MAP sensor MOD...

And BTW, the first thing you should do is use a (decent) manner of monitoring the actual map;..

What are a GE diode and SI diode?

Rub87 said:

when you use a Si diode, you will see 1.25~1.3 bar, when using a zener in forward position (so not using the Zener effect) you will see 1.35 bar..

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will fit a 3.3v zener diode? is necessary to put a resistor too? what's forward position of zener?

google is your friend..

Ge = Germanium
Si = Silicon (Silicium)

Are types of diodes, Ge is known for lower forward voltage drop, look on google how a zener diode works..

yeah... but at first of thread the way was to put one leg of a 3.3v zener diode in +5v wire and the other leg connected to a resistor and connectd to chassis ground...
Now you are talking about of install a diode in serie in +5V wire... i will try this with one 3.3v zener diode in forward fosition... i hope don't blow anything!

Ehm yes, I tell you how to do it, but then you begin with putting resistors in series etc.. just stick with one way to do it and I tell you how, but not 3 ways at the same time..

I tried a zener diode in signal wire and boost sustained was 1.35bar but with huges boost spikes... when is boosting at 1.35bar+evry engine is faster but it's very difficult to drive it without big spikes(1.7-2.0bar)...

How did you place the zener?

I putted it in signal pressure wire...cutted wire and putted it beetween ends of wire... with negative part of zener to connector... when i put by the other way, no boost at any range...

then you've put it right.. maybe consider a remap?

It will be hard to fix the spikes with band aid mods like this..

Hey guys, what about some pictures to some of us learn something , lol .ok.

I don't know if i will keep this mod... car runs great at 1.35bar! can this mod to be more driveable with a boostvalve?

yes it should spike a bit less..

but... how i can to adjust my boostvalve? i tried with an air compressor but nothing... i set the outlet pressure of air compressor to 1.6bar and connect boostvalve to air compressor, when i can hear that air start to pass through boostvalve y lock the boostvalve nut... when i install it in car, no boost above 0.5bar!

maybe the vacuum of the N75 sucks it open? I've never used one, I rather like playing with N75 maps

Rub87 said:

maybe the vacuum of the N75 sucks it open? I've never used one, I rather like playing with N75 maps

Click to expand...

how to play with N75 maps? sounds great...

in the eeprom of your ecu..

Why don't you have the car shipped, it will drive so much better..

Rub87 said:

in the eeprom of your ecu..

Why don't you have the car shipped, it will drive so much better..

Click to expand...

I want to install Race520 nozzles, gt1852v turbocharger and 60mm downpipe before remap it... i hope in summer i will can do it...

Well, i tried all resistors and diodes possibles MAP mods in 2.5bar sensor and i can say that any of these mods worked fine for me...Crazy boost! too much boost spikes and using boostvalve!
The best way to go is with 3 bar map sensor and boostvalve for to adjust boost. I set mine to 1.3 and i haven't spikes above 1.4-1.5!!! A lot more stable,reliable and funny...
I put a lower value resistor for EVRY and when the evry switch is on i have a IQ of 1.6-1.8...i have to switch on EVRY when engine is started for to avoid engine light...

This is the best cheap combination for me after a lot of tries:
-MAF mod + EVRY (IQ 1.X) + 3 bar map + boostvalve

I can't see a lot of smoke at any moment... will be the EGTs too highs with a IQ of 1.x?or 1.4-1.5 bar is sufficient for to cool EGTs in the 1.X IQ range?

I will order my Race520 nozzles tomorrow, until i've got them, i will keep these cheap mods: too much faster than before, for sure!

Sorry if this has been beaten to death, I'm just curious.
Wouldn't a simple 2 resistor work to attenuate the signal to give similar output as 3 bar MAP? Except you could limit it a little better (for those with stock turbo, etc.)
I was thinking something like this. (sorry, not sure how to post a picture)

MAP pin 4 > 270 Ohm res > 2K Ohm res > ground
Tap between 2 resistors back to ecu

A POT could by used instead to tune it a bit better.
This gives about a 87% decrease in the signal.
I'm just not sure if this would work with the impedance characteristics of the MAP/ECU.
I realize this will mean cutting up the MAP cable, but its just a theory. I tested it on a bread board, and when the MAP reads a 4.1 V (about 2200 mbar) it will output 3.6 V (1900 mbar) which is requested on a stock ALH.
(PS, i know there are a million better ways to do this like tuning, zener diode, etc just curious about this electronic question)
Thanks for the replies!

it will work, but the problem is that the ecu needs lets say 2300mbar to go in limp mode, and at 1.5 bar relative boost you have 4.65v, now if you alter that voltage lower than the ecu limp mode treshold the ecu will never go into limp mode which can be tricky when you're not watching the boost gauge..

I don't have to worry about it requesting more than 1900mbar as I have a stock tune and that is all it requests. I've done this as I mentioned ealier and I have it set to 18 psi nicely. I used a POT to tweak the boost. No CEL's or limp modes. Running 4 months now without issue. Toss in the EVRY MOD and it's not a bad setup. I used a 555 timer with a relay to delay the connection of the EVRY on startup to avoid CELs.

so what is needed to go beyond 1.8 bar of boost with a 3 bar map sensor ?

car is tuned to 230 bhp with hybrid but my tuner wouldnt go beyond 1.8 bar boost even though hybrid is rated at 2.2 bar .

i have too much fuel and not enough air going in results in smoke on hard throttle

hollow said:

so what is needed to go beyond 1.8 bar of boost with a 3 bar map sensor ?

car is tuned to 230 bhp with hybrid but my tuner wouldnt go beyond 1.8 bar boost even though hybrid is rated at 2.2 bar .

i have too much fuel and not enough air going in results in smoke on hard throttle

Click to expand...

2.2bar until what rpm?

i have no idea . i was toying with the idea of fitting a 3.5 bar map sensor

as the voltage outputted will be lower at the same boost than the 3 bar one . so in theory i will get more boost than i currently have

more boost equalling more air - less smoke on wot

A tune will give you less smoke, the claimed 230hp is a little much for stock 130 injectors and a hybrid, most at the RR day a few months back got a dissapointing 215hp

I went to college in Donny!!

sorry didnt update profile my car is a 140 tdi a3 bkd engine

do have rolling road print out claiming 231.1 bhp

for a reputable company in uk

I was trying out these mods as my 3bar MAP seems to read wrong without modification (group 10 measuring blocks show a difference between baro and map pressure even when engine off but in ignition), as Jeff tuned me for 23 psi and I could never get above 21 psi. I had not much luck until I learned about voltage dividers! The calculations are not necessary, but they help you fine tune it quicker. I think a potentiometer with between 5,000 and 10,000 ohms is best as it won't strain the output of the MAF and a diode with a voltage drop of 2.7v is good. Most diodes are around 1.6 or 1.8v, which is ok too. I chose 2.7v, because that is where the 3 bar MAP is around 10 psi- past the surge point. In doing calculations of different pressures on my setup, the difference in real boost vs fooled map boost starts from 0 at 10 psi and goes up to 2 psi at 22 psi. This won't make a big jump like the typical diode mod or a pull down resistor setup.

Just be careful, start off with most of the resistance on the Ground side and watch that boost gauge while WOT in 3rd!
http://img405.imageshack.us/img405/8323/mapsensormodvoltagedivi.jpg

I there i have 2001 1.9tdi passat and i need a wiring sequence of the MAF can anyone help me?
Tanks

From old Tech4TDI website- which matches my diagram, but I drew pin 4 first. Your colors may vary.
Pin 1 - signal ground Brown/blue
Pin 2 - Temp output Grey/Green
Pin 3 - 5v supply and reference purple/red
Pin 4 - Pressure output yellow/black

I've also switched to a 1.8 V LED instead of the 2.7 V.