Y is honda civic got more hp then lanos?

[buddha102]

yea the MAP sensor always confuses me...

[PrecisionBoost]

In what way?

A MAP sensor is simply a ceramic element that senses pressure.

The thinner the element the more it will flex and thus react to pressure.

So a 1BAR MAP is nice and thin.... it goes from 0V at high vacuum to 5V at atmospheric pressure which is 14.7psi.

So when were talking absolute pressure.... a perfect vacuum is 0PSI and the regular air pressure you and I have on us at all times is 14.7 PSI thanks to all the 100km of air above us pushing down on us here on the earth's crust.

That is to say when the engine is at 0psi of boost the 1 BAR Map is at 5V

But... because the element is thin and it is only designed to go to 14.7 PSI ( absolute pressure ) it will crack and break no too long after that.

Some will allow for 4psi of boost ( 18.7psi total pressure ) and others may survive up to 7psi of boost ( 21.7psi total pressure )

The 2BAR MAP is good to 29.4 PSi and can also go a little ways past that rating.... probably 35psi of total presure.

Keep in mind that 1 BAR = 14.7 PSI...... so a 1BAR is good for regular atmospheric absolute pressure

A 2 BAR sensor is capable of our standard 14.7PSi atmospheric plus an additional 14.7PSi of turbo boost for a total of 29.4PSI.

2 BAR sensor flexes less at 0psi of boost ( 14.7PSi total ) and thus it only puts out about 2.5V at that level.... where as a 1 BAR would be putting out 5V

3 Bar is even thicker and can take 14.7PSi + 29.4Psi of boost for a total of 44.1 PSi of total pressure.... and again it's probably going to be fine at 50PSi of total pressure ( so roughly 35PSi of boost )

at regular atmospheric a 3 Bar will only be putting out around 1.67V .... at 29.4 PSI of total pressure ( 14.7psi boost) it will be putting out around 3.33 V


So.... last thing.... with a 1BAR sensor it might be able to handle 5psi of boost but the voltage will create issues.

First off the ECU will freak out when it sees a full 5V.... with a naturally aspirated vehicle it most likely will only ever see 4.9V from the MAP

So.... when it sees more than 4.9V the ECU think's the MAP is damaged and sets a check engine light.... then it ignores the MAP completely and throws craploads of fuel at the engine to keep it from destroying itself.

So... again.... boosting a 1 BAR factory MAP sensor will cause a check engine light in most cases.

Then we have the breaking issue.... which I already explained.

Lastly the ECU will not add fuel once the MAP passes 4.9V.... quite simply it should never see boost.... so quite often there are no maps to help the ECU once the pressure goes above atmospheric.

That is to say if you force in 7psi you should be adding 50% more fuel but the ECU doesn't know that... it might only add another 5% more fuel and bang.... there goes your engine because it's running lean


What a check valve does is it shuts things off when they hit 0psi of boost ..... that way the ECU doesn't freak out typically.... and you don't break the ceramic sensor element inside the MAP sensor.

With a good Check valve it will lock things up when boost hits and then it will allow the MAP sensor to see vacuum immediately after you let off the throttle.

Not all check valves are made equal.... some do not return vacuum to the MAP right away and cause other issues.

The Synapse engineering "missing link" check valve is really good.... it's specifically designed for this exact application


So... blocking a 1 BAR map from seeing boost is good.... you make up for this issue and add more fuel to the system by one of three things ( or a combination of all three ) :

1) Larger injectors
2) Higher fuel pressure
3) Aftermarket injector controller

So just so we are clear dropping in a check valve will save the MAP and make sure the ECU only sees what it expects to see...... without a check valve you risk damage and the ECU won't know what to do anyways when it sees boost.

Lastly.... if you install a 2BAR sensor into a car/ECU designed for a 1 BAR sensor you can also screw things up.

When you are at 0PSi boost (14.7V ) with a 2 BAR your stock ECU will be seeing 2.5V and think your still sucking Vacuum.

This can lead to issues at regular driving conditions....the ECU will run the car lean.

This can be counteracted by using larger injectors.... but you really need to know what your doing and be able to monitor everything that is going on during tuning.

Hopefully that helps clear up any issues with MAP sensors

[buddha102]

This makes it very very very very very very clear

Thanks

[Big Jeff]

so i will look out for a upgrade map sensor when i turbo my car

[PrecisionBoost]

This makes it very very very very very very clear

Thanks

I just re-read that post and it's confusing.... I was rambling and saying things more than once.... one of these days I will start some threads on technical information such as MAP sensors.

As for upgrading your MAP.... quite often you can insert a 2BAR where a 1BAR was and then use an aftermarket piece of electronics to compensate.

So for example.... you have 4V on a 1Bar that will only be 2V on a 2BAR.... so with a simple amplifier you can take the 2BAR sensor voltage and multiply it by two.

That is to say from Vacuum to Atmospheric the 2BAR sensor will act exactly like a 1BAR sensor with respect to output voltage.

Most will clamp the voltage at a preset value ( such as 4.95V ) and some will allow you to scale the sensor in 500RPM increments.

That way you can decrease fuel or increase fuel by changing the output voltage in the MAP translator.

So you can take the original 2BAR map voltage and put it into an electronic boost controller while the voltage from the MAP translator keeps the ECU happy.

Some translators will even allow you to input your new vs old injectors to help equal out the fuel levels when not under boost.

The more complex you get the closer to a "piggy back" system you get.

In a way even the simple MAP translators can be considered "piggy back" systems since they are modifying the signals going the ECU for the purpose of changing fuel levels going into the engine.

[exist3nce]

Given the ECU doesn't have fuel maps over a few PSI of boost there is absolutely no value in letting the MAP see 7psi

I was not aware the stock ECU has any maps for boost whatsoever. Isn't just designed around a 1bar MAP, never meant to see boost? I know my MAP can't read above 1bar (I've tested it).

[PrecisionBoost]

Well.... that's where things get tricky.... it depends on your barometric pressure on that particular day.

Right now here it is 102.33kPA which is 14.84 PSI

So technically if 1 Bar is 14.7 PSI then my current atmosphere is 0.14 PSI of boost compared to another place that has the standard 101.35 kPA pressure

It's only 100.9kPA in PEI right now.... so that is 14.63 PSI

Since your car has to be able to account for different atmospheric pressures usually it has the capability of measuring and maping a couple of PSI of boost.

That is to say that I'm guessing that they can handle up to something like 110 kPA (15.95 PSI ).... which if your living in PEI right now.... that is about 1.3 PSI of boost above atmospheric.

Hmmm.... that's a wierd cool fact.... I just found out that during some hurricane in the 1960's the barometric pressure dropped down to 13.3PSI !!!

The highest pressure area in earth is somewhere in siberia where it manages as much as 15.98 PSI for the atmospheric barometric pressure

Hopefully you get my point..... the ECU and sensors must be capable of measuring and reacting to pressures that are both lower and higher than your standard 101.35 kPA

[PrecisionBoost]

Keep in mind as well that in most cases the pressure vs voltage is normalized with respect to current atmospheric pressure.

That is to say if your in a 14.0 PSI atmospheric pressure your MAP will read 5.00V when your pressure inside the engine hits 14.0 PSI

Same thing with higher pressure.... if atmospheric is 16PSI then your MAP sensor won't read 5.00V until your engine is at 16PSI.

Some systems can sense barometric pressure before startup and compensate for altitude.

Hopefully you get what I'm saying here..... the MAP can take more than 14.7PSI of pressure because it has to be able to be useable in all conditions... that is to say it must be able to handle something like 16PSI of pressure differential.


Now lastly.... you can under very specific circumstances get pulses of air in your intake tract where the pressure rises above atmospheric..... some race engines are able to manage 110% efficiencies in certain RPM bands thanks to very interesting intake designs.

So.... your ECU needs to be able to account for this.... and this is a case where the MAP pressure differential would be above 100%.... which is to say if your atmospheric is 14.7 then you might get 14.9 inside the intake and have a positive 0.2 PSI boost.

It's not as cut and dry as you might think..... I'm just trying to make a point that there are reasons why the ECU and MAP can take into account slightly higher than average pressure levels.

As for measurement... again... that is based upon pressure differential

Also keep in mind that MAP sensors have some temperature dependancy as well..... most don't have compensation circuitry.... the ECU might use the IAT to compensate... depends on how lazy the engineers are