overboost whats the cause

A

allyrs

Guest
ok.
ive only owned my r for a week.
when i put my foot down the turbo spools in and the boost increases as you would imagine.
instead of stopping at .7 or a bar as you would imagine, it keeps going. my first and only time doing this the car exhaust popped/backfired and i lost power (i felt underfueling as the boost gauge went above 1.5 bar). i thought actuator or boost leak or wastegate.
now my plumbed in guage which runs from intercooler to inlet sits on 0 bar all the time untill acceleration where it will rise. it never reads negative vacume pressure but the standard guage does. i tested my other guage and it works fine. I suspected vacume lines so took off all pipes. they were perished but i could not see obvious splits. the intercooler looks in good nick. the car has no boost controller.
further from this i has put another boost guage accross the actuator and it only just goes into positive pressure on acceleration. i also put my compressor on the actuator while its on the car and put it up to 80psi and it never bled it off! the dumpvalve doesnt go off but there is vacum pressure at it- though this is the only hose ive not full checked as its so hard to get right onto its origin nipple.
any ideas guys?
ive orderd new samco all round and a new actuator but the parts arnt here yet. if the turbos comming off then i might as well uprate it?
this cars a bloody curse- should have stuck to my evos

one week and this has happened-
overboosting,
pass window wont go up from driver side now,
some kids left bricks on the road-cracked bumper missing tow eye cover, smashed headlight and indicator,
new ordered headlight arrives smashed,
ordered samco forgotten to be sent,
flat tyre today- turns out to be inside wheel corrossion
and another one for today, fuel flap wouldnt open for 20mins had to use screw driver and push on the other side.
im feeling quite down. i really cant be arsed to take the turbo off as i have a feeling ill snap a few bolts in the head bend a few oil pipes and get trapped under the car in the process:frusty:
 

John

New Member
Well atleast it cant get much worse!

Did you not spot these issues when you test drove the car before buying it?
 
A

allyrs

Guest
it seemed fine when i test drove it and the guy was great. when i opened it up on the road it was fine but i never took the revs high enough for the backfire. the guy even put a new mot on at as he was so confident nothing was wrong. the guy had a serious knee problem and couldnt press the clutch. genuine sale. its sat about a while as the guy was waiting for his knee to get better but now he needs surgery so the car got sold. all the other problems developed in a week lol.
 
A

allyrs

Guest
there is no boost controller. standard boost solenoid is there and has no drill hole in it. the 1bar loop has not been done and the actuator looks standard.:?

boost is controlled through so many things though! i know the boost is uncontrolled lol. its wht is causing it is what i want to know. pressure is produced through the turbo it is maintained by its enviroment ie the vacume hoses, intercooler, inlet etc and is released by wastegate, dumpvalve, combustion or change to enviroment ie boost leak.
 
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A

allyrs

Guest
but if it fails surely the actuator will still bleed off at its preset safety level? prob around a bar?
the set up looks pretty standard. its 292 on the rollers. exhaust filter dumpvalve
 
O

owens

Guest
if your running no vaccum it seems like you have a hose dissconnected, as this read as 0 bar (normal air pressure) and inturn would cause overboost, have you checked the vac pipe on the intercooler, mine has come off before and caused mass overboost and its easily missed when the intercooler is removed and re-fitted
 

youngsyp

New Member
First off, you need to sort your plumbing out.
Don't worry too much about your boost gauge not reading vacuum, that's because of where you have it plumbed in. I'd recommend you plum it into the same line that the stock gauge uses, the line that goes to the passenger front wheel arch, into a little plastic box (MAP sensor).
Whilst you're doing that, check the rest of your vacuum lines against the diagram floating around the forum (do a search). As has been said above, it would seem you may have no vacuum pipe to your actuator.
If the vac pipes are all as they should be, it could be your actuator that is seized so, the wastegate isn't opening, to release exhaust gas, and control the boost level produced.
You can check this by moving the actuator rod with your fingers. From what you have done already, this would seem a likely culprit.
If the actuator doesn't see a change in vaccum/positive pressure, it can't 'bleed' off boost. It needs this pressure to move the actuator rod, to open the wastegate.

I think you can check the boost solenoid by splashing 12 volts across it ?! You should hear it activate. You could also remove the pipes from it and connect them together, to see if the actuator is working.

As for the BOV not working, again, it either doesn't see vacuum or, it's seized or, it's adjusted too tight, if it's adjustable.
It sounds to me that there is an issue with your vacuum circuit !

Paul
 
people get confused with a pulsar plenum chamber, remember yu wont get negitive vaccum unless you take the reading from passed the throttle bodys!
 
A

allyrs

Guest
right ive got the car in pieces again ready for the new samco 2moro all the right pipes were connected. the only one i cant get to is the one from dumpvalve to the back of the plenum. how do i get to it? i cant get my hand behind it.

what could you expect happening if the boost solendoid was broken?

all the pipes were on the intercooler by the way i still cant see any splits.
i saw one little nick in a hose comming off the end of what looks like a regulator at the far right side of the fuel rail? there are two thivk black pipes going to a brass cannester and then one smaller black pipe behind it. ill try and get a pic:
http://www.bebo.com/PhotoAlbumBig.jsp?MemberId=462669361&PhotoAlbumId=1091307111&PhotoId=6906178275
ithink it goes to a t piece that links to this:
http://www.bebo.com/PhotoAlbumBig.jsp?PageNbr=1&MemberId=462669361&PhotoAlbumId=1091307111&PhotoId=6906178428

i can barely get my hand down to the actuator but i have had success and got the arm to move today so i can rule out the waste gate and actuator!
i was being silly when i tested it last time lol

cheers guys
 
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A

allyrs

Guest
Ive re routed the vacum line from the plenum to the actuator missing out the pipe that runs under the intercooler and missing out the boost control solenoid.
the car now boosts to 0.5 bar wooo:-D
i know the standard boost is .7 so the solenoid makes up the rest?

im just about to wire in a boost controller accross my new line so i can have my boost about .9bar. its just a manual dual setting one. anything to consider regarding the boost controller, my lack of solenoide and my set up?

is this a common problem? does my overboosting sound like a reasonable explaination for is the solenoid failing.
i imagine it doesnt allow the boost to pass to the actuator and just keeps building the boost?
cheers for the support over this difficult week lol:lol:
 

MarkTurbo

Well-Known Member
allyrs said:
i imagine it doesnt allow the boost to pass to the actuator and just keeps building the boost?
The solenoid connects to a T piece in the actuator-plenum pipe, all its there for is to bleed off a small amount of air to get the extra 0.2 bar. It would have to be seriously f**ked to make the car overboost ;-) You sure there was no leaks anywhere?
 
A

allyrs

Guest
yea im pretty sure its the solenoid. with it out of the way the car boosts to .5 bar. with it in the system the car boost off the scale.
 
A

allyrs

Guest
no, i looked for that as i had heard people did that to increase boost.:?
 
G

gtirbhp

Guest
did you say 292bhp on the rollers?

if not sorry but if im reading correctly then the turbo wont be stopping at 0.7bar in the first place...More like 1.0bar to me..
 
A

allyrs

Guest
im going to have to put it into a garage. because im just not happy with it. 292 is what the rr print out shows. but who knows what boost that was at? doesnt say on the sheet but theres no boost controller? i called the garage who did it and they think its .7bar with filter exhaust fuel pump and dump valve. its going to them in a week to have a look at.
 
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