UHF

I have this exact same thing, have MY99 Turbo, just had 45k service a few months ago despite being on 27k on the clock, just recently it started to hesitate on light acceleration, kinda holding you foot lightly and it fluctuates rather than driving smooth up through the revs.

I just bought it a month ago, is this my dealers problem?

SCOSaltire

seems it affects alot of my99 and my00 cars.. enough for subaru to bring out some info about the cause of the problem - AFAIK they have put it down to turbulance in the manifold when the turbo is not fully up to speed.

this might be the case - but i am gonna try a few things first...

UHF

Well i'll go back to the dealer and moan, if everyone else does that we can get something done, perhaps its worth starting a new forum area for this so we can get subaru to do something about it!

STi wanna Subaru

iTrader: (1)

SCOSaltire,

Hope the new MAF sorts it mate, I look forward to hearing how it goes.

Guy

Moles Dad

M A F....Major Anxiety Forum!

jonny gav

iTrader: (1)

try and disconect the white wire from the lambda sensor(signal)if the problem disappears its a lambda fault

got the same fault today fitting a new universal lambda sensor

UHF

whats this sensor i've heard so much about, will it damage the car driving it to test it without it connected? where is it btw?

jonny gav

iTrader: (1)

not if you just take it up the road for a test but leave it off and it will damage the cats(with fuel).

i have full de-cat so it won't harm mine

HELLOM8

This thread has info on checking the coil packs.
http://www.scoobynet.co.uk/bbs/thread.asp?ThreadID=74077&Page=1
Cheers.
Ian.

Midget

The problem with the maF sensor is that the element becomes
tarnished and reads incorrectly thus telling the Ecm an incorrect
mass air figure this is not recognised as a fault by the ECM
due to the fact that the mass of air constantly changes with temp,
height air filter etc .It can however be detected with the select monitor if looked at in detail .

SCOSaltire

i changed the MAF last night and did an ecu reset.

Only driven 20 miles.... so this is just first impressions:

Car idles higher... just over the 800 rpm marker... whereas before it was just under.

Car sound different above 5k revs... seems to have more poke.

there is still a bit of hunting at idle when warm.
the car still hesitates a bit when warm.

the next couple of days should allow me to find out exactly how its changed... does seem to be an improvement tho.

the old maf sensor looked bad...
what was clean metal on the new one was clouded and had tinges of yellow on it.
it was oily... i could draw finger prints on the plastic.

ozzy

Phil,

Did you manage to but just the sensor? or did you have to shell out £300 for the unnecessary pipework too?

Stefan

SCOSaltire

just got the sensor...
72 quid



only 2 areas left to look at ... if this not solved it...
coil packs
and
lambda (o2) sensor...

ozzy

I original noticed the same hesitation when I ran my car for a few weeks on NUL. Once I switched to SUL, the hesitation cleared.

The car was fine since, even months after the 30K service. 3 weeks ago, I got the Dealer to fit a de-cat DP/centre and replace the fault O2 sensor.

Ever since I've had the car back, I've noticed the hestitation again. It's just like you describe 2000-3000rpm, light throttle. I notice it when gently accelerating, the car kind of pulses.

I mentioned this yesterday to John Banks when we tested a Tek2.5 in my car. He datalogged my car, but don't know if he logged all the analogue/digital outputs so it might not show.

Interestingly the change in ECU hasn't cured it.

Stefan

Hong Kong Phooey

I get this as well - 2800-3000rpm medium/full throttle
MY99, 52000 miles. Due in for interval service, so I'll see what the dealer says.

ozzy

They'll probably say "they all do that sir"

Stefan

ozzy

They'll probably say "they all do that sir"

Stefan

nom

My take on all this...
2000-3000rpm is where the turbo spools up. It's the point where it starts 'sucking' through the inlet & Subaru seems to have set the standard map to run very lean here (why EcuTek can get such good spool-up results through fixing this). So it's a very touchy area, fuel-wise.
Bad fuel will lead to retard at this point as it's too lean in the first place - produces hesitation.
Good fuel but with a misreading MAF (either faulty or filthy - or an induction kit which changes the air-flow characteristics) the MAF will basically always under-read, meaning that the ecu thinks less air is coming through than actually is, so will feed even less fuel. So the mixture is too lean again.
So... check AFR & knock if possible for confirmation; if not, replace the MAF as a precuation (new ones are much sturdier anyway so should be less to worry about ) and run on a 97RON (not Optimax as if you get a bad batch then it can be misleading). If still there, I don't know what to do
Well, that's how I'd approach it anyway

Jolly Green Monster 2

So should we be all cleaning our sensors?

I get hesitation in second gear if I slow to about 1500rpm and then accelerate again.. usually in a carpark.. I could and try to select first and then all okay.

Where will I find the MAF and Lamrda sensors on a MY96.. ?

Cheers

JGM

nom

MAFs on pre-MY99s is a sturdier type... should be OK.
I think there's always some 'hesitation' because of the standard mapping - it's just if it gets worse (and idling is bad) then it's a MAF problem.
Maybe the pre-MY99s need cleaning too have no idea not very helpful there, I'm afraid...

jonny gav

iTrader: (1)

oops!

[Edited by jonny gav - 7/11/2002 9:32:34 PM]