DSM Guru's need advice on boost issue

[DsmRacing]

My boost gauge is saying that my car is hitting 26psi, when the dsmlink shows 30.3 air flow (if confused or don't believe me, contact Jake v413nc3) approximately 23-24psi. Now the same thing happens when I turn the Hallman MBC down and the airflow is showing something in the 20 range (15-16psi or so)...but the boost gauge is showing 24+psi.
One more odd thing is that my car had a huge boost leak, a 1/2" gash in one of the couplers, and the car was slow, but showed 24+??? I have fixed that, the car feels pretty strong, but have concerns.. I only want to run 20-21psi max right now......
My turbo should not be able to run high boost, not here or I guess at sea level, the air flow that I registered, according to Jake is too high for this elevation.

Anyhow, Jake and I are at a lost for this, I doubt my boost gauge is bad, it works like it normally does, but I am going to buy an autometer and see if that is it, but again, I doubt it. I am looking for other suggestions, please help.

Here are some important details:
-Mistake but should not matter for this issue- valve cover vented into atmosphere, straight down to the ground.
-Big T28
-Apexi FMIC
-dsmlink
-190lph
-660 ND's
-3"turbo to tip
-apexi mechanical boost gauge
profec is still installed with no stepper motor, but the vacuumm source is still ran to the unit.

Chad
very frustrated
"$1K dog stolen, replaced with sometype of Husky, damn I hate thiefs!!!!"

p.s. Jake if you read this, please add to it so that it makes more sense, and has more technical info to it.

[v413nc3]

Ok... so here is a little to add to it...

We've seen BT28's here hold 17-19psi (Brock, Mandy, Chris Webb)... We've also see that they won't hold their max boost up here... even when not even running a WG actuator...

Chad's boost gauge SPIKES to 27 and then falls back to about 20-21 where we believe it is set, but in the logs all I show is a steady climb of air flow from about 4.5lb/min to around 28-29lb/min (we even had one pull before we turned it down of around 30.3lb/min which is about as close to what that turbo can put out at this elevation as you can get)... Now based on the compressor maps of a Big T28 (and since his boost gauge reads all kinds of wacky) I assume that he's running around 24psi @ 30.3lb/min and about 20-21psi around 28-29lb/min... Yes I have taken into account that the spike and fall off could be from his wastegate opening and controlling boost, but lets assume for a minute that no one has really seen 27+psi on a BT28... I don't think it can really do that...

Now as far as tuning goes I've got the car close to tuned good, there seems to be a surge in knock (from about 1deg to 3.5deg) around 5-5.5k RPM... which is hard to correct for and then it falls back to around 1-1.5degrees of knock above 5500RPM (as read by DSMLink v1)... We were getting a great deal more knock retard before I moved his global settings from about 35% to 31% (660cc injectors)... I forgot to save the logs with the 31% settings but I can post the logs from running 20psi and 35% global if needed...

I just think it is weird because when we FIRST took out the car we had it set to 16psi, it would shoot to 16 and stay there rock solid (as per his boost gauge). All his settings were zeroed out and I was able to add timing and cut fuel to get it to run very nicely. Then we tried turning up his boost via the profec and it wouldn't go abouve 16 at ALL (as per his boost gauge). So we decided to just remove the vac line to the WG actuator. After doing this the car would shoot directly to 20psi (on the gauge) and stay there, not go past at all... after adding a great deal of fuel and cutting some timing I was able to get it tuned initially to 20psi without too much knock. This is where Chad headed home for the night, having the car run pretty well (barring some phantom knock at 0psi and about 3-5k rpm from his old style lifters)...

A few days later Chad was out and about with a friend of his and it started showing (on the gauge) PAST 20psi to 25 and sometimes 27psi. So he hooked the profec back up to the WG actuator and braught it back to me, where we connected a MBC and though the Gauge still read 27psi spikes falling to 21psi or so after some tweeking we started to just ignore the gauge and go off lb/min airflow numbers in DSMLink since the gauge wasn't IMO acting right (or changing at all for that matter) but the airflow was changing with changes to the MBC in DSMLink.

Any ideas what is up with the gauge?

[DsmRacing]

Some good news and bad news. Another dsm member and I tried out his brand new C/F boost gauge. Plugged it in where my profec B was. Guess what, they both read the same...25psi!
I am lost and frustrated now, any help would be more than appreciated, I want to get some track time, but need to resolve this issue and a few others.
Thanks,
Chad

[ImolaFem]

Why don't you just pressure test?

Make a fitting for the intake of the turbo and attach a boost gauge to it there. Pressure test the system and compare what that boost gauge says vs the one in your car. Very simple to rule out.

[v413nc3]

Chad, tap your boost gauge off the FPR instead of the TB... we're thinking it might be the reason for your wacky readings.

[nefkntym]

definitley tee in your boost gauge in between the manny and the FP solenoid. you will get a more reliable reading from there. make sure you dont tee in from the solenoid to regulator

[DsmRacing]

Just so everyone knows, the boost gauge is tapped from the intake manifold, as stated in the VFAQ. The car with the wastegate open (no line to the wastegate), used to hold rock solid at 20psi. Now with it the same way and with a hallman, the readings 20-27psi. Currently it is hitting 25 and falling to 21 in 2-4th gear.
I spoke to a guy at FP, and he has not heard of the turbo holding that much boost, even at sea level. The only way to get 27 psi, was to run an external wastegate. He suggested that I attatch a line from the compressor housing to the wastegate, and I only should read 10-12psi. I'm doing that now, I'll post the results in a few.
Chad

[DsmRacing]

Jumped on the freeway, and I was hitting 18psi and falling to about 15psi! Does that mean that my wastegate is shot?
Chad

[nefkntym]

is your wastegate passage ported? are you running a stock O2? if so is it ported? your spike/boost creep is caused by not being able to bypass enough exhaust gases throught wastegate passage fast enough. i had the same problem with my 14b. so when i got my big16g i ported the hell out of it down the throat and blended the porting into the wastegate passage. next i took off the stock wastegate flapper, ported some more and then put on a 34mm flapper. then i made a 2.5" tubular O2. after all that i mounted it.never any boost creep and i am still running the same 2.5"/3'' exhaust that i had on my 14b.
"when in doubt port it out"
:)

[v413nc3]

It's not a boost spike or creep... like I stated the climb in airflow is linear even though the gauge does not read it correctly. His wastegate actuator is bad though we have come to determine.

[hoffman]

wow, this is freaky.

so if his wastegate actuator is bad, and others have tryed running with none at all, how the hell is this turbo seeing such high levels? is it just a freak turbo?

[DsmRacing]

Well, I am tired of this freak turbo. Here is the new scenario! Swapped wastegates per Robert at FP and several others. Hooked the wastegate to compressor side of turbo (little nipple on the T25), and I was hitting 15psi consistently. 3psi more than Robert said I should be seeing. So I thought, its working correctly, so for the hell of it, I pulled the wastegate off again, and I was hitting 24psi, and then falling off to aobut 20-21. So, I figured I would hook up a boost controller (hallman mbc) inbetween the wastegate and compressor housing, now I'm hitting 24 psi and falling off again. I am going to try to adjust the mbc and go for a freeway run, and see what I hit, but I am lost for why this is happening. A week ago or so, the car ran great, and held 20psi rock solid through all gears, now I am getting this crap. Boost leaks would hinder me right? I am getting frustrated!
Chad

[ImolaFem]

I thought you were only using that boost controller for a couple of days then dropping it back off?

[DsmRacing]

Jake sold it to me, I just forgot and have not a chance to drop the money off.
Tired of running 15psi Take his for now....:D

[ImolaFem]

Ah, he neglected to tell me that. He said you'd be returning it in a couple of days.

[nefkntym]

how are you hooking the manual boost controller? is it hooked up from turbo to nipple on intake pipe and tee'd to wastegate actuator or do you have a line tee'd off the bov line going to MBC and then going to the wastegate actuator ?

[nefkntym]

i read you post again and doesnt look like you have it hooked up either of those ways. the first way i stated is the way RRE hooks them up. the second way i stated is the way TABOO hooks it up. both ways will work but since the TABOO way is off the line going to bov you might see some flutter with it.

[DsmRacing]

I actually am still dumbfounded on this one; no matter what I tried with the wastegate unplugged or a MBC, I could not get solid boost, it was all over the place. So, I put the profec back in, ran the IN to the compressor housing, the OUT to the wastegate wtih very short lines from the stepper motor. Tuned it again, and we were able to get rock solid boost @ 20psi! Good for a 13.2 pass at 102 mph!
No idea what the fix was, but very happy with the results.

[nefkntym]

glad to hear it sorted it self out...wish my car would do that with part throttle knock:)