Boost Creep

[Ultimategtr]

Hi all.

R33-25t mods:

FMIC

Apexi pod with CAI

Full 3inch exh(no cat)

Splitfire coils

NGK copper .8mm HR7 plugs

Fully serviced - oil filter etc

Atomic boost tap

Alright, so before i used the factory solenoid earthed and got up to 13psi by the redline or so.. now with the Atomic boost tap(set to 7psi) it holds 7psi till about maybe 5k, then gradually increases to around 12-13psi by the redline, in any gear.... i hardly let it near the redline anyway.

i want this issue fixed.. any ideas how to? its a bit annoying at times.

[**RB2530**]

Hi all.

R33-25t mods:

FMIC

Apexi pod with CAI

Full 3inch exh(no cat)

Splitfire coils

NGK copper .8mm HR7 plugs

Fully serviced - oil filter etc

Atomic boost tap

Alright, so before i used the factory solenoid earthed and got up to 13psi by the redline or so.. now with the Atomic boost tap(set to 7psi) it holds 7psi till about maybe 5k, then gradually increases to around 12-13psi by the redline, in any gear.... i hardly let it near the redline anyway.

i want this issue fixed.. any ideas how to? its a bit annoying at times.

By the sounds of it you had a boost creep issue even before you fitted the Atomic boost tap (what ever that is..never heard of one)...Earthing the factory solenoid should get a constant 7-10 psi depending on mods..exhaust, intake filter etc...

Fitting the boost tap (I assume this is just a bleed valve) will not fix boost creep...It can only make it worse..

Most common reason for boost creep is waste gate too small or restricted or waste gate not able to open fully...If you are using an internal gate check the actuator linkage and make sure it is not fouling on anything...

What I suggest is take off the bleed valve and unearth the soleniod so that you get minimum boost...then find out why the boost is spiking (check actuator). Fix this and only then play with the bleed valve...

[justin911]

i had one of those atomic bleed valves, there pieces of crap i sold mine after like 2 weeks.

get one of these

http://cgi.ebay.com.au/Turbotech-manual-tu...1QQcmdZViewItem

there was a 10000 page thread about them at one stage on sau, there good

[Ultimategtr]

RB2530 - thanks for that.. yes it was spiking even before i put the tap on.. when i had the facotry solenoid on there, even unearthed, it would spike up to like 14-15psi. Then i took the solenoid off, and hooked up the actuator straight to a pressure source, and got about 5psi, however that too would spike to about 14psi by the redline(in any gear)

the atomic tap(set to 7psi) has improved it but it still spikes. but only to 12psi or so.

iv got my guess on the actuator but im not exactly sure how to test it.. i was under the impression that i pull the actuator open and go for a lil spin(it shouldnt build boost at all).. and then what? what doe that proove??

EDIT - Justin911 - thanks for that i have just purchased that thru ebat! cos me $47 NZD so hopefully gets delivered to me by this week or next.

Edited March 25, 2008 by Ultimategtr

[**RB2530**]

RB2530 - thanks for that.. yes it was spiking even before i put the tap on.. when i had the facotry solenoid on there, even unearthed, it would spike up to like 14-15psi. Then i took the solenoid off, and hooked up the actuator straight to a pressure source, and got about 5psi, however that too would spike to about 14psi by the redline(in any gear)

the atomic tap(set to 7psi) has improved it but it still spikes. but only to 12psi or so.

iv got my guess on the actuator but im not exactly sure how to test it.. i was under the impression that i pull the actuator open and go for a lil spin(it shouldnt build boost at all).. and then what? what doe that proove??

EDIT - Justin911 - thanks for that i have just purchased that thru ebat! cos me $47 NZD so hopefully gets delivered to me by this week or next.

Pull the actuator open as much as you can and make sure the linkage on the flapper shaft rotates at least 60-70deg. I think that is a good start. It may be that the flapper valve is jamming on something when it is trying to open...or there maybe something broken inside the WG actuator that is stopping it from opening...If you have access to compressed air you can try pressurising the WG actuator. Use a tyre valve or something and just give it a little bit of air...DONT GIVE IT 100psi otherwise actuator go boom!!!

If you can get the WG open and wire it open and go for a drive and the turbo makes no or very small boost up to redline you have then proven that:

1. Your setup can flow enough exhaust through the WG to prevent boost spiking

2. The problem is centred around the WG and actuator and not some other bizarre condition elsewhere in the car...

BTW have you done any exhaust mods recently...I have heard of cases of aftermarket dump pipes designed in such a way that the flapper gets caught on a flange.....Also if there is a divider in you dump pipe and the WG flow is blocked for whatever reason it will cause spiking...

Apart from the above I am all out of suggestions..

[Ultimategtr]

hey thanks for that man, really appreciate it. makes sense too. ill have a go at it after work today.

well i have a TOMEI dump pipe(bellmouth design) and a front pipe. the flapper isnt being restricted by the dump pipe at all. i had a split dump pipe before which i thougth was causing the problem, but wasnt.

So if i go out for a spin with the actuator wired open and i dont get any boost, it means the exhaust is up to spec and not too restrictive right? then could it be the actual spring in the actuator? or what could it be?

sorry to ask these questions. i did try searching but the results were immense and i couldnt be bothered sifting through 100's of pages for answers.

[**RB2530**]

hey thanks for that man, really appreciate it. makes sense too. ill have a go at it after work today.

well i have a TOMEI dump pipe(bellmouth design) and a front pipe. the flapper isnt being restricted by the dump pipe at all. i had a split dump pipe before which i thougth was causing the problem, but wasnt.

So if i go out for a spin with the actuator wired open and i dont get any boost, it means the exhaust is up to spec and not too restrictive right? then could it be the actual spring in the actuator? or what could it be?

sorry to ask these questions. i did try searching but the results were immense and i couldnt be bothered sifting through 100's of pages for answers.

It could be that the actuator has a problem where something inside it has broken or come away and is stopping it from opening as much as it should...I haven't heard of this happening before but there is a first time for everything...As I said before if you have compressed air available try pressuring the actuator and see how much it opens...But once again only add 15-20 psi tops otherwise you may blow apart the actuator...

I once modded an external gate so that I could adjust the spring tension..It worked well but when it was wound up the spring would bottom out (fully compress) and this limited the travel of the WG and produced boost spiking...

[Ultimategtr]

hey man, just tried it, i have the heat shield on my factory turbo.. do i need to take the heat shielf off?

with it all connected, i tried nudging it but it wouldnt budge??? should it be something that moves easily, or do i need some actual efford into it? i didnt pull much cos dont want to wreck it.

[**RB2530**]

hey man, just tried it, i have the heat shield on my factory turbo.. do i need to take the heat shielf off?

with it all connected, i tried nudging it but it wouldnt budge??? should it be something that moves easily, or do i need some actual efford into it? i didnt pull much cos dont want to wreck it.

Not sure about the heat shield...Cant remember cause I haven't seen a stocker for quite a while...

The WG linkage will be tight and hard to move if you cant get a decent hold of it..Remember that it operates at 5-10 psi air pressure so a bit of effort will be required...do you have access to compressed air??

[Ultimategtr]

ahh ok thats cool then. i dont have #10 socket here so il have to leave it till the weekend, my dad has all the tools in the world inc compressed air..

ill pull the actuator apart this weekend. thanks for your help paul. much appreciated. ill post up when i have pulled apart the actuator.

[borko08]

i have the same problem...dont know what to do...if it turns out that the actuator is broken or whatever...how much would another one cost me?

[Godzilla32]

You wont be able to move the actuator by hand.. They are quite firm. My advice is the same as was mentioned and just use compressed air to operate the actuator to make sure its working properly. My guess is that you either have a faulty actuator or perhaps a leak in the vacuum signal hose to the actuator. You may be able to find this when you pressurise it with compressed air, if infact there is a leak.

Good luck,

Deren

[borko08]

Hey guys, just incase somebody else has this problem, i spoke to my mechanic and he thinks that because the exhaust is so free flowing and efficient now (no cat and good dump pipe) the wastegate hole is too small to let the air through, thus the boost creep. So he told me that a solution would be porting the wastegate, but the thinks that modyfing a standard turbo is too costly and pointless. He also says that skylines tend to just run rich, so the surge of boost won't actually hurt the engine too much, just will equal in a bit of smoke coming out and risk of R&R happening. He suggests taking it to the dyno and checking the mixtures just to be on the safe side.

I would like to ask how much porting the wastegate would actually cost if anybody knows? And also is it possible to do it yourself.

Also he said that a tune (SAFC) would come in handy just to correct the A/F ratios abit so less damage to engine and better performance.

If porting the wastegate is too $$$ im just going to get a jaycar digital fuel adjuster and run 10psi and fix up the A/F ratios up top so the car runs smoother.

Hope this helps anyone