adjusting map sensor for boost????

[JC]

hey ppl, i've turboed my car and the map sensor keeps reading boost does anyone have a suggestion on how to keep the map sensor from reading boost??? any device to fool the map sensor?????

[ubuyau]

On a stock computer, the only way i know would be to get it chipped and a new map sensor.

The alternative we're using is check valves on the MAP vacuum line. In the photo below, you'll see the line off the throttle body for the MAP sensor has some little plastic check valves to relieve the hose of any positive pressure. That way you wont throw a CEL, but make sure you have something to take care of the extra fuel required for running forced induction.


--Tim

[tango]

Honestly, you are better off finding a 3-bar MAP sensor than to use checkvalves. It's only a matter of time until one (or all, in my case) fails. When that happens you will lose the 1-bar. I have heard of specially made check-valves designed for automotive use (as opposed to other uses that have been used as a stop-gap measure) but I've never tried them. Let me remind you (or tell you, if you've never heard) it is IMPOSSIBLE to build a reliable turbo-system on a budget. It's either you spend now and get it right or spend more later to repair the damage.

[debo890]

how would you setup the 3 bar map to work with the woo computer?

[Efratech]

how would you setup the 3 bar map to work with the woo computer?

i was asking my self that same question.

[DomWoo]

the only way i would see a 3 bar working with our daewoo is to have a piggy back unit such as the Greddy Emanage and stop the sensor reading at no boost and no vacumm

[JC]

i was thinking about the same thing our computers wont adjust with the 3 bar map sensor, the ecu wasn't programmed to read boost so the ecu will freak out,
thanks for the suggestions

[GsiTurbo]

For a good one-way check valve, use the one that installed on factory vacuum line going from the intake manifold to the brake booster. 3 Bar MAP will not be recognised by the computer. Also, we can supply voltage clamp for the MAP- this will allow MAP to read normally untill adjustable level...above that level all voltage is cancelled and ECM will never see that - this must be used together with one-way valve, or damage to the MAP sensor will occur.

Tom

[JC]

if you experienced this and your advise works let me know what i need to do to make this theory work

[PrecisionBoost]

Also, we can supply voltage clamp for the MAP-

I guess this means you want precision boost (me) to get off my ass and design that map clamp you asked for last year

But I'm lazy!!!

It will cost 1 million dollars ( holding pinky to side of mouth )

I guess I have to make one for my car anyways..... perhaps you should set up some kind of group buy to see how many I should make in the first batch.

I guess a poll should be done to see how "fancy" it should be.

If the components are mounted in epoxy it will be ugly but cheap.

If I have to design a nice box for it.... the cost will go up by $5 to $20

So.... nice box and a few bucks more or simple, cheap and ugly?

[DomWoo]

seeing how i dont need it because the emanage does it for me... but my thought has always been.. cheap and ugly then if yo uwant it pretty get your own box and put itn in it later.. but thats just my 2 cents for whatever they are worth..

[tango]

3 Bar MAP will not be recognised by the computer

When I was doing my project I came across a 3-bar that was designed to work with aftermarket applications. Not sure of the specs now but I'm sure I saw it.

[JC]

so with the voltage clamp you can keep the stock map snsr or do you still need a 2-3 bar map sensor?

[PrecisionBoost]

With a map clamp you use the stock sensor.... which is nice because it keeps the factory maps for "less than boost" driving.

I suppose I could also make you guys a map sensor translator.

So.... you could have a 3bar map sensor.... and my little circuit would translate the voltage from the 3bar sensor nto the voltage the ECU would expect.

So.... for example...

The stock 1 bar sensor might output might be 4.6 Volts at 0psi ( 14.7 atmospheric) which is as high as the ECU would expect to see (since it's for a naturally aspirated vehicle )

Now.... if you throw in a 3 bar sensor the ouput voltage would probably be something more like 1.5 Volts at 0 psi.

So.... if you simply replace your 1bar with a 3 bar the ECU won't work correctly since it will see 1/3 of the amount of voltage.

What I could do is design a circuit which would amplify the 1.5 volts by a factor of three all the way up to 0psi and then act as a clamp.

This way the ECU would get the correct sensor voltage for anything under 0psi and it would clamp the voltage at 4.6V when boost is applied.

1 bar sensor 3 bar sensor 3bar with translator
1.0 V 0.33V 1.0V
2.0 V 0.66 V 2.0V
3.0 V 1.00 V 3.0V
4.0 V 1.33V 4.0V
4.5 V 1.5 V 4.5V ( 0 PSI = 14.7 psi = 1 bar )
4.7 V 1.57V 4.5V ( 1psi boost )
4.8 V 1.60V 4.5V (2 psi boost )

So if you had the stock 1bar MAP sensor and your at 2psi of boost the ECU would think the MAP Sensor is damaged and go into safe mode.

If you had a 3bar the ECU would be fine but it would dump in only a tiny bit of fuel because it thinks it's looking at the 1bar sensor.

If you had a 3bar with translator it would put out the exact same signal votage at the 1bar all the way up to 0psi and clamp the voltage at 4.5V to ensure that the ECU is happy.

Having said that.... there would be two outputs.... one with the "translated voltage" for the ECU and one for all your aftermarket accessories such as boost gauges.

This way your ECU is happy, you can keep the stock fuel and ignition maps and you can use aftermarket parts to change the fuel and or ignition maps when boost starts to show up.

I suppose I could also design the translator to work with larger injectors.... so that the 3bar MAP, translator and larger injectors work together to give you the correct level of injector pulse width (which controls how much fuel goes into the system )

Hmmm..... I keep on thinking of new add on features..... I suppose it might be better to make some "simple" things such as a cheap adjustable MAP clamp and then make more expensive units with more features such as the translator circuit.

[JC]

thats good that you mentioned the map clamp to work with bigger injectors thats essential when it comes to fine tuning, i would definetly want that feature even if its a couple bucks more. keep me informed.