rwtf

Alright, s14 sr20, my boost gauge is only reading a -10 or so vac, from what I've read it should be 20....

There is only 3 vac sources being used...

First is of course the FPR
Second is the BOV on its own line under the TB
Third goes from the WG then Ts to the boost guage then goes to the second spot under the TB.

Is this right? I know the 1st and 2nd are but the 3rd I'm not sure about....

It idles kinda rough and backfires a shit ton under boost.

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jr_ss

The vacuum sources are lines that come from the middle of the intake manifold. If you are using the ports on the throttle body, they only see boost reference.

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My SR20VET

rwtf

not sure what you mean....

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jr_ss

Alright, there are two ports on the actual throttle body itself. They only see boost because they are before the throttle plate. There are 3 metal hardlines running from under the IM towards the throttle body. One is for your IACV the other small lines are vac sources to be used for whatever you see fit.

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My SR20VET

rwtf

yeah, the other two are what i'm talking about...

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jr_ss

Do you have any open lines? There is also one for the PCV and one for the brake booster, but those are located on the back and side of the IM. What type of BOV are you running? Is it vented to atmosphere or plumbed back into the intake tract after the MAF/before the tubo?

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My SR20VET

91ka24

You shouldn't run your boost gauge inline with your wg. Boost gauges need to see there reading from the intake manifold directly. So on your tb there are 2 vac ports, 1 needs to run to a t fitting, then off of the t, one lines goes to the fpr, the other port goes to your boost gauge.then the 2nd nipple on the tb needs to run to your bov. Now go get a brass fitting with a barb and drill a hole on the under side of your hot pipe,thread in the brass fitting, then run a vac line straight from that brass fitting to your wg. If you even run a boost controller just t it in between that fitting and your wg.

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Follow me on Ig- Andydennington

rwtf

alright i'll post a pic of how its setup atm...

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Mikester

Miguel?

Anyway, although it can be done; it's never a good idea to tee anything off the FPR source; except maybe in a short-term pinch. Don't get me wrong- I drove like that for longer than I'd like to admit in Japan & never had any problems. However, I was lucky and quite frankly I didn't know any better 'till later in life. If I WERE to have developed a vac/boost leak there, the results could very likely have been catastrophic. The FPR needs to be able to add pressure as the boost goes up... If it's tee'd & there is a leak at/in anything connected to it; shit leans out real quick and bad stuff happens in the combustion chambers...

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jr_ss

The ports on the S14 SR throttle body are not vac sources. They are drilled right at the throttle plate. They must be after the throttle plate to see vacuum.

Never T off on your FPR line. That should remain on its on line at all times.

The wastegate only needs a boost reference, so it does not need vacuum. (Use one of the throttle body ports).

Like I said previously, those metal hardlines that run from underneath the upper manifold are vacuum sources. The FPR should have its own source on the side of the IM. Use the two below for your BOV, boost gauge, or whatever vacuum needs you have.

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My SR20VET

rwtf

Well the reason why i'm asking is because i'm reading like -7in/hg vac and it should be -20 or so.... also it breaks up under boost at 4k then stops wanting to go and backfires like a mofo.

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Mikester

Make SURE your FPR is plumbed to the intake properly; then look elsewhere. Sounds like you have a leak somewhere.

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rwtf

yeah its on its own vac source on the inside part of the intake.

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rwtf

Here is my vac line setup....

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jr_ss

Wastegate doesn't need vacuum. As stated, there are two nipples on the throttle body you can use for that.

Have you done a leak down or comp test? Was the car running fine then lost vac at idle? Typically, vac at idle tells you how healthy your motor is. With you only pulling -10in/hg it leads me to believe you have a large vac/boost leak somewhere. Take a spray bottle with some soapy water with the car running and hit your couplers or gasket areas.

Put your hand over the BOV discharge area at idle. If you feel air being pushed out, there is part of your issue. What is mech timing set at? How about idle rpm? Is it at 750?

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My SR20VET

rwtf

oh okay.

when I first crank it its jumps to 2k idle then slowly goes down to around 1k, and has a rough idle, which leads to me to think vac leak also, I remember the same crap on my KAs.

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rwtf

What are some common vac leaks on a s14 sr20?

Also whats the best way to find them? Can i use brake cleaner?

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Mikester

^^If it has boost and/or vacuum pressure going to/thru it, give it a look. "Common" leak areas depend on the current setup & the current owner

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rwtf

Well I sprayed MAF cleaner all over my Vac lines and what not and no change in idle, but I do notice it get rougher(if thats a word) when the motor warms up, it will read like -7 in.hg but If I rev it up a tad its hesitant then the vac will go to -10 then slowly go back to -7.

wtf is going on

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jr_ss

Do you have your timing set correctly? It should be 15degrees BTDC.

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My SR20VET

rwtf

I'm not sure. altho I'm certain it is.

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ultimateirving

This made me lol...


Sounds like a boost leak is ur issue with it breaking up. And I also had an issue with my boost gauge being t'd from the wrong spot it would only read -10 vac.. Then I figured out I had a bonehead extra vac line and after I removed it my gauge would read the normal -18 to. -20 vac..

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Z32 with lq4 swap
Desert Street Scene || Dssevents.com

rwtf

I checked all my vac lines, see my pic with crappy ms paint, thats exactly how its setup. And It has a kinda of a rough idle.

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ultimateirving

When was the last time you boost leak tested it young man?

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Z32 with lq4 swap
Desert Street Scene || Dssevents.com

rwtf

Well Ive been doing some research and got what I need to make a tester, also got new vac line i'm going to run.

so the way ive seen to boost leak is make a fitting on the turbo inlet and basicly pressurize the whole system with a Aircompressor.

So do I need to unhook anything and plug it?

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rwtf

bump :/


msglength

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cotbu

Block off anything that will allow air into the crank case or valve cover.
You should pressurize the intercooler and pipes 1st, then with a lower pressure check the remaining system. Most common leaks would be BOV and it's flange, any welds, and coupler. spray those with soapy water. If you have leaks repair, then pressurize the rest of the system with about 5-7psi. common leak areas are, fuel injectors insulators, valve cover, brake booster and it's vacuum line and PCV.

I know you said your vac reading is low, but is the idle high?
You may have more problems then just a boost/vac leak. if you pinch the PCV line at idle and the idle lowers and vac increases? Clear indication of a boost/vac leak, but if only the idle decreases well.... you have work to do. Timing could be off, etc.

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LoverTechnologies "Half Broken Things!"

Kingtal0n

One of those vacuum sources is not vacuum source, it is transient throttle source, and only will see vacuum when the throttle is open somewhat. You might already know that, but just in case you overlooked it...

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rwtf

The idle when first cranking up the car jumps to 2k then slowly creeps down to 1.2k then down to where its suppose to be but the idle is pretty Consistent, I'm going to check my spark plug gap and my timing and run a nipple on the hotpipe for my WG

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rwtf

BUMP!


fsdfsdgsdfcdgrefg s

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