BauleyCivic

*It was my exhaust that was causing the problem. I recently upgraded to 2.5" piping from the cat back (from stock piping), and my boost drop problem is gone.

Similar thread:
https://honda-tech.com/zerothread?id=849644


I'm having the infamous problem with losing boost with the greddy kit. Turbo is a 15g TD04H w/ internal wastegate. I have the vacuum line for the wastegate T'd into the FPR, and the BOV T'd into the PCV valve. The nipple on the compressor housing is capped off.

The turbo spools to .35 bar at around 5000 RPM, and then steadily drops to .27-.29 bar by redline. I'm wondering if a MBC will fix this, because the car has absolutely no top end. Any ideas welcome!

Joseph Davis

Sounds like the wastegate opens, then sticks open.

Check for binding in the wastegate actuator linkage, and you might have to tear everything off to see how the wastegate flapper seats. If you've clocked the turbo at a bad angle, it can cause the actuator arm/linkage to bind.

boostincoupe

*shrug*

Maybe your WG actuator's going out?

OR

Maybe it's your vacuum setup? Mine is as follows:

-BOV to brake booster
-WG to FPR
-Boost gauge to cruise control line
-Compressor capped off

I've never seen a vac. setup running to the PCV, so you might want to try switching the WG to the brake booster directly for a better response, and run the BOV to the FPR, or vice versa like me.

A MBC will help the turbo spool sooner, but I don't think it'll hold boost to redline with it. The 15G is good to 6k before it dies off, I know this well. Look up my powerband vs. shift point thread.

Drew Peacock

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by BauleyCivic &raquo;</TD></TR><TR><TD CLASS="quote">Similar thread:
https://honda-tech.com/zerothread?id=849644


I'm having the infamous problem with losing boost with the greddy kit. Turbo is a 15g TD04H w/ internal wastegate. I have the vacuum line for the wastegate T'd into the FPR, and the BOV T'd into the PCV valve. The nipple on the compressor housing is capped off.

The turbo spools to .35 bar at around 5000 RPM, and then steadily drops to .27-.29 bar by redline. I'm wondering if a MBC will fix this, because the car has absolutely no top end. Any ideas welcome!</TD></TR></TABLE> Fairly standard practice all the turbos I have had with various configurations have reached full boost then drops back a pound or so. A EBC will help but its probably not worth worrying about . Turn up the boost.

Go Fast Civic

bump.... not really sure either

slow fkn hatch

what a cute widdle turbo.

BauleyCivic

Bump...

tgreaves

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by J. Davis &raquo;</TD></TR><TR><TD CLASS="quote">Sounds like the wastegate opens, then sticks open.

Check for binding in the wastegate actuator linkage, and you might have to tear everything off to see how the wastegate flapper seats. If you've clocked the turbo at a bad angle, it can cause the actuator arm/linkage to bind.

</TD></TR></TABLE>

How would that make it underboost then.. If the wastegate arm is opening and gets stuck as it opens then you would overboost since the wastegate cant open more to divert the exhaust gas as more comes out of the engine..

wantboost

iTrader: (2)

if the wastegate arm is opening all the way and sticking open, as he suggested, then how would it overboost?? It would bleed it off, not build it up

BauleyCivic

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by wantboost &raquo;</TD></TR><TR><TD CLASS="quote">if the wastegate arm is opening all the way and sticking open, as he suggested, then how would it overboost?? It would bleed it off, not build it up</TD></TR></TABLE>

Because as the turbo spools more, the wastegate arm opens more (to keep the boost at the desired psi. If it was getting stuck in any way, it would boost too much, the wastegate opens, and opens too much when the revs go up.

tgreaves

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by BauleyCivic &raquo;</TD></TR><TR><TD CLASS="quote">

Because as the turbo spools more, the wastegate arm opens more (to keep the boost at the desired psi. If it was getting stuck in any way, it would boost too much, the wastegate opens, and opens too much when the revs go up.</TD></TR></TABLE>

Bingo...

wantboost

iTrader: (2)

if it opens too much then boost is bled off, not made. it's a problem with not making enough boost, not making too much.

tgreaves

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by wantboost &raquo;</TD></TR><TR><TD CLASS="quote">if it opens too much then boost is bled off, not made. it's a problem with not making enough boost, not making too much.</TD></TR></TABLE>

Right but if it was getting stuck open then it would spool slower and wouldnt get to the correct boost/or take longer to get there... Its getting to the correct boost and then falling off.. There isnt a way for a stuck wastegate to do this..

BauleyCivic

No, the wastegate is opening more than it should in the upper rpm's...its not getting stuck anywhere

tgreaves

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by BauleyCivic &raquo;</TD></TR><TR><TD CLASS="quote">No, the wastegate is opening more than it should in the upper rpm's...its not getting stuck anywhere</TD></TR></TABLE>

Correct, If it wasnt doing this you would overboost..

If it was hanging open then you would boost very slowly if at all..

Go Fast Civic

i highly doubt that its any of his vac lines because i have mine setup pretty much the same way he does....and mine holds steady all the way till redline

Joseph Davis

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by BauleyCivic &raquo;</TD></TR><TR><TD CLASS="quote">No, the wastegate is opening more than it should in the upper rpm's...its not getting stuck anywhere</TD></TR></TABLE>

Correction - your wastegate actuator/linkage is binding, sticking. I assure you my first surmise is your problem - I've been through it with SOHC Greddy kits before, it is a common problem.

It's not a "stuck so bad I need a 1500 ft/lb impact gun to remove it" stuck. It's stuck/binding just enough that the hot, pressurized exhaust gas escaping the wastegate aperture won't allow it to close... let off the gas pedal and the spring pressure from the actuator is enough to pull the wastegate flapper closed again.

Like I said:<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by J. Davis &raquo;</TD></TR><TR><TD CLASS="quote">Check for binding in the wastegate actuator linkage</TD></TR></TABLE>

I've been through this, and then been through it somemore. I have everyone locally bring their cars to me, I have people drive five hours to have me touch their car, and I wasn't exactly a poor diagnostician before HT heard of my name. When the wastegate actuator binds just so, it sticks open until you get your foot off the damn gas. Seen it before...

BauleyCivic

I get what you're saying...correct me if i'm wrong.

When the engine reaches higher revs, the wastegate flapper opens more (the engine is flowing more air, the wastegate must vent more air to keep the psi in the charge pipes the same).

Now, if it was binding as you say, getting stuck as the revs go higher, wouldn't it boost more? Because to decrease boost the wastegate must open more.

ATS*Mark

i have this problem still.... i cant get my tdo4h to hold steady boost at all , it always falls off...... i think the internal wastegate might be the problem....also make sure all your bolts are tightened on your dp , and everything like that . making a pressure tester and checking to make sure you have no leaks is a good idea too.

Jim Truett

What exhaust are you running? I had this problem with my setup before I went 2 1/2" turbo-back. I assumed it was backpressure slowing down the turbine.

BauleyCivic

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Jim Truett &raquo;</TD></TR><TR><TD CLASS="quote">What exhaust are you running? I had this problem with my setup before I went 2 1/2" turbo-back. I assumed it was backpressure slowing down the turbine.</TD></TR></TABLE>

Still running the stock exhaust...upgrading to a 2.5" soon

Jim Truett

I went from stock LX cat and piping to full 2 1/2" with a Magnaflow high-flow cat and Magnaflow muffler. No resonator was needed, as the turbo quiets the exhaust significantly. I gained a full 1 psi extra boost as well as decreased spool time. The difference was amazing. It didn't even feel like the same car.

Is it possible for you to run it open downpipe to see if your problem persists?

Drew Peacock

Once again this just typical behavoiur from a internaly gated waste gate. Now if you couldn't raise the boost using a boost controller of some kind you would have problems as it is you don't.

boostincoupe

Well ****, I didn't know you were running stock exhaust.

Run open downpipe and let us know what happens.

BauleyCivic

Will do...i'll get back to you folks