overboost

[mike 850]

hi, need some help with the ecu on my 95 850 t5, i recently fitted a mbc and gauge and have been running it a .8 bar boost, i did a diag check and it came up with 4-1-4 which says in haynes too much boost, is this because ive taken the control away for the ecu or is it at a dangerous level,
many thanks
mike

[volvotuning]

It's because you've taken away control from the ECU and is seeing too much air flow compared with what is acceptable in the stock map settings.

Adam.

[mike 850]

ok, tbh im planned getting it ricad but i just wanted a bit more power in the short run coz i canna afford it yet, do you rekon its safe to run or turn it down a bit? thanks for help
mike

[volvotuning]

As long as you don't over-do it then it's safe. But you'll always have the fault code.

Adam.

[mike 850]

cool, thanks alot bud, like i said hopefully wont be for too long coz i wanna get the chip done, think ill turn i to around .7 or something and stop being so impatient :slap:

[Paul ABZ]

B5234T/B5204T/B5234T5:
Initial boost pressure: 130 – 140 kPa (absolute pressure) at 3000 rpm and +20 °C. Maximum boost pressure: 159 – 173 kPa (absolute pressure) at 5100 rpm and +20 °C. Boost pressure given as an absolute pressure. Absolute pressure= Atmospheric pressure+Gauge pressure.

Manually setting the boost pressure higher than these figures will give you the code you are getting.

[mike 850]

just to update, i've turned it down to around .7bar and it doesnt come up with the fault anymore and actually feels smoother, im guessing thats coz its in the ecu range? ideal

[volvotuning]

Yup! But you'll probably find that when it gets colder and the air is denser you may still get the overboost occasionally. At least you can see how it works!

Adam.