johngoulding

iTrader: (7)

cant get boost ? if i undo the battery , reset the ecu i have boost for about an hour at 0.9 bar then it goes back to 0.5 bar ?
i know:
there are no boost leaks
it never overboosts
i have changed maf sensor
spark plugs
coil packs are in good nick ( very)
installed u8 ecu for the td05 (still had problems before this though? )
replaced boost solenoid with 3 different ones?
changed coolant temp sensor and fan switch ?
tried to run manual wastegate boost by hooking up actuator to compressor outlet and shortening rod ( didnt work )
tried bp102 fuel ( 102 octane fuel ) didnt work also
even tried a restrictor pill in the pipe but also didnt work
i have a hks induction kit with standard rec d valve
samco hoses
i have a reciept for a superchip but as i have changed the ecu i think ths makes that null in void now as far as i know they have to be soldered onto the ecu ?
standard fuel pump and injectors
scorpion cat back exhaust stiill have down pipe with cat installed
there is a whit circular connector on the driver side wing next to the boost solenoid that is not connectedto anything.
two wires coming from the wiring harness just underneath thefluid reservoir for brakes and two above it it looks like these are broken ? but dont know if they should be connected together
and i had a code for the 02 sensor a month ago but after ecu reset the code did not come back ?

no fault codes at present ?

car boosts perfect after reset also runs perfect then cuts boost to 0.5 bar after an hours driving ?

car is a 1995 wrx
sorry for the long list but i think its need 2 know stuff ?

uk300scoob

iTrader: (24)

get a manual boost controller and turn boost up to 1 bar and nomore and leave it at that

johngoulding

iTrader: (7)

what if its det thats causing my problem even though im not getting a code for the knock sensor if i use an mbc things could go bad for me ? my spark plugs say that its def not det but u can tell its the ecu thats cutting the boost as it instantly drops from .9 to .5 ? if i disconnect my actuator hose i just overboost obviously so i know its nufin tae do with the turbo or wastegate ? just curious as to which my car thinks obviously that sumfins not right i would like to know what before i bypass the solenoid ?

kevin wrx

iTrader: (1)

standard boost is normally only 7psi as it is on mine as bieng totally standard.sometimes differant air temps cause boost to flactuate.like on a cold day they will boost rerally well but on a very hot day they might be down on boost a little but could be wrong with my theory but only gion by personal experiance.

johngoulding

iTrader: (7)

7psi bar is definately not standard boost pressure ? and id put my sons life of that m8
7psi=0.4bar which is limp mode or safe mode , standard boost on a wrx is between 0.7 and 0.9 bar or 10 to 13.5 psi known fact is i never knew this a few years ago and i thought my car was running normal until i had the fuel pump changed as the car was slightly detonation under load but wasnt noticable so i thought it was running normal?

johngoulding

iTrader: (7)

the only mods i have is an exhaust and air filter really with the u8 ecu thats hardly far from standard without a remap

johngoulding

iTrader: (7)

i canreach 0.8 standard boost even the 3b ecu which is the worst comes with the base model wrx and that standard boost is 11psi ?

johngoulding

iTrader: (7)

problem is when i reset the ecu i get standard 0.8 BOOST after time it sudenly and quickly drops to 0.4-0.5 which is in limp mode teritory and the main question i was askin is that would basically sumfin like a spark plug gap or an 02 sensor cause me this problem ?

Splitpin

Some real b*ll*cks being spoken on this thread - in particular the chap whose idea is to fit a manual boost controller. Talk about treating the symptom rather than curing the problem - wonder if he'll pay for the repairs if this wheeze results in a blown engine?

John - as you say, if the ECU is cutting boost after a duration of driving subsequent to a reset, there's obviously a reason why this is happening. Obvious question would be, as you've already asked, whether there's any knock happening. Do you have a KnockLink or other method of actually listening to the engine? If not, this would be a good first diagnostic step.

Beyond that, I don't so much have answers, at this stage, as more questions. In particular you say you've changed the ECU "for the TD05". Early WRX saloons had a TD05 as standard, so are you saying you've got a wagon, and changed the turbo and ECU?

As far as Superchips are concerned, I know little specific about early Imprezas, and less again about third party piggyback stuff, but have you actually looked to see if there's anything hooked into your wiring loom? You may well be right about it being soldered into the ECU (have you opened the top to check?) but have you definitively ruled out the alternative?

Before you go any further, getting some confidence on the knock (or otherwise) issue would be the way to go.

will_wrx

Award for the ****test advice goes tooooooooooooooooo..

Lolll

johngoulding

iTrader: (7)

yes i removed the top of the ecu but couldnt find the chip ? going to try and get a select monitor as iv got the parameters written down as to what sensors should be operating at but dont know where i would get a select monitor from in edinburgh ?
ps i dont have the td05 in yet ? didnt think this would be a problem as i feel i should sort out the boost cut before fitting a good working part and also i had this problem wif the 3b and u8 ecu's and good show for knowing its a wagon , got 2 kids and a dog , nice sti setas spoiler etc , spnt too much money on it to spend anymore until i resolve this problem and btw i know my spark gaps are set to 1.1 on 0.9bar of boost and i know this is a little big but the boost cut doesnt always happen when on boost so i thought if it can boost for half a day sometimes then why does it just cut out ? car always idles at 900rpm no fluctuations although i will say that boost feels more powerfull sometimes than others but barely noticeable and im still keen on knwing if my 02 ssensor would cause this boost cut problem as i sed i had a code a while back but stupidly cleared it without checking the sensor as i dont have an asciliscop or whatever its called supposedly u cant test it with a multimeter coz car has 2 be running with sensor plugged in at operating temp ? sorry for long post , habbit

myblackwrx

iTrader: (1)

1.1 imo way too big as it should be about 0.7mm (and i'm running 0.95bar)

White circular connector i think would be the 'Cat on fire' sensor (normally disconnected if a decat has been fitted).

Any subaru dealer/specialist should have a Select Monitor (although a dealer may be funny about dealing with an import).

With the o2 sensor possibly playing up you would get quite poor fuel consumption as it would be running rich

NAY93WRX

iTrader: (3)

Mate,

I had the smae problem on my 93 wrx.

I replaced everything that controlled or did anything with boost ie: ecu, turbo actuator, solonoid, O2 sensor, plugs etc

I cured it by fitting a Polar Performance ECU chip (the best £150 I ever spent on the car) once it was fitted the car was perfect.

Search for "0.5 boost aarrrgghh" on here mate to see my thread

Nay

Glowplug

iTrader: (8)

I would re-fit the OE ECU and gap the plugs to the reccomended 0.7mm.

You will NOT get a fault code for 'det' as there is not one,(hence the use of det cans) you will however get a code for a faulty knock sensor!!

I'm not sure you can simply swap a TD04 mapped ECU with a 05 mapped ECU with the 04 still fitted

Do NOT install a MBC until you have figured/resolved the under lying problem

kevin wrx

iTrader: (1)

ment to say 0.7 sorry to confuse you

johngoulding

iTrader: (7)

gapped plugs to 0.63 as prescribed by far east performance and still no change ? btw i had the problem with both ecus only difference between them is that the u8 holds 0.9 until redline which i go nowhere near anyway and the 3b runs 0.8 until 5000rpm also adjusts injector duty and wastegate duty for higher boost on u8 but as i said still had same problem with standard ecu ? getting right voltage/ohms through the knock sensor injectors , boost solenoid etc so they aint faulty but i suspect its obviously sumfin 2 do with when the cars running ? and i have never ever had a code for the knock ? i did notice today that my egt sensor on the downpipe at the bottom has had the 2 cables cut from it and i dont know where its supposed to connect to ? there is also a white cylindrical connector right next to the boost solenoid that is not connected and i tried a half watt resistor in the connections (resistor mod for egt sensor) to bypass the egt sensor but AT OIL TEMP came up on the dash so obviously this aint the connector for the egt thoughts are i think its the AUTOMATIC TRANSMISION OIL TEMP TOO HIGH WARNING , why the hell would that come up on a manual transmision car ? there is also 2 cables been cut that go to the master cylinder on driver side (uk) i think this is for the fluid level warning light on the dash also ? some ruff as **** knt has had this car in the past imo ? still not changed the front oxy sensor aswell as moneys like a pair of spandex right now as i bought the td05 new maf and idle control valve.
think what the boy sed about the chip could work but i put a working u8 ecu in so if it was my tune or ecu then that would have cured the problem ? also i sed i have a reciept for a superchip @300quid ? its not soldered on to the ecu so where the heck is it as this could go bad and cause this aswell so ive heard but most chips are soldered on ?

jonboy0373

Hi just scanned through the posts here, My 1994 RA boosts at 0.8 bar which i am led to believe is standard on most impreza's. I have a full stainless exhaust and down pipe, with power flow stainless filter. Without any ecu mods etc i would aim for 0.7 - 0.8.

Hope you sort it, John

joz8968

iTrader: (13)

Spot on. 0.79bar lol (11.5psi)

johngoulding

iTrader: (7)

DEJAVU OR WOT boy on this site had EXACT same problem EXACT same car EXACT same year and it was also an import like mine and both wagons and we both have heatshields ratling at the same rpm range , weird or wot? he sed he sorted his by moving his knock sensor ? sounds dodgy but 2 months laterat a bar of boost his car still hasnt blew up ? suggestions ?

Splitpin

Obvious response to that would be to remove or fix the rattling heatshield and see if the problem goes away. If that doesn't help, maybe then consider moving the knock sensor, but if you move it elsewhere on the block, and it is picking up extraneous noise, chances are it'll continue to do so if you bolt it down solid elsewhere. If you move it somewhere it can't detect engine noise properly, you defeat the point of having it, and we're back to the comment about the manual boost controller.

Still think that begging, borrowing or stealing a KnockLink (Phormula etc) would be a good move.

johngoulding

iTrader: (7)

no one up this way i know has one was thinkin about phormula ks3 but dunno how much cost implies was defo wanting a select monitor for my year of car i think its a select monitor 1 the ones with the cartriges ?

ChrisBee

Hi, I have a 1996 STI, exactly the same issue and have replaced all the same parts too..



Should i just try a new knock sensor ? Or maybe install a Walbro Fuel Pump ? I have no Fault codes showing though..

Help !

Also anyone know of a impreza specialist in the South West ? Am in Bath area.