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EJ257 Hesitation Coming Into Boost

Old 14 March 2017, 07:19 PM
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KeirGers
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Default EJ257 Hesitation Coming Into Boost

Hello everybody,
First of all, this is my first Impreza so bear with me. It's a 2005 55 Hawkeye WRX STi. I thought I got a bit of a bargain, but it's turning out that it may not of been.
so my symptoms are:

hesitation/stutter usually between 2-3k rpm

very occasional see a stutter higher up, around 5k

Worse when cold, first start up in the morning, whilst accelerating up to 30mpg through the gears the car has a noticeable jerky stutter.

Usually, in 6th gear at 60mph it's as if your waiting on the power kicking in, like breaking through a hesitation barrier

If driving the car very very hard, first gear out of a junction, WOT, around 50% of the time, get a complete power loss mid rev range and then it comes back in. Nearly sending you through the windscreen!

So, it's been doing this ever since I got the car and I just presumed it'd be something minor.
The engine management light is on, but due to secondary air injection pump. I fitted blanking plates on the block the other day, and it's had zero relevance to my issue.
Plan was to get the car mapped by Andy Forrest when I'd done basic mods however, I don't want to book it in really until I have fixed this.

Parts I have so far replaced:
MAF Sensor
Walbro Fuel Pump
Perrin Intake
Replaced Spark Plugs with colder rated
Coilpacks from a 40k car
Fuel Filter
Camshaft Sensor

Unplugged the boost solenoid & its working

I also temporarily wired in a cheap eBay boost gauge, its holding a solid 1.3 bar of boost. As far as I was aware, the stock boost is 1 bar? Surely meaning the car had been mapped before?

so, where I'm at now, is I need to check the compression, or would a bad map possibly cause these issues?

The thing that confuses me, is no EML codes, pulls brilliantly once you get it into Boost most times & no smoke, or tell tale signs of anything.

Any advice is is much appreciated!
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Old 14 March 2017, 10:34 PM
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Get it on a dyno and find out, could well be a mapping issue so you could have wasted all your money. could it have been mapped then de-tuned? What fuel you running it on?

Sounds like you need to get it to a specialist to see where you are before tryign to do anything else
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Old 14 March 2017, 11:03 PM
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That'd be the ideal, but a dunno isn't easily accessed in my area.
Im pretty confident all a dyno would tell me is that the car has been mapped anyway.
Worst case scenario, it needs an engine, could do with a clutch anyway so it'd kill 2 birds with one stone.

Ran on 99 octane.

The more I look into ringland failure, the more I look into forged engines.
Seems a common issue, and mine certainly seems to tick a few boxs.
Ill check the compression tomorrow.
Surely it wouldn't pull as well with ringland failure though, holds 1.3 bar happily to redline.
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Old 14 March 2017, 11:13 PM
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Compression test and see where you go from there
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Old 14 March 2017, 11:15 PM
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I'll update on here tomorrow what the results were man.
Have seen a nice forged 2.5 in the 'parts for sale' though, sort of hoping for low compression!
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Old 15 March 2017, 02:45 PM
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I had a similar issue, but not as frequent. It turned out to be the neutral position switch on the gearbox. took it out, it had worn down to nothing. Swapped with a new one - all good!
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Old 15 March 2017, 10:08 PM
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I'll have to take a look at that tomorrow buddy, thanks!

Well, compression test is done. 110psi across the board, give or take an absolute max of 2 or 3 psi either side.
Obviously 110 is low, but it was done with the engine warm, and with a cheap tester so I doubt 110 is accurate.
Was more looking for a substantial drop from one of the cylinders.
So it appears my engine is healthy!

Started taking the air inlet pipe off going to the turbo, to realise the only way to remove it without smashing it is to take the inlet off. And wasn't sure if the inlet gaskets need replaced on these whenever the inlet is removed (?) so didn't fancy de-immobilising the car.
Did notice that the stock inlet pipe, where the jubilee clip actually holds it to the turbo housing, wasn't tight. When I went to tighten it up, it seemed a bit tricky to get on to the housing.
I had to nip out at that point so the cars still in the garage.

Going to order a inlet pipe though, obviously in theory, the car taking in too much air which hasn't passed through the MAF could cause my issues.
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Old 23 March 2017, 02:32 PM
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scout1982
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Originally Posted by KeirGers View Post
I'll have to take a look at that tomorrow buddy, thanks!

Well, compression test is done. 110psi across the board, give or take an absolute max of 2 or 3 psi either side.
Obviously 110 is low, but it was done with the engine warm, and with a cheap tester so I doubt 110 is accurate.
Was more looking for a substantial drop from one of the cylinders.
So it appears my engine is healthy!

Started taking the air inlet pipe off going to the turbo, to realise the only way to remove it without smashing it is to take the inlet off. And wasn't sure if the inlet gaskets need replaced on these whenever the inlet is removed (?) so didn't fancy de-immobilising the car.
Did notice that the stock inlet pipe, where the jubilee clip actually holds it to the turbo housing, wasn't tight. When I went to tighten it up, it seemed a bit tricky to get on to the housing.
I had to nip out at that point so the cars still in the garage.

Going to order a inlet pipe though, obviously in theory, the car taking in too much air which hasn't passed through the MAF could cause my issues.

did youget it sorted mate? If so, what was it in the end?
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Old 23 March 2017, 09:03 PM
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Originally Posted by scout1982 View Post
did youget it sorted mate? If so, what was it in the end?
Ive not gotten any further forward with it bud. The cars still doing it. Gradually getting worse. Almost every time in 1 and second gear at WOT, it now has some sort of fuel cut and tries to put you through the windscreen.
Not really had time to look at it to be fair. Just begging that I eventually get an EML!
Thinking along the lines of camshaft sensor though.
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Old 03 April 2017, 07:48 AM
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Janine Dawn
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Default Mine had this problem 1996 wrx

This worked a treat.runs like a dream! Also squirt egr injector cleaner in pipe at 2.5 revs.
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Old 03 April 2017, 09:40 PM
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Sounds like possibly AFR related , ov course a mapping session would be needed to make sure your trims are spot on / if it's been mapped before with diff supporting mods to what your running now that's your daddy ..
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Old 05 April 2017, 05:08 PM
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Default FuEl problem

Just got back from garage. They said it was a fault with the injector and a dead spark plug. All good now
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Old 10 April 2019, 08:01 PM
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Default Scout 1982

So did you plugs and injector really cure it,please give us an update.intreseted to know as I have similiar

Last edited by stevie turbo; 12 April 2019 at 05:40 PM.
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Old 10 April 2019, 11:16 PM
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Don Clark
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Originally Posted by stevie turbo View Post
So did you plugs and injector really cure it,please give us an update.intreseted to know as I have similiar
Stevie, you are asking about Janines problems with her 96 wrx rather than the op's EJ257 problems
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