prob a stupid question

[stevieITR]

wen car is idleing and you put your hand over dump valve should it be sucking in air?

ill prob get slated for asking this but i just thought i would. can some1 explain just how a dump valve actually does its job please? i know it releases the pressure wen you close the throttle.

 

[B6lee]

wen car is idleing and you put your hand over dump valve should it be sucking in air?

ill prob get slated for asking this but i just thought i would. can some1 explain just how a dump valve actually does its job please? i know it releases the pressure wen you close the throttle.

No it shouldn't, what dump valve is it ??

 

[fq-craigus]

from my basic understanding all it does it release the un used boost pressure when throttle closed, but like lee says it shouldnt have any vaccume at all. i would better reccomend a recirc valve imo, you get a dump at lower revs and a chatter at higher chatt

 

[fq-craigus]

kinder to the turbo too

 

[Steve220]

You need a stronger spring. What type of BOV is it?

All BOV's will have a sensor line connected to them which in turn connects to the inlet manifold post throttle body. When the engine goes on boost, the sensor line receives +ve pressure and pushes (with help from the spring) the piston/diaphragm closed, which seals the system and stops air leaking out the BOV on boost.

When you come off the throttle, the inlet manifold goes into vacuum and subsequently the sensor line does, but the boost hoses pre throttle body remain a higher pressure which pushes and pulls the piston/diaphragm open and lets the excess boost out simplsh!

 

[gooner8]

i thought it was kinder to the engine? And the one's that dump are better for the turbo? Plus it should be shut when at idle. Only open when letting the unwanted pressure out! Maybe wrong?

 

[fq-craigus]

You need a stronger spring. What type of BOV is it?

All BOV's will have a sensor line connected to them which in turn connects to the inlet manifold post throttle body. When the engine goes on boost, the sensor line receives +ve pressure and pushes (with help from the spring) the piston/diaphragm closed, which seals the system and stops air leaking out the BOV on boost.

When you come off the throttle, the inlet manifold goes into vacuum and subsequently the sensor line does, but the boost hoses pre throttle body remain a higher pressure which pushes and pulls the piston/diaphragm open and lets the excess boost out simplsh!

ahh yes! thats what i meant, i knew someone would understand me lolz

simples

 

[stevieITR]

ah bullseye i may have found my problem then with only revving to 2k, im unsure of the make ill see if i have a pic of my engine on my works comp here and post it up

 

[stevieITR]

ok found 1 but you can just make out the dump valve

 

[gooner8]

Look's loud with that thumpet lol not a blitz or hks. maybe a turbo smart one? Of what i can see.

 

[stevieITR]

em yes you could say it is rather loud lol,

would i be right in saying that if the dump valve is passing it will be acting like a boost leek??

 

[stevieITR]

and im asuming if there is air getting in throught the dump valve then the ecu will think there is a prob and puting engine in limp mode becuase the readings from the maf sensor will not be picking up the excess air flow? or have i got it totally wrong?

 

[fq-craigus]

and im asuming if there is air getting in throught the dump valve then the ecu will think there is a prob and puting engine in limp mode becuase the readings from the maf sensor will not be picking up the excess air flow? or have i got it totally wrong?

your right on the theory that it would be like having a boost leak, not sure about the limp mode bit, try taking the dump valve off and blocking the pipes off with bungs reset the ecu and see if that helps if it does invest in a new dump or recirc valve if not back to the drawing board

 

[stevieITR]

ok nice 1 i shall do this wen i get home from work since the evo is left at the house lol,

im asuming i have only to rev to just past maybe 2.5k just to prove it is getting past the 2k mark?? since i would have no dump valve on i dont really wanna be spooling up the turbo do i?

 

[fq-craigus]

ok nice 1 i shall do this wen i get home from work since the evo is left at the house lol,

im asuming i have only to rev to just past maybe 2.5k just to prove it is getting past the 2k mark?? since i would have no dump valve on i dont really wanna be spooling up the turbo do i?

long term it can depleat the life of a turbo but some people run none at all with no problems, it will help discover if its the bov that is the problem, the easiest thing would be to change the spring if you have the others if not the bungs will do the job to problem seek.

the boost will still be controlled its not like removing the pipe off your j pipe where the boost is unlimited and can cause your turbo to overboost

if it is the bov and after you reset the ecu your car is fine a new bov will usually come will varied springs depending on the boost you are running

 

[stevieITR]

i removed the dump valve and reset ecu, first couple of revs and it only went to 2k again but then it revved freely, every now and then it will still only rev to 2k and then will rev freely again, sometimes hesitates.

took the evo a drive tho and went good, bit jumpy tho wen puting the foot on the gas. stopped for a rounabout, only revved to 2k then stalled, started first time and then drove good after that,

It kinda looks like there is something sticking, maybe throttle position sensor? im pretty sure its not a boost problem cause the turbo is spooling up etc and the car fair shifts lol.

anyway im thinkin tps or maf sensor. im really not sure. if i called out the AA would they be able to confirm the prob for me??

 

[RsvRob]

They would only be able to do a diagnostic check as you have already done. Altho there kit won't register anything lol

Have you checked the throttle body? Taken it off and cleaned it....
Have you checked the MAF? Taken it off and cleaned it....

Use carb cleaner for both

Have you had evoscan plugged in to check the tps sensor to see if it is registering that it is fully opening?

Also if the problem is now intermitent after you have removed the BOV, then it will be an airflow problem somewhere.
Can you check the AFR on idle?

 

[RsvRob]

and im asuming if there is air getting in throught the dump valve then the ecu will think there is a prob and puting engine in limp mode becuase the readings from the maf sensor will not be picking up the excess air flow? or have i got it totally wrong?

Correct ....

You are getting to much air in the system after the MAF has registered it. So when the o2 sensor registers your afr on exhaust side, the ecu picks it up as far to lean and goes into limp mode

 

[stevieITR]

ok how do i check the AFR and were is it lol

i have a tin on electrical contact cleaner would that do the job?

i have cleaned the MAF sensor, and i will go have a look at the throttle body in minute once it has cooled down a bit