Rb25 (s2) Boost Spike *yes I Did A Search!*

[toffy]

Ok first of all my mods are : BELL mouth type dump/front pipe, full exh, fmic, iv'e changed the vacuum(/boost) point that the wastegate gets its air from a few times to various different areas , t-piece boost controller (dr drift) , gtr fuel pump, *central 20 ecu + safc when the boost spiking is fixed* and so on . Now iv'e tried different cat converters, exhausts , wastegate actuators , the std dump & front pipes , played with the timing . ive come to the conclusion that the turbo fitted to r33 (s2 by the way) is a piece of crap thats no better than china turbo's . i have the turbo off for the third time at the moment and i can't be f*kd putting it back on unless i know the problem is solved (the car has been sitting for 3 months because i'm sick of it).

ok heres my questions:

1.) Has anyone ever had the same problem using (brand name) bell mouth dump pipe?

2.) Does anyone have a solution for the problem

3.) If i were to put another turbo on it , what would be the closest to stock/handle (make) around the 200rwk mark (must be bolt on) , i know r34/vg30 turbo's are a very slight upgrade but do they have the same problem?

4.) Is there anything i might be missing or any other suggestions you may have?

The reason i'm only looking for ~200rwk is because it's (or was) my daily and i only really wanted to do the basic mods , and keep it drivable for the missus

[Ultimategtr]

Hey man. im in a similar boat. I think its my actuator tho. but it doesnt spike/creep by much.. only 3-4psi if that.

Have you tried a diff boost tap? or an ebc? How bad are the spikes?

When did it start spiking??

[joeyjoejoejuniorshabadoo]

try an ebc...

[MBS206]

Remove the boost controller completely and test. Does boost hold stable?

Is the waste gate flap hitting the dump?

[toffy]

ulimategtr: i'd be happy with only 3-4 psi , i held it out to see if it stabilised at any time but i got to 5.8-6k and it had reached around 16 psi in 3rd and decided to never do that again

joey: yep tried a avcr on it

mbs206: the wastegate is missing the dump , i machined it out a little just to be on the safe side , i've tried running the vacuum line straight to the wastegate (actually thats how it was just before i pulled the turbo off) but it still boost spiked the same

[TAKUSHI]

is the dillemma im having the same as yours?

i just started a post bout a similar prob but dunno if its the same thing as yours

mmm almost wonder if its a knock sensor going on the fritz

if it reads out of line and measures a phantom knock then it might give the ecu a faulty reading

Edited December 14, 2008 by TAKUSHI

[bradsm87]

If it still spikes even with the boost line going straight from the hotpipe to the actuator using a very short piece of hose (the combo least likely to spike), then I would be checking the preload on the wastegate. Sounds like U have too much. If it isn't adjustable, U might need to do some cutting and welding.

Can U blow in the actuator boost line without the actuator leaking? Does the rod go straight out of the actuator (not on an angle)?

[Az_StrYdeR]

Was going to say I have a spare T-boost controller you can lend to test Toffy, but sounds like its something with the wastegate (which you would already have known)

Actually I have a blown turbo if you want to test that actuator off there?

[gotRICE?]

If you have tried everything including going to stock dump pipe etc id say there is an Actuator problem too.

See if you can get another one somewhere.

I tried a million different things to fix my spiking. In the end it was the shit split dump. Gone to an R32 Actuator and wont ever look back.

[toffy]

If it still spikes even with the boost line going straight from the hotpipe to the actuator using a very short piece of hose (the combo least likely to spike), then I would be checking the preload on the wastegate. Sounds like U have too much. If it isn't adjustable, U might need to do some cutting and welding.

Can U blow in the actuator boost line without the actuator leaking? Does the rod go straight out of the actuator (not on an angle)?

where i found it to hold boost (keep a steady boost before spiking) the best was pretty much where the facory outlet would be for the vac, line its a stock turbo on what was a untouched car before i bought it , the rod goes out of the actuator perfectly straight and both actuators iv'e tried held pressure fine (i have a little air pressure thingy that restricts air pressure out of my compressor to 5-15 psi (adjustable , its home made from an old paint gun a tyre pressure guage and stuff i had lying around my work )

Was going to say I have a spare T-boost controller you can lend to test Toffy, but sounds like its something with the wastegate (which you would already have known)

Actually I have a blown turbo if you want to test that actuator off there?

thanks for the offer mate , but i've tried a different actuator already

If you have tried everything including going to stock dump pipe etc id say there is an Actuator problem too.

See if you can get another one somewhere.

I tried a million different things to fix my spiking. In the end it was the shit split dump. Gone to an R32 Actuator and wont ever look back.

i've tried stock dump/front pipe and actuator , stock cat, gutted cat , straight 3in pipe , 3? different positions for the vac line ,different exh (including std) , checked timing , cleaned turbo out with petrol/kero , ebc, t-piece, factory boost control, straight to actuator , 2 diffrent intercoolers (including different piping) and the list goes on im not sure of the fuel pressure but the base fuel pressure is within factory average (it has a walbro fp, i dunno if it should be higher?)

another thing i noticed that i keep forgetting to mention is that it gets full boost from pretty low rpm , im a little vague because its been a while since iv'e driven it , but it was around 1750-2200rpm-ish (in second or third) , it holds it perfect up until just a lil over 4000rpm

Edited December 15, 2008 by toffy