Tial 50mm bov on m20 doesn't blow off

[Kozworth]

Got it in good condition but used. It is right behind the drivers high beam, with the vac line going to the purge valve port on the tb. I do not see it open or hear it.

Any ideas? Is it possible that its a mechanical failure? I had it also run off of the booster lines but still didn't work.

If it helps, I cannot compress the diaphragm in the bov by hand.

[MF DOOM]

Brokey. Open it up and see why its jammed

[kamotors]

thats exactly how mine is routed and right where it is placed and it blows off just fine. What spring do you have installed. The stiffer Tial springs wont blow off at low boost.

[Kozworth]

I believe it's an 11lber. Sucks cuz it is a b25 swapped eta, so I have no tach. Also, boost gauge acts kinda funny it doesn't really go up along with boost. If I sit at idle revving and the gauge does not go up in a linear pattern

According to the Gauge I did hit 15psi but did not hear a bov. The gauge is teed into map sensor and lines might be a hair too big.bibused zip ties to double check they would stay.

[Kozworth]

Edit: is there a way I could just use a vacuum gauge to test bov function off the car?

[MF DOOM]

There is a way. youtube it. im sure theres tons of videos. sounds like its just seized up. every bov ive ever touched ive been able to compress by hand

[Kozworth]

What would cause a seized bov? When I baught it a year ago or so off a kid on one of these forums, it looked hardley used.

[Kozworth]

So I took apart the bov. It is the unpainted spring. Everything was fine and moved freely as it should with the spring out. Installed ad I still cannot compress the bov.

So I have two ideas why it's like this and not working. First is I have a deleted iac so is it possible since the throttle adjustment screw is opened wider then a normal system that there is still a boost leak at the tb?

The second idea is the nipple at the top has a hole and so does the bolt that holds the nipple. I tried to line them up, but offset the hole into the diaphram(as opposed to lining up with the hole that goes to the spring chamber. Is there any effect on the relation of these two items?

Lastly I saw the bov hardly move this time around. It basically movies barely enough to expel boost and does not mak a sound.

[downforce22]

The tach can work if you hook up the wire from the car harness to wire pin 29 I believe

[MF DOOM]

^^ I have that in my notes somewhere. I know its a black wire, at least it is in a 91 car, but i dont remember what pin number. Ill try and find that to confirm it for you.

I dont run an iac either so im not sure about that. And if Im understanding you correctly the nipple and bolt dont have to be lined up perfectly. Air will flow through it just fine. Do you have another bov you can try using? maybe a friend has one laying around?

[Kozworth]

Unfortunately I do not have another bov laying around. Sucks because I paid a hair over 200 for this bov.. when I could have got a working ebay special for the forth of that.

If you could dig up the wire splice to get the tach to work, It would be greatly appreciated. Otherwise, I will be testing the bov with a vacuum pump and double checking to make sure that the evap port does not have something wedged.

I will also check the to see what my vacuum is at idle. The unpainted spring is set for 18-21 in/mg, and I would assume if my vacuum is less then <18in/mg the valve would never even reach the spec for it to open up.

[downforce22]

[QUOTE=Kozworth;3842368]Unfortunately I do not have another bov laying around. Sucks because I paid a hair over 200 for this bov.. when I could have got a working ebay special for the forth of that.

If you could dig up the wire splice to get the tach to work, It would be greatly appreciated. Otherwise, I will be testing the bov with a vacuum pump and double checking to make sure that the evap port does not have something wedged.

I will also check the to see what my vacuum is at idle. The unpainted spring is set for 18-21 in/mg, and I would assume if my vacuum is less then <18in/mg the valve would never even reach the spec for it to open up.[/QUOTE

This article:

http://www.strictlyeta.net/technical/328i_8.html

[Kozworth]

Ok thank you that would definately help out.

I tested the bov with a vacuum pump, it began to open ~18in/mg and really opened decent at around 20in/mg.. so the spring and unit as a whole is functioning properly.

I guess the only issues among this would be:

1) This spring is incorrect for my car because the idle vacuum readings might be below ~18in/mg, so the diaphram cannot open due to not enough vacuum.

2) There is some vacuum issue with the evap port, whethor it be carbon or whatever somewhat clogged eithor at the port or the line to the port.

[E30-323ti]

That sounds about right.

Remember, then the BOV opens it has ~18in/mg sucking on the diaphram and Xpsi of boost pushing on it - so should open fine, and then will close when finished venting / back to normal vacumn.

I'd be checking your vacumn source.
And also, rule of thumb is to not have anything Tee-ing of a MAP sensor line.

[Kozworth]

So I found the issue last night.

I had the idle screw set to the point of just being able to idle. It was 15in/mg. I opened it more even though an engine under load creates less vacuum, and I stopped it when it idled at 20in/mg. it actually blew off. So I have to definitely fix my tach to see my idle but atleast I have a working bov.