holding back and jumping on boost...
 

Car just bought yesterday. When i go into boost she starts jumpin slightly and holding back nearly like dirty fuel but its not i don't think. Could it be the fuel im running it on? Put a tenner of 'premium unleaded' in today as i got proper lost in the middle of the sticks in ireland thinking it was similar to bp ultimate but maybe its not as high an octane rating? Also how much you guys pay for a set of pads? Gotta put on a new set 2mara.

Sounds like the problem I've been having for the last few months since I bought my00 Uk turbo. I have changed maf, boost solenoid, plugs, airfilter. It was a combination of my dump valve and the incorrect size restrictor pill in the vacuum hose. Which model u got?

What model, year, spec, mileage? When was it last serviced and by who? Any modifications?

The hesitation/jumping could be a number of things - easy fixes such as dirty/faulty MAF, front O2 sensor, dirty fuel filter or more serious like a cracked ringland.

An easy test to do is a crank test... block off the fuel line and start the engine. Then when it runs out of fuel and cuts out, turn it over again and have a listen... the cylinders should sound the same (e.g. putt - putt - putt - putt - putt - putt... etc) if any are uneven (e.g. putt - putt - puh - putt - putt - putt - puh - putt) then you could be losing compression on one or more cylinders via a cracked ringland or piston ring - in which case, get it checked over by a Subaru specialist. Other indicators of of a cracked ringland are high oil consumption (more than 1 liter per 1000 miles) but it sound like you've not had the car long enough to track the consumption.

Hopefully it's one of the more simple fixes like a dirty MAF though.

i think i get the same problem,bought my car yesterday.I've got a 52 WRX with 55k miles, oil & filter last done in March and before that about 8,000 miles ago where the plugs and filters were changed. The car is completely standard apart from an STI backbox. But the same principal i put my foot down and it seems to hold back as if not enough fuel is getting in then it suddenly catch's up.

Good choice of car (same as my current one!) :biggrin:

The OPs problem sounds like he has hesitation when accelerating - not sure if your description sounds quite the same.

What RPMs are you doing when you put your foot down? You won't get any proper grunt until 3k RPM as the turbo needs to spin up first - took me a while to adjust my driving style to suit when I go my first Scooby - so it could just be turbo lag.

If the lag seems excessive, you may well have the wrong size restrictor pill or your boost control solenoid (BCS) is a bit sticky and not opening exactly as it should (hence struggling to make boost initially, it then opens, bleeds off enough pressure and hits target boost).

In short, you issue could be a number of things but I'd say the first place to look is your boost control pipe work including cleaning the BCS (see scoobypaedia for more info on Subaru boost control).

Have a similar problem on my Spec C, took it to my dealer and its my maf sensor :( of course if you dont take it to a dealer you can spend alot more cash finding out what it is, took them about 2 mins to diagnose the problem with mine.

Tony:)

Have you replaced it yet? If it's the same as a newage WRX, I have a spare, fully tested (by PowerStation) nearly new one (used for about 1000 miles with a paper filter)? PM me if it's of any use.

97 wrx 2l turbo v-limited jap import 58k miles.

It doesn't happen every time just some times, its nothing serious but i know its gonna do my nut in tryin to find out what it is.

Sometimes it holds back at bout 5-6000revs sometimes as sonn as boost kicks in. Sometimes doesn't happen at all.

I first thought dirty fuel but filled up today with bp ultimate and it is a bit better but still there.

Im thinking oxygen sensor or maf sensor.

She seems a tad under powered aswel but not all the time its very hard to explain! Never had this problem wit my glanzas so its new to me...

How much we talkin for a dealer diagnostic?? Im preparing myself...lay it on me lol

Not sure about a main dealer but 2 hours on a dyno at PowerStation to diagnose my cracked ringland was around £300... if you have access to a laptop and an ODB cable (can get them off eBay quite cheap) and a copy off ROMRadier then it would be worth doing some data logging to see what the ECU is doing (eg pulling ignition advance, detecting knock, etc)

I HAVE A UK 2000 THAT IS PULLING BACK AT 4K RPM ANY IDEAS ITS HAD A BRAND NEW MAF SENSOR NEW BOOST REGULATOR ITS DOIN MY HEAD IN

Update..

Ok see if anyone can relate to this, only had the chance to test it today up to my eyes in work...

This is what it feels like to me: I Put foot down in any gear engine seems confused and takes a while to work out correct air fuel mixture resulting in a pause of boost and what seems like an over-delivery of fuel or air (that sort of splutter sound) and then spooling up again once its got its mixtures right, sometimes after this confused stage she boosts and goes 100% sometimes she seems to have agreed on the wrong mixture resulting in lack of power untill i lay off throttle and spool up again. Sometimes she goes 100%.

Does this sound familiar to any of you? It sounds like a 02 sensor to me or some kind of faulty sensor to do with the delivery of fuel and/or air.. Then again i could be waaay off...help? I have a week off next week so gonna dedicate that to fixing the big lady but have limited funds so main dealer is n/a. Gotta get the paws oily..

I know what you mean, mine does what you describe too. Its a MY00 UK Turbo PPP with standard air filter and standard dump valve, i've replaced the MAF which appeared to sort out an off boost problem, but as you describe its an odd feeling. As it comes onto boost its a little hesitant but initially pulls well, if not smooth, but then after a split second appears to hold back and feels down on power, not a lot just a little. I too thought it was fuel but a change and an ECU reset made no difference. Tonight there was a noise of what appeared to be escaping air as it came onto boost but it only did it once so have not been able to replicate it.

Its starting to do my head in too!!

Any advice would be appreciated.

Yes there is a dump valve fitted what could be the issue with this?Iv heard of dump valves giving bother in scoobys what you recommend?

I know how you feel bro its doin my nut in i know its somethin so simple to do with delivery of air/fuel or ignition.

Standard turbo. Does the turbo not need a dump valve of some sort silent or not? Closing up the holes won't allow the air to dump and could damage the blades??

did u find out what was wrong with your car mate mine does the same?gets bit better then run like crap again? cheers rob

Yea mate it was the dump valve it was stickin every so often had to take it off an spray wd40 around the piston an inside it done the job goes 100% now

god knows whats wrong with mine then?i run with out dump valve . i hate my subaru sometimes lol good to here yours ok now mate

Could be a maf sensor best bet is to get er plugged in on diagnostics at a garage mate

i got sim tec so maf less yer i know but i need some1 that has access to sim tec to.