Hey guys, i been reading a lot, and i tought i had somethings figured out, i was today at some engine tunning clases (not the kind of tunning you're thinking about) and i got into a debate with a teacher because i said that our engines (mine is an OBD1 Accord LX F22B2) needed the MAP sensor to know how much air is coming in the engine so the engine will know how much gas to "inject", he says that is not true that all engines with computer controlled ignition doesn't need a map that they used the MAF, i know hondas don't have it, at least before not the new one, and i know that DSMs do use it.

So i'm a lil confused, can u guys help me get my toughts straight.

 

find vacuum pressure

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by hybridvteceg &raquo;</TD></TR><TR><TD CLASS="quote">find vacuum pressure</TD></TR></TABLE>

what does the ECU does with what the MAP senses? does it uses the MAP reading to know how much fuel to inject?

 

On Honda vehicles, the PGM-FI system is "speed-density" system. Basically, it uses the MAP and TPS sensors to determine engine load in order to calculate injector duration. Manifold Absolute Pressure is just another name for engine vacuum. The ECU also uses other sensors to modify injector duration, but MAP and TPS signals are the most critical, during closed loop operation.
Other vehicles that use the Bosch style system use the MAF sensor to determine engine load. The MAP and the MAF are two ways of telling the ECU how much air is going into the engine to help it decide how much fuel is required.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by b19coupe &raquo;</TD></TR><TR><TD CLASS="quote">On Honda vehicles, the PGM-FI system is "speed-density" system. Basically, it uses the MAP and TPS sensors to determine engine load in order to calculate injector duration. Manifold Absolute Pressure is just another name for engine vacuum. The ECU also uses other sensors to modify injector duration, but MAP and TPS signals are the most critical, during closed loop operation.
Other vehicles that use the Bosch style system use the MAF sensor to determine engine load. The MAP and the MAF are two ways of telling the ECU how much air is going into the engine to help it decide how much fuel is required.</TD></TR></TABLE>

I was right then. Thank you for taking your time to answer me, this is why i like HT that much.

 

also map sensors are generally used on turbo charged cars to sense boost as well as vacum... the maf is far more accurate for na though. Some use both. the stock honda map will read upto somewhere around 2bar (around 30 psi).

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by NonovUrbizniz &raquo;</TD></TR><TR><TD CLASS="quote">also map sensors are generally used on turbo charged cars to sense boost as well as vacum... </TD></TR></TABLE>

Yeah, i know that, that was the argument i try to use to explain myself.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by NonovUrbizniz &raquo;</TD></TR><TR><TD CLASS="quote">the maf is far more accurate for na though.</TD></TR></TABLE>

Really? i didn't knew that.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by NonovUrbizniz &raquo;</TD></TR><TR><TD CLASS="quote"> Some use both. </TD></TR></TABLE>

Like what cars? I want to learn about different manufacturers and their methods.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by NonovUrbizniz &raquo;</TD></TR><TR><TD CLASS="quote">the stock honda map will read upto somewhere around 2 bar (around 30 psi).</TD></TR></TABLE>

I tough stock MAP sensors could only read one bar

 

The statement about the TPS being a critical input is not accurate. The MAP and RPM are the 'main' two inputs for addressing the fueling and timing maps in memory, open or closed loop.

The TPS is used to A)tell the ECU when the throttle is closed for idling and fuel cut on decel, B)tell the ECU the rate of change for fuel enrichement, and C)tells the ECU when the throttle is wide open.

 

ya your right it's 11lbs of boost according to hondata... I thought it was 2 bar for some reason...

as far as which one's I can't remember I can find out though if you want...

MAF senses exactly how much air volume is flowing by the sensor... this in combination with an intake air temp sensor can give you just about as accurate a reading on quantity of air you can get (volume*density (at the temp iat sens. gives)... where as the map sensor just measures the air pressure not volume... while you can get VERY accurate readings from this they are not AS accurate as MAF...

hope that helps. sorry for the mis-information on the 2bar

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by EE_Chris &raquo;</TD></TR><TR><TD CLASS="quote"> The MAP and RPM are the 'main' two inputs for addressing the fueling and timing maps in memory, open or closed loop.
</TD></TR></TABLE>
RPM doesn't have much effect on the fuel side. If you were to take a snapshot of the injector pulsewidth, you wouldn't see much variation over the RPM range at wide open throttle. The injector pulswidth and the map voltage look almost identical when graphed.

Your right about the TPS though. It doesn't have much effect.

 

so, pretty much hondas need the MAP to calibrate how much fuel is needed. So, yes, hondas rely on MAP while DSM relies on MAF, is this right?

 

yes... simply put your teacher was dead wrong... you can feel more than confident going to class and telling him he's wrong and if he does a little research he'll see.

there is NO maf sensor on hondas they use the map sensor.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by GZERO &raquo;</TD></TR><TR><TD CLASS="quote">so, pretty much hondas need the MAP to calibrate how much fuel is needed.</TD></TR></TABLE>
Yes.

 

i hate realizing that i was correct and that the other person was wrong.
thanks guys, altough it would be nice to hear what other manufacturers do with their cars.

 

Ok.. I THINK that the buick grand nat has both a maf and a map (the famous gm 3bar map)...


ok yes it does... however once it's into boost it ignores it because the maf limit is 255grams/sec. apparently at that point it relies on the engine speed to calculate fuel flow...

Most cars just use pre-set maps to fuel the car and varies from those maps only slightly even in open-loop mode...

here's a link to where I confirmed the grand nat has a maf sensor... I know they have a map sensor.

grand-nat hack site

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by GZERO &raquo;</TD></TR><TR><TD CLASS="quote">... altough it would be nice to hear what other manufacturers do with their cars.</TD></TR></TABLE>
Seems like it's been 'traditional' for European cars to have MAF while Japanese had MAP sensors.

Saab & VW have used airflow sensors (MAF) of different types over the years. I think other Europeans did too, just because everybody uses Bosch.

The older lift-plate sensors like my old '82 & '86 VWs were almost like MAF sensors, because the force on that plate was proportional to flow & density together. Then in the mid-'80s Saab started using a hot-wire flow sensor. My '01 Saab has both - hot-wire MAF sensor along with a MAP sensor.

All of them get close, & use the O2 sensor to close the loop.

 

Isn't the GN MAP a 2-bar? The '89 Turbo T/A had the 3bar. I could be wrong.