beezor

iTrader: (1)

Hi,underneath the throttle body on my bug sti there is a pipe which comes from the manifold-it looks like it should have a vac pipe attached as its sucking in air but i've checked all the pipework and everything seems to be intact and in place,could anybody please shed any light on what should be attached,many thanks.

merlin24

iTrader: (1)

Is it on the throttle body or directly below it ?
IIRC,on the throttle body there are only 2 coolant hoses - no vac connections.
Below the throttle body at the back of the manifold, you have the pcv valve on the manifold which connects to the intake duct/breather on the crankcase.
Bottom of the manifold and behind the alternator you will have the Purge control solenoid valve which has 2 vac pipes.

Mick

beezor

iTrader: (1)

Thanks for that,yes it's on the manifold directly below the throttle body,just need to work out where the pipe is that should be connected to it.

beezor

iTrader: (1)

Would anybody know if it is the pcv valve thats come off would this cause the car to run rich off boost & lean on boost at all as it's definitely sucking in air?

propofol

There should be a valve on the PCV inlet to intake manifold - ?? may limit the vacuum leak.
A vacuum leak on a MAF engine will cause a lean condition (unmetered air entering the engine). This should be countered by a rich command from the O2 sensor (giving rise to positive fuel trim numbers, thereby bringing the mixture in the cylinder back towards stoichiometric). This lean condition will become less pronounced as the revs rise and manifold pressure becomes less negative (and therefore less of a vacuum leak). When on boost and manifold pressure > atmospheric pressure you may lose air out of the PCV valve (this probably shouldn't happen as it is a one way valve) then you will have a rich condition. This is the opposite to what you have asked!

beezor

iTrader: (1)

Cheers the car is running mafless as it's running an alcatek,something is definitely amiss as you can hear the air being sucked in through the pipe(i think something is disconnected),my wideband is showing running rich under normal driving but very lean at wot-i thought it was the adjustable fpr failing(replaced the diaphragm though) but I'm sure this is the cause.

beezor

iTrader: (1)

Right it would appear that the pipe would have a hose attached to it running to the recirc valve,however mine has been blanked off so in theory this pipe would be blanked off as well but when I did this the car won't idle properly and wants to stall all the time,I'm at an absolute loss now.

360ste

iTrader: (1)

Get a picture up as it will give a better idea. The one I am thinking of is connected into the breather pipes. So if I can see it I will know which one you are on about and can take a picture of how mine is connected for you to see.

beezor

iTrader: (1)

I'll take a pic of it tomorrow mate,I think the one you are on about is on the right hand side of the manifold under the throttle body if you were looking at it from the bulkhead,this I believe is for the pcv valve but on mine it has been blanked off as I'm running a catch can,it's the one on the other side.

merlin24

iTrader: (1)

As in #2, PCV valve connects to this hose





Mick

beezor

iTrader: (1)

Thats the pipe-just dont know if it was blanked off or whether it had a breather or vac pipe attached-cant find any missing pipes whatsoever though!

beezor

iTrader: (1)

A mate of mine who breaks scoob's had a 2002 bug sti prodrive in his workshop today so i took the opportunity to have a look where the pipe goes on that car & it goes to the re-circ valve so for the life of me i cant understand why it cant be blanked off without the car running like a bag of poo as i run dv delete!

beezor

iTrader: (1)

Well my mapper had a look at my car sat morn & although we couldn't fathom why the car ran like a bag of poo when the pipe was blanked off we did that anyway then altered the map,once done we went for a drive to see how it was running & it was still the same-rich off boost & lean on boost,having already changed the diaphram in the fpr & changed the paper element in the sytec fuel filter we decided to check the rcm 340 fuel pump & this is what we discovered...

The sock had come apart(can only think this is down to methanol) & had sucked itself into the pump! Anyway put a new sock on,one last tweak to the map & the car is now running like a dream-hoorah!