[Mk2] [Turbo] no dump valve!!!!!

[hnygt4]

hi, I need some help. a little while ago my bov stopped working, which i thought was the bov its self. but I have now tried a ssqv and a stock mr2 valve and neither work. prior to this i hadnt touched any of the vac lines or anything it just stopped working.
I have also tried running new vac lines and from different locations, aircon idle up, map sensor and (i think) power steering vac line.
nothing has worked apart from when i rebuilt my blitz valve, cleaned and oiled it, it worked about 4 times and stopped again.
any suggestions why this is happening?????
the valve is getting vac and boost so i dont see why this is happening, please help!!!!!
everything else seems fine, boost gauge shows normal vac and boost, so i'm pretty sure theres no leaks.
the actual vac tubing is new aswell.
any ideas???? im sure the compressor surge isnt good for the lil ceramic turbo
cheers
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[Martin F]

try taking a vac line from the inlet manifold, i can't think of anything else why 3 different dump valves should stop working apart from contamination from a damaged turbo but even then they should work temporarily

has to be something to do with the vacum, where are the d/v's conected to the system?

[hnygt4]

I have a carlos sainz chargecooler and a t-piece between the turbo and the cc, my normal vac source is off the aircon idle up line(which i believe is the standard location for a mr2)
it has a good boost supply to it

the vac is nice and strong
the only things that i can think of i have tried:
checked its getting boost to the valve
different valves
different vac sources
different vac lines

pretty sure theres no vac or boost leaks.
I didnt fiddle with anything before it stopped working
turbo boosts as normal

any ideas greatly appreciated!!!!!

[mattcambs]

This is a bit of a long shot, but there aren;t any one way valves in the DV vacuum line? I only say this because some pleb put one on my car before I bought it and the seller (innocently, I think) described the DV as a flutter valve! Er, that would be turbo stall then!

The way to check you have a vacuum is to take the line off the DV with the engine on - the idle revs shouls drop briefly before the ECU catches them. Then hold the line with your thumb just hovering over the end. Rev the engine (via the throttle butterfly) - when you let off the throttle your thumb should be sucked quite strongly onto the end of the pipe.

If you have a good vacuum, then it's simply the case that the DVs were all faulty. I tried 2 DVs thinking my vacuum was poor - both were faulty, though!

You'll sort it, don't worry How about borrowing a known working DV off someone? You don;t need to connect it to the intake pipe to see if the piston moves in or not.

[hnygt4]

no 1 way valves, just blue vac line, the other line i tried was clear. one of the valves i tried was an ancient hks sqv, dont know if it worked, the mr2 valve was working when it was removed. i have taked my blitz one apart twice, cleaned the insides out and oiled it up, piston moves freely enough. even connected it to my compressor and it openes fine, did this once with the vac line connected, rev'd the engine and sprayed air and it blew the valve off the compressor line lol. the vac is nice and strong, and yes the revs change if i move my finger off the end of it. I am going to try a valve off a mates car that i can see working just before putting it on mine but cant see it working.

all it needs is boost and vacuum??? it has both but wont work!?!?!?!

[hnygt4]

still no success getting it to work, tonight i unplugged the afm so it wouldnt care if i pulled the bov off. while revving the engine the piston in the bov got harder to move by hand and on lift off it got alot easier to push open. now is the vacuum suposed to pull the valve open or does the boost push it aswell???

also while revving, air blew out of the hole the bov goes into, the sound is just like the blitz bov!!!

tried revving it with the bov in place and all i got was the lovely flutter sound.

i have redone all the boost lines(intercooler), checked and double checked the clamps.

if the vac is supposed to do all the opening of the bov then i have a weak vac source, from all the vac lines i can find to use!?!?!?!

any more ideas would be awesome!!!!!
cheers
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[Steve-O 2007]

hhmm, you dont want air leaking out of where the bov goes while revving, try and get it on so it doesnt leak, could be your problem

[hnygt4]

sorry i meant with the valve out of the intake system, so i could get to the piston. ( if you disconnect the afm then it doesnt bog and die on idle or while revving with a massive boost/vac leak, mine ran ok with the whole intercooler in the garage lol) i still had the vac line connected to the valve so i could see what effect it had on the pistons movement.

still no luck, any ideas???