Faulty MAP Sensor

[scottish-sr]

It seems that the MAP sensor maybe causing the over fueling issue with my car which in turn causes a misfire.

Basically the engine will hold boost fine right to the red line, but then once the gear is changed, will start misfiring.

The garage have tested the MAP and say that once it get's to 0.8bar the voltage goes crazy and lots of fuel ends up getting dumped into the engine.

On VEMS the current readings are

MAP Sensor range : 400kpa
MAP Offset Setting : 4.75
MAP Sensor offset (kpa) : 5
MAP Range Unit : Normal <510kpa sensor
Table kpa unit : 2 > 250kpa

Running VEMS 3.3

While the engine is off the MAP sensor is reading 101kpa
Engine is an SR20DET which should be running 1.4bar boost.
What replacement MAP sensor should I be ordering and is there anything else I should be looking for.

[mattias]

First : Always, always mount the ECU with the connectors and MAP sensor nipple pointing down.

It's in the webshop, https://shop.vems.hu/catalog/bare-sensor-p-141.html

The correct range is 414 kPa (see "F1 for help" in that dialog for recommendations).

[scottish-sr]

The ECU is mounted in the glovebox in pretty much the position it's in in this picture

https://shop.vems.hu/catalog/vems-pi-48.html?osCsid=8e5d0ae9b5cc1660e2fb0e81ff01cd44

So I should get it re-mounted then. Can you explain why this is and what difference it would make?

[mattias]

Moisture, condensation. Check any stock ECU with MAP sensor, there is always an intricate thought behind the hose that goes from the engine to the MAP sensor. Usually a "filter" is involved.

[scottish-sr]

Thanks for the reply. I will get the ECU remounted so it sits the way you described.

[scottish-sr]

Just to confirm, should I change my MAP Sensor range from the current 400kpa to 414kpa, then adjust the MAP Offset setting to show 101kpa with the engine off.

The reason I ask is the ECU was bought with a working MAP on it and this was the settings on it when I received it. The ECU was mapped by Gunni, the VEMS help says "Calibrations in general should be done BEFORE engine tuning. Changing calibration values afterwards usually have negative effect"

Here is a screengrab of the ECU calibration settings.

[gunni]

You should.

[scottish-sr]

You should.

Will this not disrupt the rest of the mapping that you done Gunni as it states in the Vems help guide?

[gunni]

Yes, you will need to log and review the fuelling, the change of MAP reading will be minimal so it´s not going to screw you over.

[scottish-sr]

Thanks Gunni. It's overfueling on WOT and full boost so this may help solve it.
It's Alex Hannam (Docwra) old engine and ECU btw.

[gunni]

I figured, that combo ran really well on the GT30, I was impressed with it.

[scottish-sr]

It's running a GT2871r at 1.4bar now. That's how I got the engine from Alex.

[gunni]

Ah thats what it was, i forget. To many projects everywhere.