"P" Port for BOV Question

[spadepro22]

I've recently moved my bov from the front of the intake manifold (stock 1g) port to the "P" port on the tb so I could run my map sensor without "T"ing it and now bov flutters. Is the "P" port a good enough source for the bov?

I've read some threads on this but none had answers that I felt comfortable with.

 

[NHerron]

It see's both vacuum and boost, so yes it's good. I used it for datalogging.

Make sure the line is not kinked, tears, etc. With the engine running pull that line off and make sure there is vacuum there. If not, possibly carbon build up or the TB-to-IM gasket is in some way blocking.

 

[WES_393]

The P port does have both boost and vacuum, but the passage leading to it inside the TB is tiny. It might not be providing enough "pull" to open the BOV. So you may need to go back to using the larger port for the BOV, and then use the P port for the MAP sensor.

 

[NHerron]

Good point Wes. Since stockwise those ports are used for emissions mostly, the volume moving in/out in a short amount of time is much less than the bov needs to actuate.

 

[Spanky_DSM]

I thought the "p" port was a reliable boost/vacuum source.

Thats where i have my boost gauge line hooked up too.

Or does the pressure difference only apply to the BOV?

 

[WES_393]

It's certainly reliable in terms of reading pressure with a gauge or sensor, but that requires much less volume than operating the BOV. Especially if your BOV spring is pretty stiff or the diaphragm isn't the greatest.

 

[901gtsi]

The p port seems to work good for people for the map sensor vacuum source. But if your looking for a more permanent solution I would take the intake manifold off and drill and tap a vacuum fitting on the back of the intake manifold, there's a perfect spot next to the brake booster vacuum line then just zip tie the map sensor to the clutch master cylinder reservoir. This is what ecm tuning recommends to do for a 1g. Just something to think about. Hope I could help.

 

[killercolt]

Just t off the brake booster line fire the map or t off the bov vacuum line. The p port supplied by a tiny hole. I don't know if it can sustain enough air volume to keep the bov close under high boost.

 

[LandSpeed-DSM]

Just get one of these..

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Has to be one of my favorite mods on the car from a service/function perspective.

I don't like messing with my brake booster line, in case it develops a leak at one of the fittings.

 

[kchaazz]

^^ This. Also, regarding the brake booster hose, there is a check valve within the hose to prevent boost from entering the booster and blowing out the diaphragm, so if you do tee off the hose, make sure you do it on the part of the hose closest to the intake manifold side of things, though this isnt recommended.

 

[T is for TURBO]

Why mount the map sensor to the fire wall and use the 'p' port for the map and the stock bov port for the bov?

 

[LandSpeed-DSM]

Why mount the map sensor to the fire wall and use the 'p' port for the map and the stock bov port for the bov?

Are you asking me?

My purposes make it more convenient to have the bulk of my peripherals mounted on the vacuum block. It provides a bit of a buffer and the logged MAP values are smoother with those intake valve event pulses softened. It also removes it a bit from the vibration and heat the manifold imparts on sensors mounted to it.

That's an old picture, but I run all AN lines to my boost/vac referenced valving.. the block makes it easier to get a wrench on the hose ends.

 

[T is for TURBO]

Lol, no, I'm asking the OP, sorry

I do like your rack of nipples though

 

[LandSpeed-DSM]

Nipples rule.

 

[T is for TURBO]

That they do, that they do.

 

[MY1GDSM]

So you may need to go back to using the larger port for the BOV, and then use the P port for the MAP sensor.

OP,

Do NOT use the P port for the Map sensor...

I/You want to it on plenum and not that close to the Throttle Body.

My Best guess is that the Gasket is blocking the Line slightly or your Bov (if adjustable) needs a little less spring pressure)

Really if you can't get that line to work just pick up a vacuum clock like Landspeed posted and run all the lines as short as possible.

Also I don't care what anyone on here says... DO NOT T- anything if you don't have too, If you need another Boost/Vacuum source make one... .

 

[T is for TURBO]

Do NOT use the P port for the Map sensor...

Can you elaborate on this? I have mine on the 'p' port currently. The only issue I seem to have is I can't quite get my boostest to line up with my map sensor. Boostest reads 3-4 psi higher.

 

[LandSpeed-DSM]

Boostest reads 3-4 psi higher.

That discrepancy and where it occurs is a function of your VE table.

 

[T is for TURBO]

That discrepancy and where it occurs is a function of your VE table.

v2.5

 

[wkmitsu]

... But if your looking for a more permanent solution I would take the intake manifold off and drill and tap a vacuum fitting on the back of the intake manifold, there's a perfect spot next to the brake booster vacuum line ...

This is exactly what you should do for your boost/vacuum source. You technically shouldn't T off anything. If you drill and tap for a source and need more than one, like someone else mentioned, you can get a vacuum distribution block. It'll be cleaner and better.

 

[NHerron]

Not 100% on 2G manifolds but I noticed on my 1G mani, there are two 1/8 plugs on each end of the mani. Where the PCV hose connects, follow that raised casting in the mani and you will see them. Personally haven't used them but it's something to look into.

 

[spadepro22]

Just get one of these..

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Has to be one of my favorite mods on the car from a service/function perspective.

I don't like messing with my brake booster line, in case it develops a leak at one of the fittings.

What source did you use? Im going to order this tonight.

 

[LandSpeed-DSM]

Drilled and tapped an out of the way spot on the plenum, centrally located in the hopes it will buffer the signal a bit.

Its got a -6 line run to it.

 

[Tiki2777]

wait, so where do most people get a source for their vacuum blocks from?

 

[spadepro22]

wait, so where do most people get a source for their vacuum blocks from?

Yep, this.....Hope I don't have to pull the manifold because that would defeat the purpose of me getting the block.