Why is my impreza juddering?

[bromlio]

After going at high speed then driving at the correct speed limit, why is my impreza juddering? Seems to do it when I hit 70 - 80mph?

Sounds like it is being kicked in the nuts? lol

What could be the cause? Thanks in advance.

bromlio

[thinfourth2]

Your wheels are no longer round

[300bhp/ton]

bromlio said:

After going at high speed then driving at the correct speed limit, why is my impreza juddering? Seems to do it when I hit 70 - 80mph?

Sounds like it is being kicked in the nuts? lol

What could be the cause? Thanks in advance.

bromlio

As doogz said, more info needed really.

Is it a juddering from the wheels/through the steering which could indicate unbalanced wheel, sticky brake calliper or worn bush.

Or is it engine related, which would suggest fuel or electrical issues.

Or indeed even drivetrain juddering such as clutch, driveshaft.

[PHmember]

Is it the awsssoome zorst?

[bromlio]

300bhp/ton said:

bromlio said:

After going at high speed then driving at the correct speed limit, why is my impreza juddering? Seems to do it when I hit 70 - 80mph?

Sounds like it is being kicked in the nuts? lol

What could be the cause? Thanks in advance.

bromlio

As doogz said, more info needed really.

Is it a juddering from the wheels/through the steering which could indicate unbalanced wheel, sticky brake calliper or worn bush.

Or is it engine related, which would suggest fuel or electrical issues.

Or indeed even drivetrain juddering such as clutch, driveshaft.

Hi,

It's from the engine. The best way to describe it is like a cough, when it judders it loses speed.

Not sure the best way to describe the problem, I'm using premium fuel (from Esso) if that helps.

Cheers,

bromlio

[ShadownINja]

So, to clarify, you're going around Silverstone, hit about 100 then decelerate to 70 and you experience the sensation but driving at say 40-50 then accelerating to 70-80 is fine? I would guess some kind of fuelling issue - check the ECU (get someone with a clue to connect it to a laptop). Also worthwhile checking/cleaning the MAF sensor.

[HellDiver]

Probably a piston has melted. It is a Scoob, isn't it?

[bromlio]

ShadownINja said:

So, to clarify, you're going around Silverstone, hit about 100 then decelerate to 70 and you experience the sensation but driving at say 40-50 then accelerating to 70-80 is fine? I would guess some kind of fuelling issue - check the ECU (get someone with a clue to connect it to a laptop). Also worthwhile checking/cleaning the MAF sensor.

Pretty much spot on what I am experiencing!

I think it would be worthwhile doing those check you suggested. Thanks

[bromlio]

HellDiver said:

Probably a piston has melted. It is a Scoob, isn't it?

Yeah it's a Scooby

[bromlio]

doogz said:

Do you have a boost gauge on the dash anywhere?

Is it behaving as it normally does, or is it fluctuating and not holding constant pressure?

Helldiver, come back when you have a clue.

Hi I have got a boost gauge, I will need to take note of what you have said and check it out when I drive it next.

[300bhp/ton]

Also I might be fooling myself, but in my experience fuel related misfires and electrical ones sometimes feel different.

Electrical misfires are very violent, while a fuel related one has a soft of softer edge to the misfire.

[ShadownINja]

bromlio said:

doogz said:

Do you have a boost gauge on the dash anywhere?

Is it behaving as it normally does, or is it fluctuating and not holding constant pressure?

Helldiver, come back when you have a clue.

Hi I have got a boost gauge, I will need to take note of what you have said and check it out when I drive it next.

You haven't already thought to look at it? Why do you have it? For show??

[bromlio]

ShadownINja said:

bromlio said:

doogz said:

Do you have a boost gauge on the dash anywhere?

Is it behaving as it normally does, or is it fluctuating and not holding constant pressure?

Helldiver, come back when you have a clue.

Hi I have got a boost gauge, I will need to take note of what you have said and check it out when I drive it next.

You haven't already thought to look at it? Why do you have it? For show??

It's all very new to me. This is my first high perfomance sports car which I purchased last week, it's a big step up from a 1.2 ibiza i used to have lol, so I'm just learning. Any tips and advice would be handy that's why I came on here.

Cheers

[Carfiend]

Are you getting popping from the exhaust?

I would check if it is one of these before looking at more expensive issues:

• Overfueling (have you modified it?)
• Dodgy coilpacks (where the heat of running at higher speeds opens a break)
• Non coilpack misfire (could be due to spark plugs runnig outside of rated heat range )

[bromlio]

Carfiend said:

Are you getting popping from the exhaust?

I would check if it is one of these before looking at more expensive issues:

• Overfueling (have you modified it?)
• Dodgy coilpacks (where the heat of running at higher speeds opens a break)
• Non coilpack misfire (could be due to spark plugs runnig outside of rated heat range )

It does tend to pop every now or then from the exhaust. The modifications I am aware of it that it does have rediculous exahust on it, and the Cat convertor has been taken off.

Cheers

[ShadownINja]

bromlio said:

It's all very new to me. This is my first high perfomance sports car which I purchased last week, it's a big step up from a 1.2 ibiza i used to have lol, so I'm just learning. Any tips and advice would be handy that's why I came on here.

Cheers

Ah! Typically, the boost needle should rise to max boost that has been set and slowly taper off through each gear. I wouldn't use it as a precise measure of the boost pressure unless you have an expensive gauge; instead use it to monitor anomalies eg if the boost drops while accelating in-gear, rises then pauses before rising or it rises to a lower level than it used to (obviously, it's too late to compare then and now as you're experiencing a problem).

Edit: I would post a relevant youtube video but every fkwit who has posted a video of their boost gauge shows no more interest in the gauge than the start up flashing sequence... which probably sums up the reason most peoples got it installed. They could have saved £200 by just sticking a mini Christmas tree to the dashboard.

Edited by ShadownINja on Tuesday 11th January 15:28

[anonymous-user]

What year scoob is it?

The classic Impreza's ??-01 I think, the MAF sensors were a bit fragile I believe

[Carfiend]

bromlio said:

It does tend to pop every now or then from the exhaust. The modifications I am aware of it that it does have rediculous exahust on it, and the Cat convertor has been taken off.

Cheers

Not knowing Subarus as well as my Skyline I would say that it is picking up the extra air flow due to the bigger exhaust and decat and pumping in more fuel.

This happens to mine on cold days after a bit of a thrash as it needs a remap. So this might be normal considering the modifications and temps in the last few weeks.

[bromlio]

anonymous said:

[redacted]

It's 2000 STI

[Richieboy3008]

bromlio said:

Carfiend said:

Are you getting popping from the exhaust?

I would check if it is one of these before looking at more expensive issues:

• Overfueling (have you modified it?)
• Dodgy coilpacks (where the heat of running at higher speeds opens a break)
• Non coilpack misfire (could be due to spark plugs runnig outside of rated heat range )

It does tend to pop every now or then from the exhaust. The modifications I am aware of it that it does have rediculous exahust on it, and the Cat convertor has been taken off.

Cheers

And the BOOOOOOSt has been increased.

You were getting very loud back fires when you accelerated away. I think it's a fueling issue, but I'm no expert