not boosting correctly

pk4rney

went to see an uk turbo today but it felt like it was holding back on boost especialy in 1 and 2 it felt like no boost and could hardly hear dump valve the dump valve is standard. the turbo spools up and you expect to be stuck to the seat but nothing realy happens. dont get me wrong im still gonna get the car cause the rest is faultless.i thought it might be because of two things vaccum pipe might be loose, or a sensor could be gone, or it might be because ive mostly been in wrx's, but i was in a uk turbo years ago and it pulled nicely ive also had a punto gt and that pulled like a train and that was only running on 3. if anyone has got an idea let me know please thanks

batmanwrx

iv got the same problem with my car i have a oversized up pipe and its notpushing the air frew fast enough,steven

pk4rney

this car is completely standard thou.

batmanwrx

are you 100 %sure the turbo is ok
k

pk4rney

it seems fine what can i check to make sure. the car doesnt smoke thou turbo doesnt make any funny noises. i got told having a bunged up cat can cause this aswell. maybe im just used to faster models. the only thing is i dont get any boost 1 or second realy but it does boost a bit in other gears the only way i can expaine it is its like a weak diesel turbo

pk4rney

has anyone else got some advice

Peanuts

I thought that standard uk cars limited the boost in the low gears, to say something like 0.5bar.
This is why dawes devices or similar give the impression that they give a huge power rise becasue the remove this limiter.

could be tosh though, often is

pk4rney

what should i do then

AshMurc

is the boost control pipework ok? is the restricor pill present? How Subaru's Factory Boost Control System Works v1[1] 01 - Fullscreen

pk4rney

as far as i know everything is ok. im not 100% thou, i know the ecu was reset. all i can say is ut feels like a weak turbo diesel espacialy in low gears. i was gonna take it to scoobyclinic to see if they know what it is. maybe its restricted like the other poster says

AshMurc

my wrx wagon was boosting at just under half a bar due to dodgy vacume hoses and no restrictor pill-- still pulled pretty strong in low gears...

pk4rney

i got told that if you reset the ecu that the car will run low boost until it learns again so it can achieve its highest boost is this true and is the uk impreza boost limited cause it felt like it had some boost in higher gears if so where can i get this changed so i can achieve normal boost or can i take the cat off cause i got told the cat can get bunged and by taking it off you get more bhp but the car can run lean

Peanuts

post #7 tells you how to overcome it.
Removing cats does release power, but its no way near as much as urban legend would have you believe, what it does though is give the potential for more power when you go further with your tuning.
I had a uk99 up to 270bhp with a dawes, green panel filter, sti5 tmic (which I now think was crap as the uk one) and a decat turbo back exhaust.
No remap, but I had a lambdalink to check that it wasnt running lean.

mike799

as already been said,i would double check all pipework on turbo & boost solinoid for splits

pk4rney

im gonna take her out and put some shell v power in her today cause got told off of a few reliable people that this could work. althou maybe its just me because i let my friend have a go with me in the passenger and it felt preety quick. the exact issue is this, the boost doesnt feel strong enough and it cuts about 5000 revs is this the way it should be as i said before im used to my mates wrx. im gonna check for any leaks see if that helps also is knocklink sensor a good idea, what else can i install to make me feel more settled that she aint gonna blow up i dont rag her at all i put the foot down once a day and always let her warm up and cool down.

joz8968

Do the above advise first - check all of the boost control vacuum hoses for splits, perishing, etc. Also check for the restrictor pill in the boost solenoid's bottom hose - see here for its location...

Boost Solenoid Plumbing

If everything seems fine, then it could be because the last batch of fuel was bad... I'd get the current owner to first run the existing fuel down to near empty (or syphon most of it out), then drive to an Esso or Shell petrol station that's notoriously BUSY (i.e. has a lot of daily throughput) and fill up with a decent fuel like Esso 97 or Shell V-Power. Disconnect the battery for about an hour - this will reset the IAM memory of the ECU - and then take the car on a blast for about 20mins...This should optimise the IAM feature of the ECU for the new fuel in the tank i.e. give as much ignition advance as possible (hopefully anywhere between IAM 8 and IAM 16), just before whatever knock threshold the ECU detects.

So, assuming there's nothing wrong with the boost control system, sensors, turbo, engine, etc., you're now starting from the best possible 'clean slate'.

Then ask him for you to drive it again and see how it feels...

TonyBurns

The 99/00 uk cars have a built in emissions thing in 2nd gear where as if you leave it in second for too long then boot it, it cuts the boost back.

Tony

pk4rney

as suspected i took it to the garage put some shell v power in it didnt reset cause got told off of someone that the ecu will learn itself. the car does seem to pull a bit better still stops at 5 thou i take it its because of how much boost its running. also meant to ask where do i get dawes device from do they work what do they do and do they do damage to the engine. p.s how do i know if my maf failes or starts to fail cause ive heard some horror stories bout them what can i do to make sure everything is in order. thanks

tjmatt

Have you checked that the check engine light bulb hasn't been removed to cover up any faults with engine sensors? The light should come on with ignition and go out once the engine is started. I get about 0.7 bar in 1st and 2nd, dropped to 0.6 at high revs, but about 0.8 in 3rd and above. If there is an sensor/engine fault boost is limited to the 0.5 bar setting of the actuator.