Hi chaps back again with another problem, slowly working through them all!

Cars a 2004 UK STI prodrive performance pack dyno'd at 315bhp.

Ok is it normal for Scoobies to be so laggy? Driving around town normally is a chore as there is little torque or throttle response. When going WOT it takes an age to react and start spooling, when it does it comes on strong though and car has plenty of power.

When slowly accelerating through the gears at low rpm I believe I can hear compressor surge or a similar fluttering noise from the O/S/F ( turbo side ) of the car. Only mod is a Blitz BOV fitted by previous owner.

It may just be the way they are but our Evo picks up instantly and is sharp as a knife on the throttle despite having a much larger turbo and inlet tract, really makes the Scooby feel dull and dead unless your fighting to keep it in the boost thresh hold!

Any advice on where to start looking? Checked all inlet pipes etc for boost leaks. I've heard someone suggest cleaning the Boost solenoid, where is it located and how do you clean it?

Thanks!

 

Would start by putting the original recirculation valve back on.
If the blitz valve is old and leaky I doubt it would help.
25 pounds of breakers on here.

 

Look into getting a Harvey Smith Trick up-pipe, (Now sold by AS Performance), and a map tweak.

Better spool, more low down torque, better throttle response.

I have one on a forged 2.5 with an HS TD0520g, makes 1 bar at 2800 rpm.

 

What's that pipe replace? Looks like a decatted downpipe?

 

It replaces the up pipe from the exhaust headers to the turbo. Have one fitted on mine and ported the headers, the difference is quite surprising

 

I wouldn't be looking at replacing uppipes etc. If it is that laggy chances are it is something failed.

Such as bboost control solenoid etc.

I would look atsimple stuff before big spending, it could be a collapsed cat etc.

What boost do you get when?

 

Evo's are twin scroll aren't they, make a fair difference.

 

I doubt there is anything wrong with it, it's an STI and they just don't pick up well until they get to about 4k rpm.

 

I have a 53 plate sti, mine drives superb. No lag at all. I have just over 300lb torque @ 3500 rpm.

Lower down the rev range I have over 200lb @ 3k rpm.

Who remapped the car ? Any dyno sheets at all ?

I have had a open source remap. Only mods are full 3" cobra turbo back exhaust and panel air filter

 

I'm with J,9 times out of 10 the problem is simple just be systematic and go through all boost supporting parts and you will find the problem.SJ.

 

Already cleaned boost control solenoid and didn't help.





Cast your eyes over those please and see if there's anything out the ordinary.

 

Just so you can compare.

As you can see @ 3500 rpm you have 225 torque i have around 310 huge difference , same in BHP you have around 150 where i have around 190bhp.
Your AFR looks good with no issues tbh.

Your torque is good but tbh its all over the place, its not very stable, drops off quite quickly then picks back up again.

Can i ask who mapped your car ? Did you buy the car with the map all ready in place ?

 

We bought the car already mapped. Do you think this is more an issue with the map than a mechanical component?

 

That is my belief. I think its just the map tbh.

When you purchased the car, did the seller tell you who had mapped the car ??

 

doesnt look laggy according to the graph.

different cars will be different in responce, around town the turbo won't be spooling so will be pretty gutless low down till it comes on.


Best way to test, find a nice long stretch of road, put the car in 4th at around 2500rpm (assuming 6 speed) and floor it, see when you feel the turbo kick in, around 3500-4000rpm is normal

 

AVCS working ok?

 

The clue is in the name: Harvey Smith trick UP-PIPE.

LOL

 

Not really, being new to Subaru's I've never come across the term 'up-pipe' before, only downpipe being the exhaust component immediately after the turbo.

I appologise if my ignorance offends you however I believe it to be a justifiable question for someone who clearly isn't as well informed as you...

Anyway back to the questions from people who are actually being helpful. I've no idea where it was mapped unfortunately. There's no invoice and although I've spoken to DynoTech as their name is on the printout they advised me it's quite common for the dyno to be hired out to other mappers and they certainly don't work on Subaru's themselves.

It may just be the way it is, I understand the principles of a turbocharged engine being low compression and relying on turbos which have a delay before reaching boost threshold etc. however I've had the pleasure of owning a few boosted cars now ( Meg 225, Meg 265, Saph Cossie, Evos ) and none of them have been this lazy or delayed to spool. I was expecting more response from the relatively small turbo and TMIC inlet tract.

 

Sorry to say it but, what you're experiencing is what many of us that have driven both the WRX and the STI realised early on. STI ain't all it's cracked up to be in Newage guise, fine if you like to drive everywhere at 3.5k + rpm and like pressing the clutch a lot, but for us mere mortals that want a car that responds from circa 2krpm and goes to 60/80/100 mph like a scolded cat, as well as having a decent amount of mid range shove available for real world driving situations, without having to be up and down the gear box all the time like a yo yo, then don't buy an STI, and don't get me started on the suspension, or the blue interior, both of which are un-bareable. All IMO of course.

And yes I can afford one.

 

hark at you, bet your pet phrase is 'they dont build em like they used to'

 

try the test i said above and feed back, it sounds like you just need to get used to a more revy engine though

 

Sense of humour bypass alert........did you miss my "LOL"

Oh...and my suggestion of an HS Trick up-pipe...oh...wait.....

 

The car is a PPP so Prodrive mapped it, the boost response is typical of their map, its a one stop map for all the PPP cars and not tailored to an individual car.

It looks a bit high at 1.5 bar so its possible it was mapped since but you will need someone like me to plug in and tell that

The sweet spot of an Sti engine is 3500 to 3700 rpm if you are trying to make it go below those rims especially in higher gears it simply "won"t". So its a matter of driving the car to suit the engines optimum power band. its not a diesel despite having a turbo

It has a VF35 turbo as std and there is certainly no need for different up pipes etc that should spool as well as it can be allowed on the stock headers and up pipe.

So, just be aware of the cars characteristics .. as has been mentioned if you really do want a vehicle that responds like a train from 2000 rpm then you need an Audi :-)

But a custom map done in detail would improve what you have now

cheers

bob

 

There is your answer take a trip to see Bob and get it remapped.Better still contact Bob have a chat and see what he suggests you do to the car before the mapping to improve the result.
Then enjoy the drive home.

 

What's the typical spool time of a decatted vf35 compared to td04 remapped of course.
I've bought a vf35 and wanted it fitted and mapped to a decatted wrx 05?
Cheers 🍻