Rpeck

I have had this problem since I finished this build.. But my car does not start to boost well until about 5K+ RPM's. I read posts of people with similar setup's saying they hit 10 PSi in 2nd gear at 3k!!! I have been searching and searching for a problem but everythigg checks out okay. I have checked the wastegate operation a trillion times, so it has to be somthing besides that.

I am open to any and all causes of this.

Mods listed in Sig. On the dyno I was boosting over 12PSI at 8.5K the high end boost is great! And it was still not dropping off. I just don't quite get why I have such weak low end boost.

P.S. This is a pic of day one on the dyno, day 2 i hit higher PSI, but the same curve.


Thanks,

Robert

BLUE TII

iTrader: (9)

You are not doing this on stock IC are you?

RETed

Are you running a cat???
What does this "custom made cold air box" look like?


-Ted

BLUE TII

iTrader: (9)

What I meant is the stock IC/intake could be creating such an intake pressure drop at the CFM you are trying to move through it for that compressor/port set-up that is it impeeding spool as well as boost.

However, be careful decreasing your intake pressure drop- your set-up w/ a decent intake manifold/IC should see over 20psi by 3,000rpm in boost creep!

For instance,

I have almost gotten to where I can keep my BNR stage 4 (more free flowing T4 exhaust side "O" trim clipped 15 deg) from creeping over 20psi by

adding open end HKS GT 60mm wastegate and WG passages as large as the stock casting can support

boring the turbo housing to sloppy fit w/ wheel (~1/16" clearance)

machining the housing so both scroll's apertures are 10mm and the rear is more rear facing

And lots of other stuff (when you can search- do so).

A real problem trying to controll boost creep w/ a wastegate is you actually almost always increase total system flow as well as WG flow.

I was beginning to think I had boost creep under controll untill I was able to go to 8,000rpm instead of the 7,000 I had been stuck at (hitting 100% inj. duty cycle too early).

Rpeck

I am running the stock IC at the time being. I plan to get a FMIC, but not if I can't fix this problem ... I can't see dumping another $900+ until I get it right how it is. I figure if anything the stock IC should create boost sooner than a FMIC.

At this point if I pull the wastegate hose and gun it I CANNOT create over 10 PSI so the least of my worries is spike right now. i think I have a massive leak somewhere. My theroy is that it is creating boost like it should all the way through the power band, but it is leaking boost off somewhere but it cannot leak off quick enough to stop the boost at the higher RPM's.

Here is a pic of my intake Ted;

don't mind the ducttape, thats just so the clamps don't scratch my paint job inside, it's all properly clamped underneath the tape. Also I have removed the "Box" on my inake at the moment to make all this trouble shooting easier to get to.

Edit; Forgot, nope No CAT, free flow and loud all the way back. RB downpipe 3" all the way to a 4" Y-pipe that splits to 2 3" to my dual Apexi's N1's


If you have time... 2 more related threads; that contain more info and pics.

here

and here

Sorry I have posted this on multiple forums's but I have rebuilt this myself, dode every single mod and install myself.. and up till now been able to fix every problem (with help from the forum) myslef. But this one has just got me stumped... I am at a total loss, and I am going on months now .. really months with this same issue

Rpeck

BTW; I have had my IC pressure tested no leaks in the IC.

BLUE TII

iTrader: (9)

Yes, if you had a boost leak that impeded spool that badly and still boosted up to 10psi at the CFM a large streetport moves your turbo would have spun itself into a shrapnel grenade-

Or so I imagine...

BLUE TII

iTrader: (9)

My theroy is that it is creating boost like it should all the way through the power band, but it is leaking boost off somewhere but it cannot leak off quick enough to stop the boost at the higher RPM's

Ah, a boost leak does not radically get worse as pressure increases. Possible.

What BOV are you using?

BLUE TII

iTrader: (9)

Does it sound like a boost leak?

My experience w/ boost leaks- turbo sounds like it is spooling extremely easy and loud despite low power output followed by very loud hissing sound especially once positive manifold pressure is realized?

importboi22

what a second!!! you still have vaccum till 3k!!?!?!?! check to make sure your throttle body is opening all the way please....

BLUE TII

iTrader: (9)

I just read that too.

Your 2ndary throttle plates dampner is sticking on the cam Rpeck!

-edit- careful the 1st time you fix it and boost

You are going to have insane boost creep!

Rpeck

BLUE, my exhaust is soooo loud I can't even hear the turbo. I can just barley hear my BOV.

I am using a TurboXS Type-H BOV. I popped all the washers it comes with in that thing (just as a test, and since removed them) no help. And the type H is suposed to hold up to 30 PSI when fully loaded. I also popped on the stock BOV just to test low end boost, no change.

importboi22, I will check that first thing in the morning .. I don't feel any restrictions, but like I said I will try ANYTHING at this point. I got tommorow off thankfully, good ole columbus

P.S. my secondary throttle plates have been removed.


Thanks for your input fellas,

-Robert

Rpeck

if you guys really really think its the trottle plates, I will go out in the garage right now... have you seen this before?

I don't think I mean secondary plates removed, I mean the second set of them... you know what i'm talking about right?

BLUE TII

iTrader: (9)

BLUE, my exhaust is soooo loud I can't even hear the turbo. I can just barley hear my BOV

Ah, you are not spooling the turbo at all. My exhaust is much louder than yours and you hear the turbo just fine (3 1/2" turbo back 1 straight through "muffler").

We mean your 2ndary throttle plates, not your 2ndary throttle plates 2ndary set.

Be very careful when you fix it

20psi by 3,000rpm- is your ECU good for that?

Rpeck

Not sure about the ECU, it has been modded as close as they could get to my Mod's. But if I fix this issue i will make more $investments$ to get it all right. This is just so frustratng it has thrown me off the whole car.

But i have the low stage of my boost controller set at about 9 PSI, and the wastegate is ported, I will go easy for sure if it starts to boost right to avoid bad creepage.

Okay i am headed to the garage, i will check in every 20 mins or so, if you have any other advice...


LOL, boy will my neighbors be pissed when i fire this up tonight

Whan you say i am not spooling the turbo... would this throttle plate issue cause that i assume?

Rpeck

hmm, another thing? what would hang those up? I need to crack open the UIM right? somthing internal hanging it,. or you think somthing external could be doing it?

BLUE TII

iTrader: (9)

As my 1st post indicated

Too much pressure drop in the intake tract.

Don't let your next post be "blew the engine"

My POV is the only thing that saved my engine the 1st time I boosted the BNR...

BLUE TII

iTrader: (9)

No

The dampner (looks like dashpot) has been smashed down into the cam on the 2ndary shaft whan you dropped the mani on its top.

1 second fix

-edit- bend or screw dampner back upward if you didn't get that fix...

BLUE TII

iTrader: (9)

yea-edit- that was a reply to the below question

Rpeck

Blue, you still with me, I am taking a pic...

BLUE TII

iTrader: (9)

Wait is this pic on film or digital

I am going to bed in a few hours

Rpeck

Damn, wont let me post a pic for some reason I think it fugged up though .. its moving all over it comes on and out, moves all around I THINK YOU GUYS FOUND IT!!!

BLUE TII

iTrader: (9)

OK, now ease into the throttle after you fix it.

It seriously felt like Satan slapped the rear end of my poor FC the 1st time I boosted and it crept to over 20psi somewhere between 3,000 and 3,500 rpm. I thought this meant that is where the Pineapple Stage 2 really started to breathe, uh uh- once I got creep more under control I found out it comes on at 5K.

I have my old relieved turbo backplate and downpipe/muffler for externally venting the stock WGs.

All you would need to do is make a divider for the turbine to WG flow and bolt it all together- let me know if you are interested...

-edit- oh, by the way. It was in 5th on the freeway that satan smacked my FC's *** end...

-edit-eidit- can't spell

Rpeck

Right on! I can't wait to give it a shot, I am now %99.8 sure this is the problem, I might need a whole new one though .. it's comming in and out from the throttle body, i think something might be disconected inside. I will have to take it apart first thing in the morning.

I think the thing is moving, but it is not lined up with the white plunger gizmo... thus not making it operate right. Finding the problem 6 months, fixing it; 1 Hr. LOL, aint life a bitch sometimes...

BLUE TII

iTrader: (9)

Ah, OK- the plate's shaft is moving in and out?

I never messed w/ the TII TB/ UIM so I am not familiar w/ fixing the problem you describe.

-edit-

Let me know if you want me to send my '87 TB w/ the WG external venting stuff.

You have no way around externally venting the WGs and it probably will NOT be enough.

You don't have to remove the turbo for my parts, just the DP and backing plate and then make a slug (I will see If I have my templates still) to block WG flow from DP flow and bolt my backplate WG downpipe/muffler on and then your DP again.

Externally vented stock flapper leaks at idle that is why the DP/muffler for it.

Search my username for info/pics when search is working again.