Chris.Palmer

paulwadams_my99 - its a pre MY 97 - these have 3 port solenoids.

The restricor is the bleed pipe between solenoid & airbox - just check its not clogged - I wouldn't recommend changing the size though.

[Edited by Chris.Palmer - 9/4/2002 8:25:33 AM]

paulwadams_my99

so what does the restrictor do on a 95 different to a 99? Presumeably its in the position of it. On the newer cars on the right hand side on turbo out before the t piece to the solenoid. On the later cars in the pipe to the solenoid??

Surely its there to achieve the same objective albeit in a different place and as you say increasing or decreasing the size of the hole affects the boost. Hence clogged up etc. Im thinking out loud, if its blocked up in the pipe to the solenoid and there is full restriction basically blanking it off wouldnt that lead to less boost as the wastegate opens quicker and at actuator pressure due to the boost not being bled away??

Sorry for the hijack

Cheers

Paul.




Edited cos i just re-read what you said paul and that is what i was thinking out loud. Well I still cant see the harm in looking into the restrictor size myself but might as well change all the pipes first to elliminate a holes/splits as Chris says, if you havent already.

[Edited by paulwadams_my99 - 9/4/2002 2:14:44 PM]

shiper

On my95 wagon when accelerating hard the boost goes straight up to 15 psi for a split second then drops to 11 psi and steadies off then back up to 15psi when you change again and then back down to 11psi. I've been on the forum with problem before and checked every thing and haven't solved anything.Its got full s/s exhaust without cat and panel filter upgraid. Subaru garage don't know and don't seem interested. I've put in new plugs and just had 90k service inc. belt ect.The acceleration isn't smooth and sometimes in first gear the engine just cuts out for a split second around the 4000rpm mark asif petrol has deen cut.
Any ideas???

nom

Sounds suspiciously like overboost. Presumably because of the decat.
A fix would be sticking a Dawes in (and a boost gauge to check setting) and limiting the boost to whatever 95 WRXs are meant to be at . This would likely have better boost control than your current system.

shiper

Hi m8. It seamed to do the same before the decat was fitted and its a uk car so should the boost go up and down or just stay at a strong even boost???What boost should it be (@14psi constant?)

dowser

While the Dawes may (probably will ) fix it, better to fix the cause before adding further mods really. Do a search on solenoid cleaning, and don't forget all the pipes.

Richard

shiper

I've cleaned my solinoid and all the pipes with brake cleaner and this did help a bit but the problem still persists. Oil level is ok.???

nom

Oops - misread a bit of detail
Don't know what the boost should be - although I think it's 0.9bar? (13.5psi) - I'd go on someone else's guess though - but what the boost should do is scoot up to 13.5 & sit there, possibly until high rpm & drop (dunno there - depends on the mapping). This waving about is wrong though. A bit of a peak could be considered good (so go to 14 then within a second drop to 13-13.5) but that's about it.
If everything else is 'clear' & it did it before the decat, I'm not sure what could be up. It's not like the ECU leaving the wastegate to its own devices to reduce det, as can & does happen, - it simply shouldn't be fluctuating. So the Dawes, set up sensibly, should not cause any further problems and should remove the current one.
Hopefully

shiper

Cheers. Do you know how much a dawes is and how and where to fit them. Is it difficult or should i take it to a garage.I'm hoping to go over to well lane turbo centre but want to fix problem first.

Chris.Palmer

Max Boost Target for a UK is 11.47 psi - Fuel cut is 14.8 psi held for about 4 secs.

What I think you are experiencing is boost overshoot - & then sometimes fuel cut.

Overshoot is caused by the solenoid not being able to bleed off enough air quickly enough - hence it overshoots the target psi.

Suggest you take off the bleed hose - goes from solenoid to air box - and clean very thoroughly - there is a restricor in this pipe at the solenoid end & this can get partly clogged.

Hope that helps.

Let us know how you get on.

[Edited to add]

Could also be caused by a tiny pressure leak - in any of the pipes between the turbo & wastegate actuator (via solenoid) - however - this is more likely to exhibit boost oscillation ie 15 - 11 - 15 -11 etc as more air is bleed away than the ECU thinks it is & then solenoid duty cycle is adjusted and over compensates.

Check all hose for leaks & ensure all connections are tight.


[Edited by Chris.Palmer - 9/3/2002 8:41:50 AM]

Stephen Cole

I get the same thing
When first accelerating hard (and it has to be 100% throttle usage, anything less and it doesn't use maximium boost)
the boost shoots up to about 13psi (peak boost) and then after about half to one second drops back to, and stays at, 11 psi (sustained boost)
Well, stays there for a few seconds till you either back off or change up or run out of road or decide you are going too fast and risking your license !
If change up eg to 5th and continue to accelerate hard, it does the same thing with high initial peak bost dropping back to the slightly lower sustained level

Or maybe I've got these terms (as used on the rolling road runs) confused

Wish I could keep my sustained boost at the peak level !

Really aught to go to a dawes, and will do if/when my insurance allows mods

NB This is all with the standard boost solenoid, and is probably caused by the initial boost going up faster than the solenoid can react and bleed it off

In my experiments with bleed values, I could increase the initial peak boost (until it hit overboost), but the sustained level would always drop back to the same 11psi

Stephen
WRX MY-94 5 door standard 220PS 11psi
(5 door has the smaller TD04 Turbo)

Chris.Palmer

Stephen,

2 psi overshoot to peak at 13 psi & drop back to 11 psi sounds normal.

overshoot to 15 psi is a bit excessive - especially if you're getting fuel cut.

PS - Knew some early WRX & STIs had different turbos to UK (were they VFs or IFs? - I can't remember) but I didn't think the Pre 97 had a TD04 - Thought that was standard on later UKs?


[Edited by Chris.Palmer - 9/3/2002 6:16:30 PM]

shiper

I've taken off the pipe from the solinoid and cleaned it well with brake cleaner and it is still doeing the same.
I'm fed up now i've tried everything so i have booked it into well lane for saturday.I'll let you know what they say and do.
Thanks for the responce.

Chris.Palmer

A Dawes will remove the current problem (hide the root cause though) - give better spool - and the option to increase boost - if they can't fix it you could use this as a "Plan B"

The only other option is a dodgy solenoid - but generally they seem to be quite reliable - so I think this is unlikely.

If all pipes are clean - my money is on a teeny tiny leak - but thats a bugger to trace


Please gives us an update on your progress.

I really hope you get it sorted - I've suffered these problems (albeit of my own making ) and they can be really frustrating.

Best of luck m8.

Chris

paulwadams_my99

If you have cleaned everything i suspect this is more to do with the size of the hole in the restrictor. This is in place between the turbo out and the wastegate. Because the boost is building up so quick the 2 port solenoid cant bleed the boost/control it quick enough. Increasing the size of the hole in the restrictor should lead to a bit better boost control as the solenoid can start bleeding it earlier/steadier. Or you could use a mbc as ppl have said but then you take away the function of the solenoid which may reduce boost at times of det etc.

shiper

Still not sure where the restrictor is. Please have you got more infomation as to where and how big it needs increasing to.

paulwadams_my99

Chris,

Why do you not recommend changing the restrictor? It’s not a particularly dangerous thing to do. I had to change mine when i had a dp etc done because boost targets were being reached so quick that i experienced the same symptoms. Obviously this is based on a newer model but to me it seems that the general design of controlling boost isn’t particularly clever. Subaru just try aiding the control with a restrictor based on the deficiencies of the solenoid??? One of my reasons for moving to the link was the the new 3 port solenoid removing the restrictor altogether. Which makes me wonder why an early 3 port has a restrictor at all??? I thought the point of the 3 port was to do what the restrictor did inside the solenoid? Or is the solenoid once again built in such a way that it still needs a restrictor to allow it to cope?

Cheers

Paul.

Pavlo

because on a 95 car, the restrictor does a different job, and a blocked on would tend to reduce boost. so it probably isn't blocked.

I see 14psi overboosts at times if running standard ecu with decat downpipe.

cleaning everything though is probably a good idea.

paul

shiper

I've checked all the pipes and can't find any holes ect and now i haven't a clue what to do????
Should i get a dawes?????
should i increase the restrictor from the solinoid????
should i replace all the pipes with silicon hosses????(will this help anyway and where do i get them from)
Or do i wait until i've had a diagnostic check at well lane turbo centre on the rolling road.
Please respond any one who is 100% sure.
CHEERS ALL

Chris.Palmer

Ok - lets go over it again.

Boost peaks at 15 psi (bit high - 13 max I would have thought) for a second or so (or are we talking 4 or 5 seconds?) then drops to 11 psi (which is normal).

If it is peaking at 15 psi "only for a split second or two" - then I think you are UNLIKELY to be experiencing fuel cut - which is the only real issue with high boost (ok det is problem but afr is very high on early models - so unlikely to be an issue).

So if we're only talking "a split second" and your not experiencing fuel cut - then there is no major issue here - so lets not worry about the 15psi temporary peak boost.

If there is no fuel cut this is not a problem.

I hope this is re-assuring - (diagnostics with a select monitor will definitively confirm whether or not you are getting fuel cut - remember 15.48 psi for at least 4 seconds).

I think the *real* issue is the 4000 rpm hesitation in 1st gear. Does this really *only* happen in first gear & at 4000 rpm? Can it be reproduced in other gears or Revs? Does it happen part throttle or only on Full Throttle?

Hesitation below 3k rpm is common on pre my97s due to emmisions mapping etc - "they all do that sir!"

Hesitation full throttle hard acceleration - could be dodgy coil packs.

Sorry for all the questions - and more concerns - but this IS difficult to pinpoint.

Diagnostics on a RR with a Select Monitor will help alot.


In answer you your other questions - IMHO :

A Dawes is likely to fix (hide) your current problem - purely as it cuts out the solenoid and pipework (which is most likely to be at fault) - on the positive side it is cheap, simple to install & has the additional benefit of allowing you to raise the boost (but beware this can be addictive )

Personally - I think playing with restrictor(s) is not a good way to fix the problem - if you "over-cook it" it is very difficult to go back - unless of course you buy a new set of pipes & play with them.

Replace with silicon hoses - good idea however at least two pipes (turbo-solenoid & Solenoid-airbox) have restrictors - the only pipe not to have a restrictor is solenoid-Wastegate actuator.

Chris

shiper

Thanks alot for you time Chris.
The discussion started because i have not got a smooth acceleration through any of the gears and sometimes a get a sudden stop/start when driving hard 'but it has only happened twice and at about 4/5000 rpm.
I was told to fit a boost gauge to see what psi i was getting and the result was when i floor it in any gear for a split second the boost goes upto 14.5 psi then drops sraight away to 11.5 psi.
When accellerating after the boost has droped back down to 11.5 it seems to hesitate and go ,hesitate and go.
It sometimes is allright and sometimes real bad but doesn't make any dif.if its hot or cold, it's very hit and miss.
Would you (if you were me) take it to see what the problem is as i'm not too good at the machanic's or should i try a different aproach?????

shiper

Sorry i forgot to say i have had all the coil packs off and they are alright as they all read @ 1.3 ohm's which i hope is right as i read on a nother thread that it should read 0.8ohm's plus a loss on the cabbles and when i went to the local scooby dealer they said that if the coil pack goes it would pack up completely and only run on 3.

shiper

Hi.I've just been for a 70 mile drive in car and had no problems at all.Boost went upto 14 psi max but only occasionalyand mostly settled at 11.5 psi.Hopfully the grems gone (since i cleaned out the pipe)
Taking it sat anyway and they might pik somthing up.
I'll mail back on Sat. evening and let you all know.

Turbo_Steve

My MY94 does exactly the same in standard trim....peak boost of 14.5(ish) at 4000rpms, then backs off a little. Occaisionally I will get a fuel cut on a really cold day. I just figured the problem will go away when I re-map the ECU. All the standard scoobies I have been in do the same thing: Peak boost at about 4000-4500rpms and then back off a little. You can hear it and feel it. However, friends P1, my old RA and a few others don't cos they have a different set of ECU maps. Get your car re-mapped. You will not regret it anyway, cos your car will use (fractionally) less go juice, feel better to drive, go faster and generally be more wonderful.

Turbo_Steve

My MY94 does exactly the same in standard trim....peak boost of 14.5(ish) at 4000rpms, then backs off a little. Occaisionally I will get a fuel cut on a really cold day. I just figured the problem will go away when I re-map the ECU. All the standard scoobies I have been in do the same thing: Peak boost at about 4000-4500rpms and then back off a little. You can hear it and feel it. However, friends P1, my old RA and a few others don't cos they have a different set of ECU maps. Get your car re-mapped. You will not regret it anyway, cos your car will use (fractionally) less go juice, feel better to drive, go faster and generally be more wonderful.

shiper

I've been to get car sorted by the guys at well lane in Battley and was very impressed.
THEY HAVE DONE IT
It was the Knock sensor on top of the block that was faulty.
They took it off and re earthed it and strapped it to a rubber pipe.
First they tested on the rolling road. It came out at 241bhp and then did the knock sensor. I then drove all the way home @ 70 miles in a car that drove unbelivably smooth and with more power than i've ever had. When i've put on the new sensor i'll take it back for a re run but maybe get it chipped.They fit there chips for 395 + vat. is that a lot or O.K.

Chris.Palmer

Really glad you got it fixed - Knock Sensor ehh - umm would certainly account for boost being prematurely retarded.

What does their kit include for £400? - Just a Fuel cut lifter & a Bleed Valve or is it a "Proper 27c1028 or Daughter board & 27c512" ECU re-map.

If its just Fuel Cut Lifter (or worse Fuel Cut Defender ie no protection) + bleed valve/MBC - suggest steer clear - as you could do it yourself for far less dosh. (My Lifter and MBC stage 2 kit is for sale if you are interested http://www.scoobynet.co.uk/bbs/threa...hreadid=129043)

If its a "proper" chip & re-map do you know what MAPs have been optimised.

Only asking as my DIY remap - run at Tuning Japanese last week - acheived 268BHP & 247lbs ft torque.

See here full full details http://www.saxonfields.freeserve.co.uk

This was accomplished by adjusting following MAPs:
Boost Map
Fuel Cut Map
Boost Solenoid Duty Cycles
Ignition Map
Fuel Map

This will soon be vailable if interested.

Cheers,

Chris

shiper

htl

BruceWarne

I get the idea you guys don't know what the boost control solenoid id for.

It bleeds off air to increase the point at which the wastegate opens ie higher boost.
If it can't bleed off enough air, the wastegate will open sooner, meaning lower boost.

Stephen Cole

Interesting that you've tied in back to the knock sensor as I was about to say the same thing
ie if you start getting either spurious knock or a faulty knock sensor, the advance will back off, and then potentially pick up a good signal again and readvance
All the while holding the steady 11psi or so sustained boost.

I know as I've experinced it
ie accleralate hard and it boosts as expected (peak dropping back to sustained), but sometimes it just feels like it is holding back, and then suddenly it will surge ahead and pull strongly again.
And sometimes the other way ie pulls strongly at first then seems to hold back
All while holding the expected 11psi sustained boost
(ie boost NOT flunctuating, apart from the intial overshoot/peak boost issue)

However I was indeed getting intermittent Check Error 22 (knock sensor) problems at the time, and the light would definitely come on when this holding back and surging forward effect occured

Did you get any check engine light coming on in your case ?

Mine strangely cleared itself up after a while, but has started coming back again, and I'm going to reseat and/or replace the knock sensor

What was the bit you mentioned about strapping it to a rubber pipe...?!?



[Edited by Stephen Cole - 9/11/2002 6:11:48 PM]