jim scooby wagon

Hi, I've owned my 99 Impreza Turbo for 3 months now and have been trying to solve the following problem....when accelerating it seems as if the boost is being turned off then on then off so it hesitates slightly before surging off again, it seems to be worse when cold under gentle acceleration? I have changed the spark plugs, fitted a new MAF (no difference) and have a new set of magnecor leads to be fitted at the weekend. I have cleaned the 2 port boost device which is on the suspension strut (name escapes me) Any ideas as its such a fantastic car, just has this slight annoying hesitation. Not sure if this is a fault as well, but when starting from cold it will rev to 2k and then stay at 2k for some time? It has been well looked after and serviced like clockwork. Thanks in advance..jim

Martin 2010

iTrader: (9)

hi mate,

has it got any mods, been mapped at all?

does it seem like its boosting then cutting on and off and juddering, if so does it do more when its hot? if so i had this problem with my uk Turbo, it turned out to be the type of plug i was running was causing it mate not just the age of the plugs. id advised gettin a set of ngk pfr7b for a re mapped car, or a pfr6b for std form car.

jim scooby wagon

Hi,
its completly standard at present, it had the symptoms before I had it serviced and the plugs replaced.(I will check to see what ones were used).
No juddering, it just pauses, accelerates then pauses, but only slightly, most passengers don't even notice it, but petrol heads do?! cheers jim

Martin 2010

iTrader: (9)

yeh if uve done the other jobs ie cleaning boost solinoid, changed maf for a good one. then id defo wip the plugs out and ahve a lok at em, i had problems with the other ones except the ngk pfr7bs n 6's just missing under the load of boost as its just blowing the spark out.

TonyBurns

iTrader: (3)

You wont have any issues with the PFR6B's, you dont need the 7's (these are a colder plug than the 6's) until your above 300bhp, even the PPP'd 2ltr STI's didnt need them, the JDM new age cars come with them standard though.

There are a few issues that can cause your problems, idle control valve, maf sensor, incorrectly gapped plugs etc.
The cold weather may also be an issue, and did this issue start shortly after a service/plug change, being precise may be of benefit for you

Tony

jim scooby wagon

ok will take the plugs out and have a look, however it did have the problem prior to the plugs being changed?
I ran the flash codes which came back with the knock sensor? The garage said not too worry about it?
The cold weather has effected its rather high idle when starting up?

jim scooby wagon

Ive checked the plugs, they are the PFR6Bs and correctly gapped...

Triple filtered

iTrader: (26)

unplug the lambda sensor from the downpipe and take it a run.........see what happens.

jim scooby wagon

Right, might have cracked it now? I have unplugged the Lambda sensor and it ran really well with none of the previous symtoms, it did use 1/4 tank of fuel to travel 25 miles tops !!!(with some quick bits!) until the check engine light came on, so travelled very slowly home. I have plugged it back in and the symptoms are back. So does mean that I need a new lambda sensor?? Thanks Jim

Triple filtered

iTrader: (26)

I'd say so. Universal 3 wire ones on ebay are around 15-20 quid. Better than £80 for a bosch item IMHO but I'm sure someone will be along in a minute saying theyre sh@t and youd be better with the bocsh.

Personally, I think these cars are so cheap now, you're throwing money away putting genuine parts on them.