Overboosting

[sebasteeno]

Sorry for yet another thread but my cars gone from having virtually no boost to being a fecking mad man and boosting its t1ts off and thats with the standard BCS. Im getting 10+psi in 1st and 2nd then the inevitable holding back of overboost and its vitually undriveable. Anyone else experience this or have any clues cos im at the point of throwing in the towel in all honesty.

[Al115]

First... check all the hoses... but you've probably done that already?

[sebasteeno]

First... check all the hoses... but you've probably done that already?

As far as i know they are all ok.

Yesterday we put Smithnesss mbc on it and went mentally fast. Then we put one id bought on and it kept overboosting so went back to standard and now its still overboosting.

[PNuT]

so how tight is the wastegate actuator? when the boost builds up does it shoot up & then drop down & level out?

[sebasteeno]

so how tight is the wastegate actuator? when the boost builds up does it shoot up & then drop down & level out?
The actuator was adjusted to try and get lower end boost. As for the boost if im in fourth and i put my foot down at 2000rpm the boost guage rises to about 8psi by about 3000rpm then overboosts and wont go any faster unless i take my foot off the loud pedal and start accelerating again.

[PNuT]

The actuator was adjusted to try and get lower end boost.

maybe you have just answered your own question

[p fandango]

i'd take the ECU out & reset it as well, it takes upto 75mile before it resets itself & adjust the adaptation parameters

[Yosser]

im at the point of throwing in the towel in all honesty.

I thought you already had....

http://cgi.ebay.co.uk/1998-VOLVO-V70-T5-WHITE-MANUAL_W0QQitemZ180464134060

[sebasteeno]

i'd take the ECU out & reset it as well, it takes upto 75mile before it resets itself & adjust the adaptation parameters

Why?

[p fandango]

Why?
because boost isn't directly measured (it guesses) the ECU won't know if you've changed anything mechanical that it can't detect, so until it gets to feels like changing it'll be running parameters which the ECU thought for the last engine spec. As an example when BT had a split vac hose & loosing boost the ECU compensated so it would run at a decent level, when i replaced the hose i didn't reset the ECU so the boost shot up to 20.8psi because the ECU was still calculating for a leak that wasn't there. So its best to reset the ECU whenever you do any mechanical mods & let the ECU work out the best settings from fresh

[sebasteeno]

because boost isn't directly measured (it guesses) the ECU won't know if you've changed anything mechanical that it can't detect, so until it gets to feels like changing it'll be running parameters which the ECU thought for the last engine spec. As an example when BT had a split vac hose & loosing boost the ECU compensated so it would run at a decent level, when i replaced the hose i didn't reset the ECU so the boost shot up to 20.8psi because the ECU was still calculating for a leak that wasn't there. So its best to reset the ECU whenever you do any mechanical mods & let the ECU work out the best settings from fresh
Thanks for that. Ill do it in morning and keep my fingers crossed it works.

Is it just a case of taking it out then straight back in?

[phil_woods]

Seb

why are you appologising for putting threads up? hope you get the car sorted mate, I was planning on making a clever and useful suggestion but Im thick and havent got a clue

[claymore]

how do you reset the ecu?

[PNuT]

how do you reset the ecu?

remove it

[PNuT]

Thanks for that. Ill do it in morning and keep my fingers crossed it works.

Is it just a case of taking it out then straight back in?

you need to also adjust the wastegate actuator correctly.... what you have done will not do you any favours long term

[sebasteeno]

remove it

Took it out, put it back in, no difference!

[smithy]

Took it out, put it back in, no difference!

leave the battery off overnight it should reset its self after i would say 8hrs

[callyuk]

or just remove the ecu overnight that way you wont loose radio codes ect

[Dangerous Dave]

You could have a leak/malfunction on the standard BCS. If it wasn't working right, it wouldn't allow the pressure to reach the actuator, and overboost as there is no control of the actuator.

[mightywolf]

just check thst you've not wound the actuator arm in too far aswell. someone had done that to mine before i got it and it was overboosting like mad. it fired off the line like a rocket but by the time it hit 4000rpm it started to struggle and then wouldn't go past 5000rpm. If you're looking at the actuator rod from the front of the car it should be pointing straight forward or slightly towards the drivers side. If its pointing towards the passenger side it'll give you the low end power but nothing top end. I reckon its worth checking for the sake of a 15 minute job. I reckon it should be ok if its just slightly pointing towards the passenger side, but if its too much it'll cause problems. Mine is just slighlty pointing towards the drivers side. it starts spooling at 3000rpm, pins you back in your seat at 4000rpm and carries on like that till 6000rpm (redline). Might be worth a check.

[PNuT]

If you're looking at the actuator rod from the front of the car it should be pointing straight forward or slightly towards the drivers side.

it should sit in the same position, its getting the correct opening pressure that is important

[sebasteeno]

it should sit in the same position, its getting the correct opening pressure that is important

Its getting adjusted later

[PNuT]

Its getting adjusted later

here are some static applied pressure values, which as you can see are engine code specific.

Engine Adjustment pressure:

B5204T 12.5 kPa
B5204T2 12.5 kPa
B5204T3 15 kPa
B5204T3 18 kPa
B5204T4 12.5 kPa
B5204T5 12.5 kPa
B5234T 12.5 kPa
B5234T2 30 kPa
B5234T3 30 kPa
B5234T4 12.5 kPa
B5234T4 R-line 28 kPa
B5234T5 12.5 kPa
B5234T6 30 kPa
B5234T7 12.5 kPa
B5234T8 30 kPa
B5244T2 30 kPa
B5244T3 12.5 kPa
B5254T 12.5 kPa

yours should be the one in bold

[Dangerous Dave]

30 kpa is 4.35psi