Acceleration Stutter In Classic (solved)

[thegetgo]

Hi everyone

My year 2000 Impreza Turbo has developed a small stutter during hard acceleration.

It happens mid revs -ish. Makes no difference if the engine has been running for a while or just freshly started.

Anyone any ideas what it might be?

I have taken all the cats out and replaced with a sports cat in down pipe, no other engine modifications.

GetGo

Edited August 15, 2009 by thegetgo

[GalaGogsie]

Hi mate

You could try your lambda sensor in the down pipe?

[soundie]

was it remapped after changing exhaust?

[cullenmin]

I had this happen to my old MY00 uk turbo, mid revs accelerating and the car took a stutter.

Turned out that the cambelt tensioner pulley had seized so it was the cambelt that took a stutter. Tensioner and belt replaced then I had no further issues.

Might want to get that checked as it could be awfully expensive if the belt skips a tooth or two.

Rich

[lewisscoob]

Have you done a fault code check? Could be the MAF or the boost solenoid.

Never heard that beofre Rich, you have me worried now cause mine does the same, mine came up with the MAF sensor fault code so presumed it was that... not had it running since I got the maf changed so not sure if thats sorted.

[bobbyc]

Had a similar problem on one of my classics & it was the MAF sensor, they don't seem to like some induction kits & the wire gets choked up, I changed the MAF & went back to a panel filter & never had a problem after that.

[thegetgo]

Thanks for all the replies, Dudes.

Definitely some stuff those that I was hoping wouldn't come up!

Well, I have checked the car and, according to the lack of ECU fault codes, it doesn't think there is anything wrong.

bobbyc: Had a similar problem on one of my classics & it was the MAF sensor, they don't seem to like some induction kits & the wire gets choked up, I changed the MAF & went back to a panel filter & never had a problem after that.

It is still running the original airbox and panel filter (filter is not the original one! It gets changed every service!), due to the problems these can have with induction kits.

I was hoping that this would avoid any MAF issues.

Soundie: was it remapped after changing exhaust?

It wasn't remapped after the exhaust, but I haven't changed anything in over a year and a half. I would have expected a mapping problem to have made itself evident in that time, no?

GalaGogsie: You could try your lambda sensor in the down pipe?

It just passed it's MOT emissions about 2 weeks ago. The stutter was evident before this time.

Does that mean that the lambda is ok?

Cullenmin: Turned out that the cambelt tensioner pulley had seized so it was the cambelt that took a stutter.

I'll get the tensioner and cambelt checked, but I take the thing to Subaru for services and the belt was changed in 2005 (big service).

Could it have seized in that time? It only does normal mileage (less than 10k per year).

Again, Ive never heard of this either (But that doesn't mean much! ).

Does any of this info give you lot any more ideas of what it might be? I might as well sort it all while I'm at it!

GetGo

[dan_jess]

The maf can go without throwing up a code. I just got one this morning from AS Performance, £85 delivered, only ordered at 3 oclock yesterday

[thegetgo]

The maf can go without throwing up a code. I just got one this morning from AS Performance, £85 delivered, only ordered at 3 oclock yesterday

Cheers, good info

Would I be able to tell by looking at the MAF whether it was knackered?

GetGo

[dan_jess]

If you have a multi meter you can test it

[drb5]

Plugs or leads is my thoughts.

[thegetgo]

If you have a multi meter you can test it

I do have a multimeter. I'll give it a go.

Cheers

[thegetgo]

Plugs or leads is my thoughts.

If it's them would it not be in evidence all the time, rather than just at certain revs?

Getgo

[dan_jess]

Taken from the P1 owners forum

"I tend to consider 1.02~1.04v as fine.. anything over I do an ecu reset to see if idle hunts etc etc

the one the other day with 1.32v with engine off.. lol was deffo fooked!

So with engine off & ignition on, check the voltage from your maf sensor

Use a multi-meter, and put the - probe on the Black wire (2nd one across from left to right) and the + probe on the end wire

Just push the probes down into where the wiring goes into the multi-plug

[thegetgo]

Taken from the P1 owners forum

"I tend to consider 1.02~1.04v as fine.. anything over I do an ecu reset to see if idle hunts etc etc

the one the other day with 1.32v with engine off.. lol was deffo fooked!

So with engine off & ignition on, check the voltage from your maf sensor

Use a multi-meter, and put the - probe on the Black wire (2nd one across from left to right) and the + probe on the end wire

Just push the probes down into where the wiring goes into the multi-plug

Cheers for that!

Such detailed info aswell!

I'll see what it throws up.

GetGo

[thegetgo]

Here's where I connected my multimeter (there is no black wire!):

If that's the right connection I've just had a 0.932 V reading.

Is that too far out of the 1.02-1.04V bracket?

GetGo

Edited June 25, 2009 by thegetgo

[cullenmin]

I'll get the tensioner and cambelt checked, but I take the thing to Subaru for services and the belt was changed in 2005 (big service).

Could it have seized in that time?

But did they replace the tensioner pulley too?

Be interested to find out what the cause of this is now since there are many possible causes of this fault your having

Rich

[~ ~ Cal ~~]

I had this on full boost at the top end a while back. New plugs and a small tweak cured it - it was running too rich at the top end but the plugs were not helping

Fickle beasts ain't they !

[thegetgo]

But did they replace the tensioner pulley too?

Be interested to find out what the cause of this is now since there are many possible causes of this fault your having

Rich

Good question.

Don't know.

(Not a great help, I know!)

[thegetgo]

I had this on full boost at the top end a while back. New plugs and a small tweak cured it - it was running too rich at the top end but the plugs were not helping

Fickle beasts ain't they !

To be honest, this is the first problem I've had in about 6/7 years of owning the car.

(If you don't count the crack in the radiator expansion tank. But that happened 6 months ago, so still 6 years of trouble free motoring)

It hasn't been serviced in about 6 months, so it's probably due a set of plugs anyway. I'll definitely do that before thinking about belts and tensioners etc.

GetGo

Edited June 25, 2009 by thegetgo

[thegetgo]

DanTerzo,

Is that the right way of measuring the voltage across the MAF?

Hope I got it right.

GetGo

[phil1967]

DanTerzo,

Is that the right way of measuring the voltage across the MAF?

Hope I got it right.

GetGo

hi mate had similar problems on my old classoc and found it to be my airflow metre it had got clogged up with oil from my after market sponge filter.binned the filter replaced it with the original paper one and replaced the airflow meter and was sorted.hope this helps.goodluck

[dan_jess]

Hi mate, i got that info off the P1 owners forum, it was quoted from Simon (Jollygreenmonster) a well respected mapper and it worked for me, hope you get your problem sorted out

[thegetgo]

Well, I had a service done, oil, filters, plugs and now the problem has disappeared.

Must have been the plugs.

Glad it wasn't the MAF!

Cheers all that helped.

[cullenmin]

Good to hear its sorted