide to the care and feeding of the Type 3, I have yet to come across precisely how the ACVW engine FI understands how to compensate for altitude changes in the fuel mixture.

I mean, if you have to readjust your carbureted engine settings as you navigate from higher to lower locales, why don't you need to do this in a FI engined ACVW?

And so, dear fellow Sambanistas, I humbly submit to you all this truly vexatious conundrum:

"How do it know?"

Manifold pressure sensor.

Altitude affects vacuum:
http://www.anver.com/document/vacuum%20lifters/atmospheric%20pressure.htm

:lol:

Tue Jun 05, 2012 2:34 pm

Great link Tram.

Now if I could just get mine running to find out. :?

Mike

Tue Jun 05, 2012 2:37 pm

Tram is right to a certain degree, yes MAP is affected by altitude but it is not a closed loop system so there is no compensation for it while your driving. Ljet had a optional baro module you could plug into the ecu to give you real time baro readings. I'm using speed density on my megasquirt (djet uses speed density too), i had to add another pressure sensor and check the box for baro correction. With speed density the baro readings allow the computer to compensate for the reduced back pressure of the exhaust since the air is thinner at elevation. For our cars that is really splitting hairs, but I like it even though high elevation for me is 300ft. I have it on closed loop right now so theoretically I don't even need the extra sensor since it is already correcting for the thinner air. BTW I got the sensor for about $13 and I have a bit of an addiction to hotrodding the MS :oops:

Tue Jun 05, 2012 2:54 pm

supaninja wrote: Tram is right to a certain degree, yes MAP is affected by altitude but it is not a closed loop system so there is no compensation for it while your driving. Ljet had a optional baro module you could plug into the ecu to give you real time baro readings. I'm using speed density on my megasquirt (djet uses speed density too), i had to add another pressure sensor and check the box for baro correction. With speed density the baro readings allow the computer to compensate for the reduced back pressure of the exhaust since the air is thinner at elevation. For our cars that is really splitting hairs, but I like it even though high elevation for me is 300ft. I have it on closed loop right now so theoretically I don't even need the extra sensor since it is already correcting for the thinner air. BTW I got the sensor for about $13 and I have a bit of an addiction to hotrodding the MS :oops:

Eh? If there's "no compensation for it" why is it there?

Tue Jun 05, 2012 4:01 pm

He had me lost at "Tram is right to a certain degree . . .

Tue Jun 05, 2012 4:02 pm

He had me lost at "Tram is right to a certain degree . . .

Tue Jun 05, 2012 6:07 pm

in all seriousness -- early FI systems like D-jet used an open loop design but Nick you're wrong that the closed vs open loop is what makes the adjustment -- in reality it makes the fine correction at all times for various contributing factors, irrespective of the altitude per se, though it is not excluded from stated contributing factors. furthermore, its really a fine adjustment for emissions and inefficiencies sake, not because without it you lose the ability to compensate for altitude. the initial adjustment is handled totally by the initial readings from either the MAP or the AFM, though IIRC AFM's are less accurate in altitude adjustment alone than is a MAP, while a MAP is less accurate/responsive to load/speed transitions than an AFM.

Tue Jun 05, 2012 11:40 pm

JSMskater wrote:

in all seriousness -- early FI systems like D-jet used an open loop design but Nick you're wrong that the closed vs open loop is what makes the adjustment -- in reality it makes the fine correction at all times for various contributing factors, irrespective of the altitude per se, though it is not excluded from stated contributing factors. furthermore, its really a fine adjustment for emissions and inefficiencies sake, not because without it you lose the ability to compensate for altitude. the initial adjustment is handled totally by the initial readings from either the MAP or the AFM, though IIRC AFM's are less accurate in altitude adjustment alone than is a MAP, while a MAP is less accurate/responsive to load/speed transitions than an AFM.

. . .Huh?

Tue Jun 05, 2012 11:46 pm

Square One wrote: JSMskater wrote:

in all seriousness -- early FI systems like D-jet used an open loop design but Nick you're wrong that the closed vs open loop is what makes the adjustment -- in reality it makes the fine correction at all times for various contributing factors, irrespective of the altitude per se, though it is not excluded from stated contributing factors. furthermore, its really a fine adjustment for emissions and inefficiencies sake, not because without it you lose the ability to compensate for altitude. the initial adjustment is handled totally by the initial readings from either the MAP or the AFM, though IIRC AFM's are less accurate in altitude adjustment alone than is a MAP, while a MAP is less accurate/responsive to load/speed transitions than an AFM.

. . .Huh?

I don't know either. All I need to know is it works. :lol:

Wed Jun 06, 2012 12:17 am

Tram wrote: Square One wrote: JSMskater wrote:

in all seriousness -- early FI systems like D-jet used an open loop design but Nick you're wrong that the closed vs open loop is what makes the adjustment -- in reality it makes the fine correction at all times for various contributing factors, irrespective of the altitude per se, though it is not excluded from stated contributing factors. furthermore, its really a fine adjustment for emissions and inefficiencies sake, not because without it you lose the ability to compensate for altitude. the initial adjustment is handled totally by the initial readings from either the MAP or the AFM, though IIRC AFM's are less accurate in altitude adjustment alone than is a MAP, while a MAP is less accurate/responsive to load/speed transitions than an AFM.

. . .Huh?

I don't know either. All I need to know is it works. :lol:

I always say:
When in doubt - go with the big monkey!

BTW, nobody. . . NOBODY has yet to explain: How do it know?

Wed Jun 06, 2012 12:38 am

Square One wrote: Tram wrote: Square One wrote: JSMskater wrote:

in all seriousness -- early FI systems like D-jet used an open loop design but Nick you're wrong that the closed vs open loop is what makes the adjustment -- in reality it makes the fine correction at all times for various contributing factors, irrespective of the altitude per se, though it is not excluded from stated contributing factors. furthermore, its really a fine adjustment for emissions and inefficiencies sake, not because without it you lose the ability to compensate for altitude. the initial adjustment is handled totally by the initial readings from either the MAP or the AFM, though IIRC AFM's are less accurate in altitude adjustment alone than is a MAP, while a MAP is less accurate/responsive to load/speed transitions than an AFM.

. . .Huh?

I don't know either. All I need to know is it works. :lol:

I always say:
When in doubt - go with the big monkey!

BTW, nobody. . . NOBODY has yet to explain: How do it know?

See my first post under your OP.

Now, the only question remaining is Why do it care?

Wed Jun 06, 2012 8:06 am

Square One wrote:

BTW, nobody. . . NOBODY has yet to explain: How do it know?

jesus christ just google it. :roll:

http://en.wikipedia.org/wiki/MAP_sensor

Wed Jun 06, 2012 10:02 am

The old and new efi systems use 4 basic sensors to run.
Map or maf... Map reads the vacuum or pressure in the intake to measure air injested. The maf measures the rate of air flow past its sensor to measure the air injested.
Coolant temp sensor...to tell when the engine warms and to adjust for air temp compensation from the heat in the head.
Air temp sensor... Tells how hot the air is and that helps determine how dense the air is. Remember... More air more power.
Tps... To tell the angle of the throttle plate and the load on the engine.

The early fuel injection uses a map sensor to measure the pressure in the manifold. At full throttle at sea level that pressure is 14.7 lb/in2 same as when the engine is off. That means that a clomun of air from the ground to space that is 1 sq inch weighs 14.7 lbs. now, the higher you go the less air is sitting on the square inch and so the pressure decreases. The air pump you call an engine creates a low pressure system inside itself and relies on outside air pressure to refill or equalize the manifold and the reading you get on a gauge is a false reading of pressure but is easier to understand.

So the pressure read by the map tells how much air is in the manifold and at higher elevations you have less pressure in the manifold.

Hope this helps.

Wed Jun 06, 2012 12:03 pm

JSMskater wrote: Square One wrote:

BTW, nobody. . . NOBODY has yet to explain: How do it know?

jesus christ just google it. :roll:

http://en.wikipedia.org/wiki/MAP_sensor

Excuse me, Heathen? Don't make me go all Catholic on your ass. :evil: (and no priest jokes from the peanut gallery, please.)

Wed Jun 06, 2012 1:27 pm

Tram wrote: JSMskater wrote: Square One wrote:

BTW, nobody. . . NOBODY has yet to explain: How do it know?

jesus christ just google it. :roll:

http://en.wikipedia.org/wiki/MAP_sensor

Excuse me, Heathen? Don't make me go all Catholic on your ass. :evil: (and no priest jokes from the peanut gallery, please.)

And here I thought it was "black magic" (aka Satan working over time). :twisted: And judging from ALL the pages in the FI sticky, I'd have to agree with it. :wink:

Wed Jun 06, 2012 2:08 pm

Tram wrote: Don't make me go all Catholic on your ass. :evil: (and no priest jokes from the peanut gallery, please.)

...no one has to-it's its own joke. :lol:

Wed Jun 06, 2012 3:36 pm

Everybody sing along:

(ah one and ah two . . .)

Give me that old time religion,
Give me that old time religion
And it’s good enough for me.

It was good for our mothers.
It was good for our mothers.
It was good for our mothers.
And it’s good enough for me.

Refrain

Makes me love everybody.
Makes me love everybody.
Makes me love everybody.
And it’s good enough for me.

Refrain

It has saved our fathers.
It has saved our fathers.
It has saved our fathers.
And it’s good enough for me.

Refrain

It will do when I am dying.
It will do when I am dying.
It will do when I am dying.
And it’s good enough for me.

Refrain

It will take us all to heaven.
It will take us all to heaven.
It will take us all to heaven.
And it’s good enough for me.

Refrain

Wed Jun 06, 2012 3:44 pm

:lol: :lol: