Turbo 2000 Lacking Power/ Holding Back
 

Hi all!

I have a problem with my 99 turbo 2000 that is driving me insane and hope there is someone who can help :( . I will try my best to explain....

the car starts and idles fine... When i start to speed up the car seems to hold back like its spluttering, when i plant my foot it stops but feels about 170bhp. I have checked for boost leaks ( cant find nothing ) car had a new maf ( still nothing ) also a new fuel pump ( still nothing ) new fuel filter ( still nothing ). The car is not giving me CEL so i just am really not sure what it could be. It holds back bad and hope someone can help.
car is standard td04 just has a decat exhaust.

any ideas i would really appreciate

Thanks. :)

Could be the fact you have an unmapped decat.
Did you replace the maf with a oem item?
Did you reset the ecu after fitting?

Ive similar problem been informed its the maf sensor.

Thanks for the replies, it used to run fine with the decat so i no its not a map issue, ive also decated my previous imprezas with no map with no issues, replaced the maf with a oem one and reset ecu. I just cannot figure out what the problem could be. It splutters like a missfire at half load then under full load it pulls normal just alot of power loss.

What petrol are you using?

I only use v power mate

Have you checked plugs,condition&gaps?
Checked HT leads for damage and resistance?

Might be worth swapping the fuel pump if its on the original, gives you chance to check the pump sock/filter is clean, also when was the fuel filter swapped.

If you have a new fuel pump, filter and maf, may be worth checking HT leads, coil pack and spark plugs. May even be fuel injector related.. other than that is the air filter clean? If you check all those things then you've checked the 3 main areas for cause of fault. Ignition, fuel and air.. may be worth trying to get hold of a known working maf as well.. also check the maf wiring
Let us know if you find the problem

Thanks for the replies i really appreciate it. As i said in previous comments fuel pump and filter were changed around 2 weeks ago and plugs around the same time, maf was changed just after with a genuine oem one.
Today i noticed whoever installed the decat downpipe has left the bottom bolt off where the downpipe bolts to the turbo. All 4 other bolts are tight and it dont seem to be blowing from there but could this be the problem? The HT leads seem to be in good shape to what i can see as they are not the ones where the little rubbers on the ends pull off. Thanks

The fact that it misfires/splutters at partial throttle but not at full throttle would rule out ignition components to me, if they were breaking down at partial throttle it would worsen at full load.
I would start with checking the turbo to intercooler hose and intercooler to throttle body hose for splits and secure fitment.
If either of these aren't sealed you would get unmetered air entering the engine while off boost/vacuum = spluttering.
Then while on boost you would have pressurised air being forced to atmosphere instead of entering the engine = power loss
Also worth checking the BOV is operating correctly, it would give similar symptoms if faulty.

Really appreciate all the help guys.
can confirm the BOV is working fine with no issues and all pipes have no splits and are tight and fitted perfect. Car has been pressure tested and smoke tested for leaks and cant find nothing. Its hard to explain the problem as i build revs pulling off at around 2k - 2.5k revs it holds back like a splutter. Soon as i plant my foot it will not splutter but feels very slow. Ive owned scoobys before ( same model ) and they was alot faster ( also standard ).
im loosing faith in it and just cant see the light at the end of the tunnel lol.
any more ideas would be appreciated :)

Do you have a boost gauge fitted? Could rule out a lot of things if you know it's producing correct boost pressure.

Yes i should of said it has a boost gauge, hits 0.9 - 1 bar of boost

In that case I would carry out a compression test to rule out any internal issues.
Was there any coinciding issues before it started happening?

have you checked for codes using the diagnostic connectors under the dash?

One difference of part throttle and full could be closed loop and open loop fuelling. If it sputtering on part throttle and not full it could be an o2 sensor on the blink. Can you get a diagnostic tool on it?
They are only a few quid on eBay and it would tell you if there are past or current fault codes.

i was thinking it might be lambda related..

I checked for codes with the connectors under the dash and it shows no codes. The holding back happens between 2-3k rpm but under boost its dont feel like a subaru at all. Wouldnt suprise me if a corsa overtook me lmao.
do you mean the sensor on the downpipe? As i also said before where the downpipe bolts to the turbo there is a bolt missing would this cause such problem?
really do appreciate all the help

I'd be inclined to buy a cheap Bluetooth obd adaptor. The dash connectors would likely only tell the current live code not anything historic.

As for the missing bolt I doubt it would cause it. You would smell exhaust gas if it was leaking. I had exhaust gas coming in the cabin and the car screaming like a banshee under hard accel when the gasket failed because that same nut had come loose, but otherwise it was running fine. It's pretty difficult to get to, to get any meaningful torque on it. it's worth trying to as the gasket will fail for sure after some time. it should be a 14mm nut and stud and you'll need an extension bar and flexi joint to get at it.

Even if the downpipe was blowing it wouldn't give you the symptoms you describe.
Considering you haven't had the CEL come on there won't be any codes stored apart from if it's had issues previously.
When did the fault first occur, while driving or after being parked up or after changing something etc?

I'm haveing similar issues as you but mine just seems to be playing up idle now.. had to begin with same problem as you no boost bogging down spluttering!! Mine only started doing this after I took all the air filter off to fitva samco hose kit .. I tried a mates maf which done nothing then bought a eBay one which solved the boost issue just ever so slightly hesitation on tick over well that maf lasted 3 days before it kept cutting out.. so bit bullet bought a oem genuine maf all fine now accept still got this annoying hesitation on tick over , I've changed idc valve tps sensor o2 sensor , coolant temp sensor and changed vac lines on boost solenoid .. im still convinced it's the maf sensor but it's brand new from Subaru . I'm getting a boost/smoke test done on Wednesday il let you know how I get on

Nothing was changed it just started happening, i have noticed tge car does idle low around 600rpm. Am i right it thinking it should be around 900rpm?

Yes mine idles around 900 mark

What does this me? It sits at around 600rpm do you think this could be something to do with my problem

Sounds maf related still .. are you sure you used a brand new oem Subaru one and not one of eBay