MAF sensor up grade

NICO · Post by **NICO** » Wed May 12, 2004 6:45 am

i am just wondering if there is a up grade i can do.

As i walk threw a junk yard i see all these maf sensors all over the place they look all most the same as our turbo legacys, some of them have the same conectors and shape and style.

Is it possible to get one from a v8 car and wire it up to work on our cars it looks so easy, would it make more power, or will i blow up my ecu.

THAWA · Post by **THAWA** » Wed May 12, 2004 6:53 am

didn't vrg do something like this with a gm maf or something?

vrg3 · Post by **vrg3** » Wed May 12, 2004 6:57 am

THAWA, you may be thinking of my replacing the stock MAP sensor with a Chrysler MAP sensor...

Nico, it doesn't really make any sense to use a MAF sensor other than stock with the stock ECU. The sensor and ECU are a matched pair.

NICO · Post by **NICO** » Wed May 12, 2004 6:57 am

you guys post fast, so its not worth it then i was just thinking cuz they look the same, so it wont work and dont waste time and money on this

NICO · Post by **NICO** » Wed May 12, 2004 7:06 am

vrg3 u change the map sensor did it give you more power

where is the map sensor.

i got a extra ecu and maf sensor for my car, is there a place i can send it to get me more power

BAC5.2 · Post by **BAC5.2** » Wed May 12, 2004 7:30 am

Nowhere can you send your MAF to get you more power. The MAF simply measures the amount of air that goes through (actually, the hot-wire setup measures voltage to keep a wire at a certain temperature.)

The only worthwhile upgrade to the metering system would be a speed-density conversion (MAP based metering). It's not really better, well it has its advantages, but it's just more flexible and it bases fuel trims off of the same exact information that the ECU sees, rather than converting a voltage and "guessing."

I don't know that you could convert to Speed Density with the stock ECU though.

vrg3 · Post by **vrg3** » Wed May 12, 2004 4:39 pm

Nico, the Chrysler MAP sensor is just a cheaper alternative to the stock sensor. It's not better in any way. This is the writeup I did of it:

http://www.graphics.cornell.edu/~v/chrysler_map/

You could convert to speed density with the stock ECU if you really wanted to, but the amount of electronic complexity would be similar to that of a standalone ECU installation, since you'd still have to create a map of the engine's volumetric efficiencies at various manifold pressures and temperatures, and you'd still have to modify the map any time VE changed at all.

NICO · Post by **NICO** » Wed May 12, 2004 11:27 pm

wow vrg3 u are good, so if i change it over to that map sensor what will it do, does it give you more gas more power.

i red all your right up but i ant good with electrical so if i dont make cents let me no.

czo79 · Post by **czo79** » Thu May 13, 2004 1:05 am

emanage can change you over to map I believe...

vrg3 · Post by **vrg3** » Thu May 13, 2004 2:26 am

Nico - It won't make you any more power at all. It justs costs less, so if your stock MAP sensor breaks you might consider using the Chrysler part instead of buying a new Subaru part.

czo97 - An e-Manage has about the same complexity as a standalone ECU.

NICO · Post by **NICO** » Thu May 13, 2004 7:33 am

ok i was think i was going to get more power, but thanks vrg3 thats some good info to no,

thats $400 american it would be about $600 hundred canadian,

ya that whould hurt the bank flow

Brat4by4 · Post by **Brat4by4** » Thu May 13, 2004 8:48 pm

in case you haven't gotten Vikash's hints Nico... you need to look into going stand-alone. you will make massive power with just a little tuning and take those nitrous guys out left and right.

ultrasonic · Post by **ultrasonic** » Thu May 13, 2004 10:26 pm

NICO I WRX U wrote:wow vrg3 u are good, so if i change it over to that map sensor what will it do, does it give you more gas more power.

i red all your right up but i ant good with electrical so if i dont make cents let me no.

Nico... do you spell that way on purpose? It makes your posts really hard to read, and it makes you sound stupid. I've worked my way through some of your posts (with great difficulty) and I know you are not stupid.

NICO · Post by **NICO** » Thu May 13, 2004 11:16 pm

it just happens, not good with spelling and paragraph makeing

Brat4by4 · Post by **Brat4by4** » Fri May 14, 2004 4:00 am

he doesn't freakin speak english as a first language, how hard is that to understand?

imagine how your spelling and structure would look on a german bbs.

give the guy a break.

and Nico.... stand-alone... the only two words you need to think about now. everything else will pale in comparison if you get some good fuel maps in your car.

ultrasonic · Post by **ultrasonic** » Fri May 14, 2004 4:18 am

Brat4by4 wrote:he doesn't freakin speak english as a first language, how hard is that to understand? :? imagine how your spelling and structure would look on a german bbs. :roll:

give the guy a break.

Hey, break given. No offense intended. We all know people who write that way on purpose, it was just frustrating me. Apologies to Nico.

IronMonkeyL255 · Post by **IronMonkeyL255** » Fri May 14, 2004 7:48 am

Sorry to sound stupid here:

vrg3 - what you did was just switch from a Subaru MAP sensor to a 'Mini-Mopar' MAP sensor, correct? Then your ECU is still using the MAF sensor to determine fueling, right?

I'm just trying to figure this out.

What does the MAP sensor do on our cars? I didn't even realize we had one until reading this thread.....

vrg3 · Post by **vrg3** » Fri May 14, 2004 7:57 am

IronMonkeyL255 wrote:vrg3 - what you did was just switch from a Subaru MAP sensor to a 'Mini-Mopar' MAP sensor, correct?

Well, I also added a signal conditioner so that the signal from the Mini Mopar sensor would match the stock sensor's signal.

Then your ECU is still using the MAF sensor to determine fueling, right?

Primarily, yes.

What does the MAP sensor do on our cars? I didn't even realize we had one until reading this thread.....

Well, it's technically not just a Manifold Absolute Pressure sensor; it's a pressure sensor used to measure both manifold pressure and atmospheric pressure.

I know for sure of two uses the ECU has for the pressure sensor's signal: 1) to compensate for altitude (this includes any fuel/ignition changes as well as increasing boost), and 2) to detect an overboost condition so the ECU can cut fuel as a safety measure.

I do not know for sure whether or not the ECU also uses manifold pressure inputs when deciding how rich to make the fuel mixture and how much to retard ignition timing.

IronMonkeyL255 · Post by **IronMonkeyL255** » Fri May 14, 2004 8:04 am

Cool.

I was just making sure I understood what you had done.

Do you think there would be any way to force the ECU to use a MAP sensor instead of the MAF sensor? Maybe a signal converter to get it to 'read' the pressure as being the same as the airflow?

NICO · Post by **NICO** » Fri May 14, 2004 8:27 am

you no what there is to many sensors in this car to fool around them,

id have no clue where to start with stand alone, then id have to get a laptop plus the stand alone, i think i would blow the motor in a week, how about a chip or a flashing of the ecu.

i got a 88 323 gtx, this guy lived 2hrs away in another city, he sells every where in the world, i got a ecu from him i pluged it in my mazda wow it was like the missing pice. anyone no of anyone that has one for a legacy turbo 91

NICO · Post by **NICO** » Fri May 14, 2004 9:42 am

vrg3 you are good at eletronics can you help me hook back up my hks super afr

i put it back on and it wont work right, i mixed up a couple of wires on the map sensor and tps sensor. i am going to right down the way i have them you correct me cuz i dont no its trickey stuff.

vrg3 · Post by **vrg3** » Fri May 14, 2004 4:26 pm

IronMonkeyL555 - You could generate a synthetic airflow signal if you wanted. Like I said, though, it'd be similar in complexity to an aftermarket ECU. You'd need to install a pressure sensor that only reads from the manifold (unless you weren't planning on exceeding 2 bars absolute pressure and you wanted the fuel mixture to get screwy whenever the ECU was sampling barometric pressure like old Chrysler turbos did). Then you'd need to install a manifold absolute temperature sensor. Then you'd need to make a controller that reads in the tach signal (to compute RPM), the MAP signal, and the MAT signal, and looks up the engine's volumetric efficiency in a table, and then runs the airflow through the inverse of the MAF sensor's transfer function. Then all you'd have to do is fill in the table of VEs.

Nico - You're right that a standalone ECU is an easy way to destroy the motor, since you need a lot of skill and experience to tune it.

Right now there's no aftermarket plug-in ECU for our cars. Yet.

If you really want to do it right though you might consider hiring someone who knows what he's doing to help you install and/or tune an aftermarket standalone ECU.

If you write down everything you did and can get me a copy of the AFR's manual, I'll try to figure out if it's right or not.

IronMonkeyL255 · Post by **IronMonkeyL255** » Fri May 14, 2004 6:03 pm

So it's do-able, but not practical.

Now I wonder how long I can go before having to go stand-alone......

NICO · Post by **NICO** » Fri May 14, 2004 10:57 pm

vrg3 this is what it tells me to do, i must find the throttle position signal wire and tap in to it, this is where it gets crazy

1. it tells me to tap in to the cut pressure sensor/ air flow signal wire
connect the yellow safr wire to the portion of wire going to the factroy ecu (afs output).

2. then connect the white safr wire to the portion of wire poing away from the ecu (afs input)

3. then when i do all that it asks for this
hot wire (0-5v) off off
hot wire (5-0v) on off
karmen vortex off on
pressure sensor on on

4. then it ask if the safr eids function can be set active or inactive via dip switch 3. the eids function is not applicable on speed-density applications and should be switch to off positon

NICO · Post by **NICO** » Fri May 14, 2004 11:06 pm

it also says to go direct to the ecu u

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MAF sensor up grade

MAF sensor up grade