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Techie Help - Cold air intakes


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Posted

The 3 bar MAP sensor (manifold absolute pressure) is used to determine the absolute pressure (not the relative to atmospheric pressure) of the air inside the intake manifold and the atmosphere (barometric pressure).

This information is used to determine the density of the air entering the combustion chamber , which is used when calculating the proper air/fuel mixture for the engine.

To simplify.

By running a VTA valve your confusing the ECU by dumping the measured intake air.

The MAF measures the air being drawn into the induction/turbo/manifold.

When you shut the throttle and dump the air to atmosphere the ECU thinks the air is still in the induction side and adds fuel to match.

But the air has been dumped, not recirculated like it should in standard form.

Fuel is injected and there is less air in the system than the ECU thinks.This is over fueling..bore wash...big bang, etc!!!=bad new

Thats a real rough way of explaining it, I could go indepth if you likeface-icon-small-smile.gif

Posted

Problem is it was fitted before the remap and is still on now. I like the sound too much. Does this mean that my car will be overfueling just now.

If so i will have to get one of these 3 bar MAP sensors. Never heard of them before but thats not suprising as i didnt even know

where the turbo was when i first bought the car face-icon-small-smile.gif

Am sure there is a lot of people with a VTA without anything like this fitted.

Posted

I had the turbosmart vta on mine..........................binned it not that long ago and put the original back on!!!

The reason............my oil was stinking of petrol and my oil temp went through the roof one day for no reason, now whether that was a result of the vta i dont know. Conflabbed with the Oracle (squirrel) and came to the conclusion that the petrol could have degraded my oil hence making it thin alot.

This is not set in concrete as the reason but it is the only possible one we could come up as my car is treated with kid gloves. Since changing the vta and my oil i have had no problems whatsoever, ok so i have lost the nice loud pop bang on gear changes but my engine means alot more to me than pops and bangs.

Take from this what you will but i know what i am doing from now on and anyway my induction noise is better than any vta i have had.

Posted

Question and Answer time

Q) Over fueling just now??

A) Yes

Q) Will I need to fit a 3 bar map sensor?

A) No, just re fit the Std one and enjoy

Q) Am sure there is a lot of people with a VTA without anything like this fitted.

A) This is why there are so many people that complain about Subarus blowing up and they cant understand why.

Moral of the story is, dont fix whats not broken and dont ask max power garages for adviceface-icon-small-smile.gif

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