Pulsing acceleration on light throttle...
 

Hi All,

Recently i've noticed that my MY98 UK turbo has a slight pulsing hesitation when on light throttle. Its more noticable when the cars cold, but it never quite disappears when its hot. The hesitation is only very slight but annoying. If I gently accelerate you can feel the car pulse very slight at about 1 second intervals which also seem to match the AFR meter pulse off the Lambda. If you floor it, it all goes away and the car flies. It only happens on vey light throttle (crusing in traffic etc).

I thought it could be the Lambda, so I've changed that without any success. I've not had any faults logged in the CEL and it idles fines, so I wouldn't this it could be the MAF. I'm also currently running a dawes device boost controller so it can't be oil getting into the boost solenoid.

Any thoughts?

Cheers,

Wayne.

Its completely normal ive had 2 imprezas and both did it only when cold though. Dont worry about it

Same, 98 UK wagon. Exactly the same, just live with it mate, nothing wrong.

Me too I have same with a 98 UK Saloon - simple answer - "just floor it"

Cheers guys for the replies. Well least I know I'm not alone!

Wonder if this problem has been around since they left the showroom? If so, its quite a design fault.

Wayne

I've been wondering wether to ask this question for about 2 years !!!

I've got a MY02 bugeye with quite a few mods but I drive it to work every day including a gentle drive down a few inclines at about 30 MPH (the limit) with the throttle sort of "feathering" and I get the same thing ............... :(

It's had lots done but the 1 second pulse you describe is still there !!

Maybe one of the ECU mappers can shed some light :D

Shaun

I am getting exactly the same thing...

MY00 classic turbo.

I had a TEK3 remap about 9 months ago and it was fine until about 1 month ago.

A definite mis-fire (pulse) at about 1 sec intervals.. happens when cold and hot on lightish throttle.

I have changed lambda sensor, MAF sensor, plugs (originals were PFR6B's and I 've swapped to 7B's. No difference at all.

I did notice though that the plug leads all looked a bit suspect so I'm about to change them...

I'll keep you posted.

PS... This isn't a problem only associated with remapped ecus is it ?

FC

Yep, please keep me posted with anything you find.

I'm running a standard ECU, so if definately not down to a re-map...

Cheers,

Wayne.

Exactly the same thing with my standard MY00 GT. Only when cold, under light throttle and before turbo spools up. I mentioned it at Subaru dealer, they didn't confirm it's normal, but listening to all guys here one would think it is.

Update..

changed my plug leads.... Still have slight misfire /hesitation ..

running out of things to check /swap next...

FC

Just bought my first Turbo (had the sport before)

I have EXACTLY the same problem, cold it feels almost like running on 3 cylinders until it warms up,then it's fine.

Must be normal then:Suspiciou

if its any help, i have a my00 ppp.
mine does the same in the morn when cold,
had a few cars that do this, i assumed it was just cos the engine is cold? and that everything is normal?

feels like a caravan or trailer is on the back of ya car and pulling ya car back a little......

Mine too
 

97 UK Turbo, new plugs, leads, air filter, boost sensing hose, cleaned the boost restrictor, decat downpipe, full decat system.......................................Yep, still does it.
Floor it and it goes away! :nono:

I've had this on both scoobies. The current one has definately got worse in the last 12 months and I do not believe it is something i just have to live with. Within the last 14-16 months my MAF and boost solenoid have been changed. Within the last 3 months I have had new plugs and leads. I was going to change my lambda sensor although i'm wondering whether to bother now. It seems better after an ECU reset but never properly goes away. I've had mine at the dealers and there was no error codes on the ECU. They recon I was just feeling the turbo wastegate open/close as I am running a de-cat. But I've been running the de-cat for 18 months now and it has definately got worse. any other ideas?

I've got an MY99 UK Turbo and it does it.

What you can feel (and see if you've got an AFR gauge) is the ECU changing the mixture looking for the best setting and teaching itself.

I was VERY worried when I first bought the car then fitted the AFR gauge and when I saw that I knew what it was.
Can be a bit annoying ut thats what a scooby does!

"I've got an MY99 UK Turbo and it does it.

What you can feel (and see if you've got an AFR gauge) is the ECU changing the mixture looking for the best setting and teaching itself.

I was VERY worried when I first bought the car then fitted the AFR gauge and when I saw that I knew what it was.
Can be a bit annoying ut thats what a scooby does!"

I wish it would hurry up and teach itself the correct setting.
Anyway, I just fitted a new lambda and did an ECU reset at the same time and it has gone (for now). I will see if it comes back.

Has it come back?

Just interested, cos mine does it and it's a bit annoying

I don't understand why there are so many people with this apparent problem, just imagine that it's an older car, with a manual choke, then remember (if you're old enough) how they drive when on choke, the fact that impreza's seem to do this when cold is just the same...... after-all, most people say it stops when the cars warm....

Mine isn't as bad when it's warm, but it still does it

Mine does it as well only when cold and under light throttle, seems to start as the boost pressure starts to increase, My thoughts was that the wastegate actuator could be slightly opening and closing but I don't have a boost guage to confirm this.

Do any of you guys who's car does this have a boost guage, and if so is the boost pressure fluctuating when this happens?

Wow, ive got a MY98 Stb Forester, and it does this also, very glad to finmd some consensus.

my ppp'ed my99 does this had the lambda checked out by len at subaru for you found nothing wrong with it, try using optimax or tesco 99ron and reseting the ecu and keep using either one all the time, this has reduced it on my drastically i have found.

for the record my previous scooby also a my99 but tek3 , didn't do this well i didn't notice lets put it that way

Done 500 miles today after a ECU reset (with the new lambda fitted) and it hasn't done it once.
Subaru checked the ecu for a lambda fault and found nothing, but if you compare the condition of the old one with the new one there is a hugh difference.
Maybe the old lambda hadn't failed enough for the ecu to report it.


Try a ecu rest by itself. If that doesn't work spend £60 and fit a new lambda.
Phil

It's the Lambda sensor getting up to temperature. The ECU gets a little confused until the Lambda is warm.
To prove this drive with the Lambda disconnected and it will be nice and smooth, due to the ECU using the base fuel map rather then using the input from the Lambda to achieve shoich (14.7AFR).

You can drive for quite a while without the CEL coming on. Infact when I disconnected mine it didn't come on at all......

On light throttle (pressure <= to atmospheric), the wastegate will always be shut so it can't be related to the wastegate.

I had this too!

MY99, developed a problem on low revs, lumpy and hard to drive (perfect when driving on).

New sensor fitted a few weeks ago, cured it 90%, but still seemed to "surge" a bit when cold. That definately didn;t used to happen before.

M.

Still puzzled on how to do a ECU reset without pulling off the battery. I've fitted a new Lambda, but not reset the ECU - maybe I should.

If the actuator is broken it could be opening???

Do a search here on scobbynet for instructions how to do a rest.

I've done that before but I always come up with this page:

http://www.saxonfields.freeserve.co....iag%20Page.htm

I get confused at the "Connect Read Memory Connectors & Test Mode Connectors" bit which then links to a picture of the instrument cluster???

Where are the read memory connectors, surely not in the instrument cluster???

plugs under steering column, just stick your head up:
set of black and set of green.
http://www.saxonfields.freeserve.co....connectors.jpg