JohnRoly

Hello again all,

Am having real problems with the black beasty at the moment and was hoping someone may have some ideas. Two weeks after I got her (95 WRX Wagon import), she started playing up by overboosting in 3rd, 4th and 5th gears - doesn't happen with gentle progrssive acceleration, but if you push her hard, the boost just cuts out at about 1bar and throws you forward. If you keep the loud pedal pressed she will do this 3-4 times in each gear. Scoobysport thought it was the boost solenoid, and cleaned it through for me - no improvement. They then said that i needed a replacement solenoid, which they fitted (after waiting 3 weeks for it to arrive!!) and still no good. Now they say that it is a tiny little valve in one of the pipes - I am doubting if this will fix the problem (but i could be proved wrong!!). So far this little hiccup has costs me a small fortune and has still not been solved.

Please, please help!! Has anyone experienced anythimg similar? Any ideas would be greatfully received (although i cannot promise a cash incentive!!)

Thank you in advance!

The_Judge

Indeed, the restrictor may well be the culprit. In the pipe between your compressor and wastegate actuator, just before the T-piece, is a very small brown "thing" with a tiny hole (about 1mm diameter). If this hole gets clogged up, the pressure on the wastegate actuator isn't what it should be for the boost, meaning the wastegate will remain shut for longer, and bang, you hit fuel cut. So yes, in theory, it's viable that that is the problem, and Scoobysport aren't taking the ****.

It's quite possible an over-filled oil change could be the cause. The oil gets "breathed" into the pipes, and over time clogs them up and jams your boost solenoid. I'm surprised Scoobysport didn't check your restrictor whilst waiting the 3 weeks for the replacement solenoid to arrive...

JohnRoly

Thanks 'The Judge' for putting my fears to rest (for the time being, anyway!!). I wasn't suggesting that Scoobysport were being anything but professional, I have utmost respect for them and their staff (and exhausts - yum!!), and i realise fault finding on a complex engine is largely trial and error (might have been nice if they had checked the cheap part before replacing the expensive one though!!!).

I hope this does solve my problems and I will be able to remove the pillow from my steering wheel without further injury. i will keep you posted.

Thanks again

The_Judge

JohnRoly

Been back to scoobysport, had the new restrictor fitted - no change, still getting the whiplash effect on heavy boost. They have performed a pressure test, and now think it is the wastegate diaphragm that is shot. Looks like another £160 to replace!!
Anybody else had this go (they said it was very rare). The cost of sorting this problem out is escalating rapidly - anybody got any other ideas...PLEASE!!!

StickyMicky

try fitting a manuel boost controler?

Peanuts

iTrader: (15)

agreed, get a dawes device for about £35 second hand from the for sale section.
take the ecu and solenoid out of the equation and control the boost yourself

zhastaph

A cheaper solution would be to just clamp off the hose to the duty solenoid then, this will affectively take the ecu/boost solenoid totally out of the equation and leave only the wastegate to control boost, which means if it's working then it should regulate boost at ~7 psi and if it aint, then it will over boost still.

I'm assuming that they've checked that the wastegate isn't totally seized shut by moving it by hand?

muly

Johnroly- have you checked the pressure exchange solinoid ( it has a pipe going from that to the map sensor) as my mate had the same prob as you and changed the things you did and it was the exchange solinoid, sweet as a nut now

JohnRoly

Will a manual boost controller totally override the fuel cut/overboost safety measures?? Bit worried that I will have the boost turned up too high and knacker the turbo!! The wastegate isn't totally siezed, but is leaking pressure (I am quoting here, as I have only owned a scoob for a short period!). I had a similar problem on a previous turbocharged car that was caused by a collapsing intake hose (car was chipped and OEM hose couldn't take the hike in pressure), but cannot see this in effect unless on a rolling road (or by a brave mate hanging on for dear life!!). It is hard to reproduce the problem in anything lower than 3rd gear (although it has happened in 2nd a couple of times with right foot planted).

it is just annoying having to watch the boost gauge whilst driving!! Cannot get above 1psi without the problem occuring.

Sorry if i am notmaking any sense, but just got back from a business lunch - hic!

zhastaph

No, the safety measure you are experiencing is fuel cut, which is exactly that. What the boost solenoid actually does is introduce a leak in the pipes feeding boost pressure to the wastegate. If pressure is reduced at the wastegate then it wont open. This leak is finely controlled by the ECU so that the wastegate opens at the ECU's target boost pressure, not the boost pressure of the wastegate which is about 7psi.

By removing the boost solenoid, either by clamping it's hose, or by even removing the electric terminals to it, then this will totally leave the control of boost down to the waste actuator. If this works then boost will peak at 7psi (or thereabouts), if it doesn't then you will still have the same problem you currently have.

leeps

Hi John Roly
I also had a boost controll problem a while back and thank goodness touch wood it hasn't come back. It is quite a common problem so i don't know if you did a search or is search even working .. (sheesh ive been gone a while)

If you can do a search go lookup my name and subject under overboosting but not maf. Im not quite sure that your car would be experiencing a fuel cut at 1 bar. How do you know it is one bar? Do you have a boost gauge? and if so is it accurate?

If it is then it could be a number of problems. If it was the coil pack or spark plugs it is quite a noticible noise and jerk. Can't explain that !! So u can check all the usual culprits which is what i did ... oil, leaky pipes, boost solenoid dirty,
mine was believe it or not the pipe from my dumpvalve .... still not sure why ..

Anyways however if scoobysport think the wastgate is shot then I think you already have your answer ... Just here to give my 2 cents worth

leeps

The_Judge

Indeed, and the answer is there's probably nothing wrong with that either...

zhastaph

The only thing that bothers me about the whole of this is that he says fuel cut is kicking in at 1 bar. The ECU will fuel cut at about 1.3 bar

This almost implies that the ECU thinks the boost is 1.3 bar when it is actually 1 bar, MAP sensor

JohnRoly

I do have a boost gauge fitted, not sure if it is accurate as it was fitted in Japan and I am a total dullard when it comes to things such as this!! It is the fact that the fuel cut keeps cutting in and out out under hard acceleration in each gear, i.e. if I keep my foot planted, the turbo will spool then cut and repeat 3 or 4 times in close succession. Really does feel like something is wrong!! What bothers me the most is that it happens far more frequently in higher gears, and never in 1st and almost never in 2nd?? I am going to take it to an independent scooby trained mechanic who is a friend of a friend and see what he thinks - I have lost patience (and a lot of money!) with scoobysport - although I still like their exhausts!!

JohnRoly

Thanks leeps, but cannot seem to search anymore (which is a real pain in the a**e!)

STi Blues

JohnRoly - I have just posted regarding overboost as well - my WRX sti MY97 was spiking to around 1.5bar before hitting fuel cut. PE had a look at it and have now steadied to around 1 bar - at least I can put the hammer down in all gears and it wont hit cut - before they did this I hated driving the car - it was dangerous to be honest.
There guys told me that it was a common problem with imports (especially pre 98) especially when decats, etc had been addeed. They said the mods are done and the car can run fine for ages and then suddenly it starts boost spiking and stuff. I am going back to PE next week - a bost controller seems the most likely fix. I'll let you know how I get on - having the car running 1 bar without spiking has been infinitely better than having it spiking all of the time - expecially when overtaking?

The_Judge

You wouldn't expect it to occur in lower gears, as the engine doesn't produce as much exhaust gas, so the turbo doesn't spin as fast, the compressor doesn't compress as much, there's less manifold air pressure, and so less fuel is required, and therefore no fuel-cut...

JohnRoly

Good point Judge!!
Sti Blues, sorry to hear ypu have been having the same probs, you are right about it being dangerous and making you hate the car!! It was only after I had the car about two weeks that it started happening, been modding since then but has not made the problem much worse. Want to try and fit a scoobyecu to see if this corrects the problem, as it will raise the fuel cut levels - but cannot get one for love nor money at the moment. If not then it looks like I will be going down the boost controller route as well!!

muly

Johnroly- did you try the exchange solinoid as they get blocked aswell, it gives the same symtoms as the boost solinoid, pics can be found on Derick site http://www.derekcarswell.co.uk/

wigan wayne

John

Interesting reading your thread, and hope it gets sorted soon.
What fuel and octane booster are you using?
I only ask as I got some bad Optimax fuel 2 weeks agoing and
the car started overboosting. Took it steady, filled up again
and used 1 millers and car back to normal- strange.
It looks like the low octane was causing the car to fuel cut-stop det.

WW

JohnRoly

Thanks Muly, couldn't see the exchange solenoid in the photos, but probably because i would need a big arrow pointing to it labelled "EXCHANGE SOLENOID"!! (I will learn my way round this engine - just takes time!!). I have only ever used Optimax (but no Octance Booster). Reset the ECU when i picked her up and ran her in on Optimax to minimise any problems - 2 weeks later and problems arose!!

wigan wayne

John

If Your car is an Import without any remap for Uk fuel, then
the car will never run correctly.
It is constantly ratarding the ignition to cope with the low octane,
imagine if you get a bad batch like mine and don't have booster
in - Bang!!
If your not using booster and don't have a Knock link or similar
your car will be very close to the edge. The fuel cut is saving your
engine.Every time you boot it- the car will be knocking, ecu trys
to cope, cuts boost etc etc etc.
Octane booster is a must and the difference in performance and
running is very noticable. Like I said mine is always run with it and
when not it has problems. Try running it with OB and optimax close to
100ron you never know it could be as simple as that? was for me.

WW

JohnRoly

WW,

I will certainly give it a try, what OB do you recommend?? Seems like most people are using Millers, can you get this in places like Halfords??

Sounds like i need to get a scoobyecu pretty damn quick for the UK fuel map if nothing else!! Anyone know who has them for sale??

Thanks again

STi Blues

Wigan Wayne - gald to hear the Optimax + OB worked for you - my problem was made no better or no worse when using OB - I still use Optimax + OB to be safe though.
I am more confident now that the spiking has stopped, but need to run more boost - at the moment I have got worlds most expensive mondeo (or that's sometimes what it feels like when I am a bit down about things - after all classic or not the Sti is supposed to be quick!)

wigan wayne

John
I use millers but have used Pro boost in the past, found the millers
to give best effects

You can get it from many places, try typing Millers octane
into a search engine like google - loads have it.

I get mine from DP motorsport in warrington.

Best to reset ECU then it will set all limits etc back to factory
and make full use of the extra octane.

WW

JohnRoly

Cheers WW,

If that is the cause of all my problems, i will be giving myself a very hard kick in the ***** for being such an a**e!!

bondytheboy

have you checked all the small pipework to the boost valve had the same trouble turned out to be a split hose hope this helps

JohnRoly

Hiya bondytheboy, there was a split hose, this is the first repair I made sometime ago hoping it would solve the problem, but no luck - will have to see what the mechanic finds on sunday (fingers crossed!)

Cheers

Roly

torment

JOHN...Some weeks ago,I was in talks with a scooby specialist,Getting some parts prices..And mentioned just this problem the early cars had...He said that the classic cars had a e.c.u glitch that causes this happening...And is quite normal....He also stated...The only way to erradicate it ..Was to upgrade the ecu itself....So perhaps...This will save you spending even more money to no avail...?????So perhaps he may be correct...????....
Just a thought....Kev.