Jump to content
SAU Community

Boost Creep In Upper Rpm

borko08

By borko08,
in Engines & Forced Induction

 Share

Recommended Posts

borko08 Enthusiast

borko08

Posted
Posted

Hey, as mentioned in the title, i get boost creep above 4500ish rpm. I have a stock turbo, split dump pipe (recommended and installed by reputable workshop), gutted cat, and 3inch catback exhaust, FMIC.

At the moment, I'm not running a boost controller. turbo spools up to 7psi, stays there until around 4500 and then keeps spooling to 14-16psi depending on the weather. The problem only really became noticable/annoying when i got the split/dump done and gutted the cat. before that it would only creep to 11-12 (which wasn't a problem as the ecu wudn't shit itself).

I asked a mechanic what it could be, he suggested that the wastgate needed to be ported, and told me that would be costly and wasn't worth the money on a standard turbo.

I did a few searches on sau, saw that a possible cause could be that the wastgate flap was hitting the split/dump pipe, or that it could be the actuator.

In an old post, sydneykid suggested that pulling the actuator arm off would allow you to see if the wastgate is capable of releasing enough gasses to stop the turbo from spooling up too much.

http://www.skylinesaustralia.com/forums/In...ifying+actuator (last page)

I would like to try taking the arm off, but i can only see one place, and im not 100% sure that is where you're supposed to pull it off. If anyone could shed some light on this, it would be great.

Also, in my search i found the 'bodgy wastgate actuator mod'. If it turns out that the acuator isnt letting the flap open enough, could the wastgate actuator mod be used in reverse? to get the opposite effect (i know it would mean the flap is always a little open).

http://www.skylinesaustralia.com/forums/Bo...le+actuator+mod

Anyone got any ideas? I attached a pic of my actuator, I've never seen another r33 one, so I'm not sure whether there is supposed to be a bend in it.

Thanks in advance

post-39297-1220785637_thumb.jpg

Link to comment
https://www.sau.com.au/forums/topic/235113-boost-creep-in-upper-rpm/
Share on other sites
zebra Grand Master

zebra

Posted
Posted

Yet another split dump pipe causing boost creep.

The actuator only detaches from one place (end of the rod where it joins the rectangular arm)

Its not so much a case of the flapper hitting the pipes but rather the exhaust gas not being able to flow enough through a small pipe and then having to re-join the main system which is generally a higher pressure than the wastegate gasses.

borko08 Enthusiast

borko08

Posted
  • Author
Posted
The actuator only detaches from one place (end of the rod where it joins the rectangular arm)

Yeah i thought so. There doesnt seem to be anything really stopping the rod coming off, do you know whether just pulling it off is alright? Also do you think that will properly diagnose the problem?

borko08 Enthusiast

borko08

Posted
  • Author
Posted
Maybe...it will just make the car slow and laggy, but if it still creeps than id say use the dump as a paper weight and get a bell mouthed 3" jobbie

yeah i figure it will make it laggier, but an ebc should help a fair bit (obviously after i reattach the actuator pole and replace/modify it). As for the split/dump pipe, as i said earlier it was recommended by a tuner with a really good reputation, so I dunno, I'm hoping that's not the problem (since i don't really need another paper weight :))

borko08 Enthusiast

borko08

Posted
  • Author
Posted

Ok, so I disconnected the actuator rod, and took it for a spin. Boost obviously comes on late LATE, but still managed to hit around 14/15 psi, so not the actuator that's causing the problems. Now it seems that the wastegate flap got stuck onto something. So I'm gonna have to drop the exhaust and see what the hell is going on in there.

  • 2 weeks later...
l_uk3y Proficient

l_uk3y

Posted
Posted

Hey there. I recently had the same problem which existed after installing a split dump pipe. Ended up going from a manual boost controller to a Blitz EBC. SAME problem. changed back to the Stocky with wires connected to run 5psi only. Still same problem. Turned out i had a leaking exhaust manifold gasket and now that is fixed im running an almost stable 13psi. Even now it is fixed there is still a hint of creep but it is very easily controllable by the ebc.. Just incase it may be worth getting under there and checking that theres no sign of leakage out the exhaust manifold.

Mightn't help in your situation but it may be worth a try.

Luke

sl33py Mentor

sl33py

Posted
Posted

That mechanic who talked about porting the wastegate sounds like he was fobbing u off to the 'too hard basket'. Find a new mechanic who has a clue with actually *diagnosing* problems and gives a cr4p.

217/r33 Community Regular

217/r33

Posted
Posted

Very common problem with the split dumb pipe, I’ve fixed a few rb's with this issue. It’s caused by the gasses being blocked at high RPM where the two pipes meet and get pushed back thru the waste gate pipe so it results in boost spikes. This normally happens with cheap products like jjr and ebay stuff, they are poorly made so the flow is disturbed resulting in flow issues and boost spikes.

How to fix it? Re-attach your stock dump pipe and just buy a front pipe, you will still get the same power gain for your application.

217/r33 Community Regular

217/r33

Posted
Posted
Yet another split dump pipe causing boost creep.

The actuator only detaches from one place (end of the rod where it joins the rectangular arm)

Its not so much a case of the flapper hitting the pipes but rather the exhaust gas not being able to flow enough through a small pipe and then having to re-join the main system which is generally a higher pressure than the wastegate gasses.

+1 :)

Ultimategtr Proficient

Ultimategtr

Posted
Posted

I can solemly say that i was in the same boat.

I had a dyno before and after the split dump was installed, and NO power gains at all, torque, etc, etc everything same, However i was getting a HUGE boost creep, after 4.5k-5k it would spike to around 14-16psi, to which i backed off instantly.

I changed to a TOMEI 1 piece bellmouth design and it made things ALOT better. I had my timing adjusted which made things alot better. Now it only spikes to 9psi or so max, which i figure is ok considering i dont use an ebc yet.

R33 25t manual

fmic,

full zorst with no cats etc

Boost tap set to 5psi(bought off SAU) turbosmart or something. works really well.

copper plugs.

I suggest checking your timing as well as it will play a small part.

  • 3 weeks later...
gotRICE? Veteran

gotRICE?

Posted
Posted

Had the same problem with the same dump pipe.

Just got it back from being modded, and as most others, it was fouling and only opening 3/4 the way, causing the creep.

Had my mate pull it off and play with it. All fine now. I think he cut out the seperator and re-made it. All works perfectly now.

gotRICE? Veteran

gotRICE?

Posted
Posted
i have a genuine hks dump and have had absolutely no issues... they are not all the same...

Clearly not. When your talking big names they arent going to sell you busshit are they?

This is a case of cheap chinese crap. I tried it, FAIL. But with a little mod its perfect. And it cost far far less including the modding than an HKS item.

Dont get me wrong, i love buying the expensive stuff for ease of installation and hassle free driving. But sometimes its not worth it.

IE an HKS Front pipe (to occompany my HKS Exhaust) in stainless it clears the $400 mark. Its half the price of the whole exhaust! And its just a pipe!

Evil Mentor

Evil

Posted
Posted
Clearly not. When your talking big names they arent going to sell you busshit are they?

This is a case of cheap chinese crap. I tried it, FAIL. But with a little mod its perfect. And it cost far far less including the modding than an HKS item.

Dont get me wrong, i love buying the expensive stuff for ease of installation and hassle free driving. But sometimes its not worth it.

IE an HKS Front pipe (to occompany my HKS Exhaust) in stainless it clears the $400 mark. Its half the price of the whole exhaust! And its just a pipe!

while i agree it's not the cheapest option, the time saved in installation, the time saved not having to find a place to mod a cheaper pipe, the time saved not having to wait for it to be altered, the time and petrol saved not having to go to and from a workshop and i'd say that the price of a brand name item isn't all that bad... plus you get every gasket, bolt and nut (although i'm not sure how the chinese pipes are)

  • 3 weeks later...
Ultimategtr Proficient

Ultimategtr

Posted
Posted

Hey, after some research, i think my exhaust is too free flowing. Could it be?

I just have the usual mods - FMIC, CAI, and a FULL exh.

When i say full, i mean it has NO restrictions at all. Tomei dump pipe leading into a Tomei front pipe which leads into a big section that the 5inch muffler attaches to. There are no resonators/cats at all

my boost issues started when i took off the pea shooter, put splitfire coils and changed to the bellmouth dump.

Whats my best option here?

1) Put on a cat?

2) Go for an ebc(that wont FIX the issue)

3) f**ked if i know!

Currently it creeps up to around 9-10psi, but sometimes it spikes to 14-15psi!!! I back off as soon as it goes over 10psi and let it cool down.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing


  • Similar Content

  • Latest Posts

    • Murray_Calavera
      RB25DE NEO with Haltech ECU

      By Murray_Calavera · Posted

      You won't need to do that if your happy to learn to tune it yourself. You 100% do not need to do that. It is not part of the learning process. It's not like driving on track and 'finding the limit by stepping over the limit'. You should not ever accidently blow up an engine and you should have setup the ECU's engine protection to save you from yourself while you are learning anyway. Plenty of us have tuned their own cars, myself included. We still come here for advice/guidance/new ideas etc.  What have you been doing so far to learn how to tune?
    • GTSBoy
      RB25DE NEO with Haltech ECU

      By GTSBoy · Posted

      Put the ECU's MAP line in your mouth. Blow as hard as you can. You should be able to see about 10 kPa, maybe 15 kPa positive pressure. Suck on it. You should be able to generate a decent vacuum to about the same level also. Note that this is only ~2 psi either way. If the MAP is reading -5 psi all the time, ignition on, engine running or not, driving around or not, then it is severely f**ked. Also, you SHOULD NOT BE DRIVING IT WITHOUT A LOAD REFERENCE. You will break the engine. Badly.
    • GTSBoy
      R34 25GT Engine Light 21

      By GTSBoy · Posted

      Could be correct. Meter might be that far out. Compare against a known 5 ohm 1% resistor.
    • Haggerty
      RB25DE NEO with Haltech ECU

      By Haggerty · Posted

      @Murray_Calavera  If I were an expert I wouldn't be in here looking for assistance.  I am extremely computer literate, have above average understanding on how things should be working and how they should tie together.  If I need to go to a professional tuner so be it, but I'd much rather learn and do things myself even if it means looking for some guidance along the way and blowing up a few engines. @GTSBoy  I was hoping it would be as simple as a large vacuum leak somewhere but I'm unable to find anything, all lines seem to be well capped or going where they need to be, and when removed there is vacuum felt on the tube.  It would be odd for the Haltech built in MAP to be faulty, the GTT tune I imported had it enabled from the start, I incorrectly assumed it was reading a signal from the stock MAP, but that doesn't exist.  After running a vacuum hose to the ECU the signal doesn't change more than 0.2 in either direction.   I'll probably upload a video of my settings tomorrow, as it stands I'm able to daily drive, but getting stuttering when giving it gas from idle, so pulling away from lights is a slow process of revving it up and feathering the clutch until its moving, then it will accelerate fine.  It sounds like I need to get to the bottom of the manifold pressure issue, but the ignition timing section is most intimidating to me and will probably let a pro do that part.  Tomorrow I'll try a different vacuum line to T off of, with any luck I selected one that was already bypassed during the DBW swap.  (edit: I went out and did it right now, the line I had chosen did appear to have no vacuum on it, it used to go to the front of the intake, I've now completely blocked that one off at the bracket that holds several vacuum lines by the firewall.  I T'd into the vacuum line that goes from that bracket to the vacuum pump at the front of the car, but no change in the MAP readings).  Using the new vacuum line that has obvious vacuum on the hose, im still only getting readings between -6.0 and -5.2.  I'm wondering why the ECU was detecting -5.3 when nothing was connected to the MAP nipple and ECU MAP selected as the source. @feartherb26  I do have +T in the works but wanted to wait until Spring to start with that swap since this is my good winter AWD vehicle.  When removing the butterfly, did it leave a bunch of holes in the manifold that you needed to plug?  I thought about removing it but assumed it would be a mess.   I notice no difference when capping the vacuum line to it or letting it do its thing.  This whole thing has convinced me to just get a forward facing manifold when the time comes though.
    • CF.Panda
      R34 25GT Engine Light 21

      By CF.Panda · Posted

      Update: tested my spark plugs that are supposed to be 5ohms with a 10% deviation and one gave me a 0 ohms reading and the rest were 3.9ohm<, so one bad and the others on their way out.
×
×
  • Create New...