howes124

iTrader: (11)

i own a scooby myself for which i have had issues with in the past, a lad popped round mine with a 1995 wrx asking whey his car is hitting what you all call boost cut??, but when sat with him i noticed it was cutting out at random .5 bar then at 1 bar so on and ran a little uneven in traffic,this one is beyond me please help. ps car is totaly standard.

Jaywalker

sounds like boost cut, i think standard is about .5bar or very very close to that, the fact that its going up to 1.bar on a standard car tells me that maybe the actuator spring is faulty or previous owner has messed about and set the boost to high thats bearing in mind there are no air leaks from the boost pipes, on the other hand running uneven in traffic could also point to leaking boost pipes i think,

i think i read on here some where about checking the actuator spring by connecting a foot pump with a gauge on it to the actuator and seeing what pressure the spring compresses at which will give you boost pressure and also while your there check for holes in the pipes

hope this helps

PeeVee

iTrader: (1)

You are talking rubbish jaywalker.

Boost cut comes in at around 1.2 bar and would never be activated at both 0.5 & 1 bar

0.5 bar boost is not std at all, the car should be running almost double that!!

If you were running 0.5 bar in a scooby then you have got a problem & the ecu would probably be in limp home/safe mode.

howes124

iTrader: (11)

sorry m8 but you are being unfair on someone trying to give me advice, my wrx standard, with u8 ecu would only boost to 0.5bar and that is standard m8.but to top it off you gave no advice

Dasco

iTrader: (3)

i thought standard boost on a uk is 0.9bar or 13psi
limp mode is 0.5bar or 7psi
make sure the tubes with restrictor pill in is the right way round as this will cause this

bigsinky

sorry but 0.5bar is not standard on a wrx. either your boost guage is reading wrong or there is a problem with the ecu. standard boost is between 0.8 and 0.9 bar (12 - 13psi)

Jaywalker

yep your right thats why i said very close to 0.5bar just found the web site heres a quote for the U8 ECU,

"U8, 2C - 1993/1994 WRX – TDO5-11.47PSI (0.8BAR) TO REDLINE -FUELCUT 14.5PSI (1BAR) - 240PS (237BHP)"

PeeVee boost cut is not 1.2bar its 1.bar

PeeVee the car should not be running double that it should be running 0.8bar

so PeeVee it appears we are both talking rubbish

so if you wish to correct some one in the future at least get your facts right

this is the reason for forums so if we do make mistakes we can be corrected theres no need for the harshness

sorry howes124 heres a link for the ECU's and there info

Impreza WRX/STi ECU Info - JDMVIP Forums JDM Japanese Cars Import Used Auctions

TonyBurns

iTrader: (3)

.5 bar is limp mode, there is definately something wrong, either boost leak or something more sinister, this is where a dealer/speciallist comes in or it could be an expensive learning curve....

Tony

howes124

iTrader: (11)

he has chucked money at main dealers for fault code reads ect, told him should have come to me earlier done for nothing, they tell him acuator?, or maf this is only fault code i could find.will lend him my maf and go from they.

johngoulding

iTrader: (7)

get ur facts right mate fuel cut comes in at 1.2 not boost cut ???
boost cut can come in at any time and is caused by the ecu gaining the wrong feedback from various sensors , the knock sensor being the most prone due to engine knock the boost can be cut and a LOT of other problems ?

i think u would know what fuel cut is as its like hitting a parked car doing say 10mph its a sudden jolt where the engine doesnt recieve fuel , boost cut is more when ur at full boost and u suddenly feel the car accelarating veryu very slowly like an n/a car rather than running boost

johngoulding

iTrader: (7)

the boost solenoid being hooked up the wrong way can cause your car to run uneven and boost at 0.5 bar it would in efect be the same as hosing from the turbo housing straight to the actuator , u would only run what they call actuator pressure which on a td04 and td05 is 0.5 bar , when the car goes into limp mode it ads or limits the fueling depending on conditions and renders the boost solenoid innefective and allows air to pass straight through the solenoid from the turbo housing to the actuator , instead of opening and closing the valve inside the solenoid to limit the amount of air the actuator recieves , if u disconect the hose from the actuator and drive the car it should overboost , if it does then your car is in limp mode or ur solenoid is wired up wrong or not working ???

howes124

iTrader: (11)

this what we have tried my maf sensor, and also had spare chipped u8 ecu set to 1.14 bar, checked all pipes, cleaned soleinod, with my ecu and his is now hitting a wall at 5000rpm boosting way over 1.1 bar, traffic driving is fine. ????????????

TonyBurns

iTrader: (3)

Get him to take it to someone who knows these cars, we can be at this all day, it probably needs a damn good service and chances are the boost solenoid is clogged or a pipe could be split, tell the people who service the car this and they can look for it, saves plenty of time, hassle and extra cash on things you didnt need to replace in the first place

Tony

howes124

iTrader: (11)

cheers for advice and they was me thinking it would be simply , we have a motorsport place near me told him to take it they tomorrow.

scoobjam74

iTrader: (11)

fuel pump prob maybe as i had running probs a while ago somtimes running fine just driving i found when i accelerated say in second on a flst road steady accelerating revs up to about 4-5 thouh so quite high and smooth in 2nd then boot it it would cut for a second i had had probs with coil packs previously so they were new but found my pump was knackerd i fitted a walbro problem solved , this is on a uk spec 96 running a full decat and hks filter running at 267 bhp this is just a thought and somthing to elimenate from you problem as its quite simple to check

TonyBurns

iTrader: (3)

Sounds like you have an ESL chip or aftermarket ecu too

Tony

howes124

iTrader: (11)

cheers m8 i know he had full service not so long back, and i supplied him with a brand new walbro 255 fuel pump,.

johngoulding

iTrader: (7)

if the solenoid is clogged with crap then it would overboost , it would have to be jammed open or plumbed up wrong to drop boost