i have an impreza turbo 2000 uk and i noticed a few days ago when i accelerate just as the boost is about to start and during the beggining of the boost the engine stutters it didnt do it before what could be causing this? it has a 2.5" cat back system a sus induction kit an sti v5/6 topmount intercooler and a manual boost controller. also i recently put it in for the mot and it passed but i turned the boost down for a week for the emissions and also instead of the tesco 99 i normally use ive been using bp 97 for a few weeks and since these 2 things i got the engine stutter...

 

Might be sparks, had the same issue, it was due to my missus driving it about and not boosting it. So changed them, job done.

Also you could fill up with 99 a few more times, maybe even reset ECU once filled with 99.

 

personally i would NEVER use 97 ron in a scoob. vpower or tesco 99 they are only the same price as diesel now. try switching back to 99 see if that helps at all?

 

Had the same on my MY05 STI. Thought it was the boost solenoid but took it to garage and said MAF sensor faulty. Replaced it with a new one yesterday, now sorted, it seems

 

i normally always run it on 99 and will make sure i stick to it, i replaced the plugs, ht leads, oil filter, oil, fuel filter and new induction filter when i bought the car and ive done less than 5000 miles since also i have maf cleaner which you spray onto the hair thin sensor wire inside, i reset the ecu yesterday but will do it again when i top up with 99 and see if it works was also guna try redex in with the fuel to clean off any carbon build up. it seems strange it started happening when i messed around with the boost and changed to a less ron fuel, could it be anything else or just (plugs, maf or fuel filter)?

 

i have just had to replace maf and idle control valve but i could really tell tho was almost un driveable so think u would deffo know if major part like that

 

Induction kits are known to knacker maf's on classics, especially later cars

 

yes thats right the normal paper induction kits like K&N that use oiled paper knacker the MAF because particles of the oil get drawn into the MAF onto the sonsor wire but thats why i bought a sus stainless steel blitz induction kit there is no oil plus also i bought MAF cleaner spray and used that. there could still be a chance its the MAF but i havent got the engine fault code on the dash showing that at the moment im not showing any fault codes, but it still stutters, i put redex in last night and tesco 99 and will keep putting the good stuff in then reset the ecu again...

 

i did have a stutter problem about a year ago and it turned out to be one of the HT leads was split so replaced with new cheap set, so wouldnt of thought if could be that again as theyre new unless its because theyre cheap and poor quality i also replaced the plugs with NKG laser platinums so theyre good quality and only done about 5,000 miles since putting them in so cant be the plugs... but now it does feel like it did before...

 

hmm maybe leads again then if cheap 1s the may not be up to the job. i had a similar issue in a 200bhp punto i used to have because notmal leads just wouldnt hack it? it is a thought

Also i knew that the maf would go its the kind of luck i have lol but in fairness i had planned for it but thought i would get more than about 20 miles lol. Seems sweet as a nut again now tho so BIG SMILES!!!!

 

yeah think ill check the ht leads when its dark with engine running to see if i can see any sparks if not ill have to try and inspect the plugs but i should of got better leads to start with those were only £30 off ebay last year. i also phoned up my local subaru dealer to ask about a diagnostic they charge £40+vat so about £48 to check it but im guna try ht leads and plugs and keep on with the 99 ron fuel and do an ecu reset and if its still like it ill have to take it for a diagnostic i think ill also check the engine fault codes aswell.

 

i took mine to baz at redbitz in cannock and he sorted it cheap and quick dude? dunno how far herts is but maybe worth a call to pick his brain?

 

maf wont always bring up a code,it could be failing in the working paramaters if that makes sense,so wont flash up a code!
i had a hesitation on mine,checked plugs etc,swaped my maf with a mates and was the same! cleaned the boost solonoid out with carb cleaner and that sorted the prob!!

 

what was your hesitation like? mine stutters and jumps once the revs hit 2000 rpm to 3000 rpm as the boost is building up and turbo kicks in then once its past the stutter it boosts how it should. how do you clean the boost solenoid? is it the block attached to the drivers side shock with boost pipes going to it...?

 

My 00MY Classic did this when run on cr*p fuel. If you're running BP this may be the cause.
Try going back to what you used before prior to swapping parts.

 

it wasnt a violent hesitation but enough to know something was up! i have had it before when a maf went but that was a more violent hesitation!
as said by other people though stick some decent fuel in it and see what happens,you dont want to be replacing parts you dont have to!

 

yeah i put crap bp fuel in it for a few weeks as wasnt close to a tesco or shell, i wish i hadnt but been putting tesco 99 back in it now for a few days, think ill have to give it a few weeks give the ecu a chance to get used to it and then ill do a reset. i checked the ht leads in the dark with engine tunning spray a little water to see for sparks but nothing so not the leads. think i might do the maf cleaner again tomorrow to.

 

it is possible that when i messed around with the manual boost controller for the mot that after i turned it up too much and damaged the boost control solenoid by over boosting or can it handle the boost ok, its not re-mapped standard ecu & td04 turbo.

 

Did you fix this goucon? I have the same problem on my 2004 wr1

 

hello mate its goujon lol... well i had this problem for a good few weeks it even resulted in me not being able to drive the car it got so bad so i had to call a mobile diagnostic guy to come and check it out. he checked fuel pressure and did a fault code check and diagnostic check and he said it was showing as lambda sensor and maf as the problem so 1st i replaced the lambda sensor with a genuine subaru part which was about £140 then that had no effect so got a 2nd hand maf from ebay as a new one from subaru is over £300 and that fixed the problem but i was getting a very violent hesitation and loss of power through the rev range it was undrivable really, touch wood its been fine ever since...

 

Had exact same problem
O2 sensor was the fault. Just unplug it and go for a drive, if the hesitation has gone, you know the sensors faulty.
I replaced it with a £20 bosch lambda sensor from ebay.

MAF usually causes a bad idle, and very poor running on boost.
Poor fuel will cause the car to run badly right through the rev range.
O2 sensor causes poor running pre boost