Boosting to 20 psi WOT NO MODS

[lilrob2069]

Here's the problem, if you check my mods list all i have done is removed the Boost Solenoid. Added a K&N, and 2.5 in downpipe to 3 in. after all the way back. I haven't really done any hard pulls. But the other night i decided what the Hell, Why not. So I'm getting on the Highway in 3rd gear and running about 3500 rpms, Gas it and push it to almost full throttle and watch my boost gauge shoot up to 15. Gave it a little more gas and it went to 20 psi. Thought maybe it was a fluke so I tried again. Sure enough it boosted to 20 again. So later the other night i decided to do a regular 3000 rpm pull and brought the boost level up to 15 in 2nd gear, 20-21 in 3rd gear, and 15 in 4th gear. What doesn't make sense is I thought that these cars were suppose to fuel cut at higher than 15 I maybe mistaken. Please anyone help me figure this out. I've checked vacuum lines though I'm not for sure what i am looking for.

 

[onefast2gdsm]

Here's the problem, if you check my mods list all i have done is removed the Boost Solenoid. Added a K&N, and 2.5 in downpipe to 3 in. after all the way back. I haven't really done any hard pulls. But the other night i decided what the Hell, Why not. So I'm getting on the Highway in 3rd gear and running about 3500 rpms, Gas it and push it to almost full throttle and watch my boost gauge shoot up to 15. Gave it a little more gas and it went to 20 psi. Thought maybe it was a fluke so I tried again. Sure enough it boosted to 20 again. So later the other night i decided to do a regular 3000 rpm pull and brought the boost level up to 15 in 2nd gear, 20-21 in 3rd gear, and 15 in 4th gear. What doesn't make sense is I thought that these cars were suppose to fuel cut at higher than 15 I maybe mistaken. Please anyone help me figure this out. I've checked vacuum lines though I'm not for sure what i am looking for.

The 3 inch exhaust is causing the Turbo to spool more freely and is causing boost creep. Also doesn't help that you removed the bcs restrictor. That being said, my gs-t spikes to 18 in every gear because I removed all restrictions in the intercooler system. That is also on a t25.

 

[lilrob2069]

The 3 inch exhaust is causing the Turbo to spool more freely and is causing boost creep. Also doesn't help that you removed the bcs restrictor. That being said, my gs-t spikes to 18 in every gear because I removed all restrictions in the intercooler system. That is also on a t25.

See, i was explained that removing the Boost Solenoid it would only raise my boost level to 14 max. that's weird. So im guessing i need to install a Boost controller soon. And not do any hard pulls until then.

 

[delta448]

Reconnect the vaccum line to the wastegate actuator from the charge piping or intake manifold.

 

[95gst16g]

Just run a vacume line from the wastegate strait to the compressor housing and see if that solves the issue...

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[lilrob2069]

The way i have mine ran is the line off the actuator and jpipe come into a tee and then that line is tee'd into one of the vacuum ports on the intake.

 

[95gst16g]

Plug the hole in the intake and run a strait piece of line from the actuator to the j pipe and try that.

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[lilrob2069]

so delete the tee that the actuator and J pipe connect too and just connect them together without the line going to the vacuum port on the intake.

 

[9!'clipseDOHC]

so delete the tee that the actuator and J pipe connect too and just connect them together without the line going to the vacuum port on the intake.

Yes. Did you just make up your vacuum route? Also stop doing pulls until you fix your boost creep problem or you will have a much bigger problem on your hands. Also a MBC won't lower your boost. If you hook up your vacuum line from the j-pipe/compressor to the wastegate actuator and it's still creeping then a MBC won't help you. At that point you will need to port your o2 housing or upgrade to an aftermarket one. First, run your vacuum line correctly though and see if that takes care of it.

 

[lilrob2069]

Yes. Did you just make up your vacuum route? Also stop doing pulls until you fix your boost creep problem or you will have a much bigger problem on your hands. Also a MBC won't lower your boost. If you hook up your vacuum line from the j-pipe/compressor to the wastegate actuator and it's still creeping then a MBC won't help you. At that point you will need to port your o2 housing or upgrade to an aftermarket one. First, run your vacuum line correctly though and see if that takes care of it.

No actually this is stock. the vacuum line coming from the J-pipe comes to a tee, which is also what the vacuum line from the actuator goes to. then there is a line that goes from that tee to where the BCS was. I unhooked it and deleted the BCS completely, ran the line that went to that, to a line on the Intake manifold. Now also could the reading be off because of the Boost Gauge being tied into the Fuel pressure regulator line. And yes i am done doing WOT pulls, for right now. but when i don't do hard pulls like that, the boost stays at 10- 11 psi.

 

[BoostedBeaver]

Have you tried what everyone has said???? You need to do the single piece of hose from the actuator to the J-Pipe. After you do this let us know if it stops.

 

[lilrob2069]

Have you tried what everyone has said???? You need to do the single piece of hose from the actuator to the J-Pipe. After you do this let us know if it stops.

oh i will, im at work so i can't go toy with it right now. But i will get to it in a little bit.

 

[LandoAWD]

The gauge tapped into the FPR reference is fine, and I'd wager most of us have it that way. BOV and WG should, when possible, have dedicated lines.

FWIW, the point about boost creep is a big one. I had an Apex DP (not true 3") and 3" exhaust on the old car behind a 16g, and keeping it under 20 was a struggle until I upgraded the flapper.

 

[95AWD6Bolt]

Since when did "no mods" equal a downpipe, exhaust and filter?

Anyway, listen to what the guys on here are saying, when you open up the exhaust from stock to 2.3, 3", etc; you allow the turbo to spin more freely.

 

[9!'clipseDOHC]

No actually this is stock. the vacuum line coming from the J-pipe comes to a tee, which is also what the vacuum line from the actuator goes to. then there is a line that goes from that tee to where the BCS was. I unhooked it and deleted the BCS completely, ran the line that went to that, to a line on the Intake manifold. Now also could the reading be off because of the Boost Gauge being tied into the Fuel pressure regulator line. And yes i am done doing WOT pulls, for right now. but when i don't do hard pulls like that, the boost stays at 10- 11 psi.

I know how the vacuum lines go stock, but once you remove the BCS (an integral part of the stock boost control system), it is no longer stock and you need to modify the vacuum line route.

The FPR is the best place to tap for a boost gauge, in my opinion, so that is not the problem. It sounds like you can trust your gauge.

Let us know what happens when you run the line from wastegate to j-pipe/compressor cover.

 

[lilrob2069]

Ok so i did what everyone said, and ran 1 line from the actuator and J-pipe. No there was no change. Now i also noticed the 4 vacuum lines from the intake down to what looks like a sensor going into the thermostat housing. My question is are lose lines needed? And does coolant run through them? Cause i noticed coolant coming out of one of them.

 

[95gst16g]

I don't really know what lines you are talking about.But if there was no change running the line like we said you are probably experiencing boost creep.that's pretty common when using a bigger exhaust.Do you still have the cat? If not its probably causing the creep by having a lot less restriction.

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[Prib9671]

I had the same problem, bad boost creep. Just go buy a better o2 housing and problem solved. You can try to port the stock one but it didn't work that great for me. I would also suggest porting you exhaust housing on the turbo where the exhaust flows out of the WG passage that seems to help a lot as well. Good Luck.

 

[delta448]

Now i also noticed the 4 vacuum lines from the intake down to what looks like a sensor going into the thermostat housing. My question is are lose lines needed? And does coolant run through them? Cause i noticed coolant coming out of one of them.

There are coolant lines that supply the Fast Idle Air Valve in the Throttle Body, but as far as I know there shouldn't be any connections between the T-stat housing and the intake manifold.

Here's the stock 1G vacuum diagram.

As for the original problem, I would suspect boost creep, but I'd recommend that you check the wastgate flapper arm and make sure it isn't stuck. Does the boost build slowly or can you go from 12psi to 20psi with just a little stab of the throttle?

 

[9!'clipseDOHC]

There are coolant lines that supply the Fast Idle Air Valve in the Throttle Body, but as far as I know there shouldn't be any connections between the T-stat housing and the intake manifold.

Here's the stock 1G vacuum diagram.

As for the original problem, I would suspect boost creep, but I'd recommend that you check the wastgate flapper arm and make sure it isn't stuck. Does the boost build slowly or can you go from 12psi to 20psi with just a little stab of the throttle?

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You can see on this diagram that of those 4 vacuum lines coming off the throttle body, 2 of them go straight to the thermo vacuum valve, which is attached to the front side of the thermostat housing. From there the go to the EGR valve and control when it opens. These are vacuum lines only. There is nothing going threw them but air. You can remove the entire EGR system, many do and have (including myself).

After blocking everything off the vacuum lines should look like this (EXCEPT for the MBC, Don't tap into the BOV line).

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Hope this helps!

 

[lilrob2069]

Ok, that's what i thought, could it be possible that the thermal valve is broke causing coolant to come through it?


Now to Answer Delta's question, when i go any more than 3/4 throttle it will got to 15 psi, in less than 3 seconds, then it take another 3 seconds for it to go to 20 psi.

 

[delta448]

Ah! Good catch! Forgot about the EGR, I always get rid of it on my cars.

The only ones you have to keep are; BOV, FPR, Wastegate, Positve Crankcase Vent, and depending on how you set it up, the valve cover vent.

Just don't unplug any of the emissions solenoids or you'll throw codes.

 

[lilrob2069]

can i ask why not to tap into the BOV line. i haven't put one on yet but im just wondering

 

[LandoAWD]

Search Results - DSMtuners

These are my Search results for "tap BOV line"

 

[delta448]

Kris, your link didn't work for me.

Here's why you don't tap the BOV line:

There are many reasons why one shouldn't tap the BOV line and acuracy is only a small part, the biggest problem is proper functioning of the BOV. The mbc will end up bleeding pressure off the line causing the BOV to open under boost. The situation is made worse if the mbc is a bleeder type which is also a vacuum leak off boost causing the bov to react slower when letting off.