Changing the 250KPA whit 300KPA

[marius_s4]

Changing the 250kpa mapsensor whit 300kpa whit no remap of the ecu it must be a problem ????i have stage 1 remap 286 hp program inside AAN engine

[VladaS2]

Is that a question or a constantation ?

[marius_s4]

a question, i change'it and the engine goes well but in time it coud be some problem?

[VladaS2]

Well I am no expert but will give my view anyways and stand to be corrected. I think it depends if the reading from MAP sensor are absolute or relative. If they are absolute then you have nothing to worry about. If it is relative, the new peak boost level which in your case is at probably around 1.3 bar will convert to 85% of sensor max (2.5 bar). When you put 3 bar one you will get only 65% full. So ECU could probably give 20% fuel less. Which means you will run leaner. Once again this is a laymen opinion. I am interested in real answer too. Cheers

[porkkis]

It doesn't affect fuel delivery.
It does mix up the boost control a bit. Bad idea.

[1975DCS]

From what I have learned al Bosch mapsensors work from 1-5 Volt. So if you have a 3 bar mapsensor (2 bar boost that is) max boost will be 5 Volt (I think it works this way). For a 2 bar mapsensor (1 bar boost that is) max boost will also be 5 Volt.

So now your ecu will read different Voltages (because of the different mapsensor) and therefore is reading false information and supplying the wrong ignition data and injector duty cycles...

I have the same sort of problem: my 3B is live (road) mapped (based on a basic chip) but is only using a 2 bar (200KPA that is) mapsensor. This limits the boost to sligtly over 1 bar, while the ABY can do much more with the 2.5 bar mapsensor.

It is a shame to drop my chip in the bin, because the previous owner has done this recently. And altough it would probably easy to convert the chip data from ? Volt to ? Volt for a chip writer. It would be of no use because I still would be running the same boost levels, to get that sorted I would need a new midrange remap. Just as much work as finding a different chip then...

[Mihnea]

God, the S2's motronic DOES NOT USE the MAP sensor for fuel or timing, period. I thought Porkkis had made this clear enough.

If your S2 is road mapped but only on a stock MAP sensor, it shouldn't matter, the ECU can also be mapped above 1 bar with the stock MAP sensor but it's not very pretty.

Just changing the MAP sensor for a different one without a new chip made for the new MAP sensor at least sounds a little bit suicidal for me.

Mihnea

[VladaS2]

Minhea can you explain why is it little bit suicidal?

[Mihnea]

if the chip is programmed to run 1.5 Bar (=5v) on a 250kPa map sensor and you change the sensor to a 300kPa, the ECU will try to reach what's programmed in the chip, 5v. 5v on a 300 kPa is 2 Bar. Do your own homework but some turbos might not get to 2 bar reliably, engines might detonate at 2 Bar, and so on.

[1975DCS]

Sorry, this was kind of what I ment...

[marius_s4]

Yes the chip is programmed to run 1.5 Bar and now run 1,7 bar bat no detonation, the problem i think will be the k24 turbo