Variance in atmopheric pressure

[Patrick]

I am just wondering what sort of variance should you be getting with the map sensor at atmospheric.

I am running bosch STYLE 3 bar map sensor,  i get any where from 99kpa - 108kpa, it drifts around a bit i think engine bay temperature has an effect on this.  I understand the BAP has an effect on this but its usually just +1kpa in most cases.  Also each time i check it's in my garage so sea level should have no effect on the variance.  As I'm getting my car back on the dyno in a few weeks i thought it might be a good idea to get a genuine bosch sensor unless it is actually normal for the sensor to drift around this much.

Cheers

Pat

[Simon]

You will see some movement based on the weather, If there is a high pressure system then the baro / map will be up and a low pressure day will give low readings.

The main thing is the MGP reading with engine not running should be 0.

[Patrick]

I double checked and there's a fair bit of variance, MGP is any where between -8 to +8 when cold/hot.  At operating temperature it sits close to 0 with engine off (+/-3).

[Patrick]

sorry forgot to mention units is in kpa

[Simon]

That's not so good as that difference will have an effect on the tune. Check the power and grounds for the sensor.

As if theses are suspect it will cause the readings to change.