Good evening! guys and gals.


i have a slight thing with my 160k mile, w reg (MY2000) Turbo 2k.

it has a few mods, prodrive exhaust and centre decat, with a VTA Dump Valve(previous owner installed dont judge me).

the car when accelerating seems to fluctuate in terms of its power delivery, if you could imagine a dyno chart i can only describe it as looking like a wave pattern or to put it another way, its like sloooooooooww motion kangerooing, . any ideas?

Also i was accelerating the other day was on boost in 3rd not gonna lie was going for it. When all of sudden it just lost power completely, all i had to do was dip the clutch then reage and the thing was normal, its never done it before or since and other than above car is fine.

Car is always run on Vpower, and not showing any codes.

Any ideas? or questions i need to ask or answer?

 

Your having boost issues just like me! The sudden loss of power is the fuel cut that is triggered by the ECU in the event of excessive boost pressure.

I'm having the same problem and still haven't really got to the bottom of it. I've made it a lot better though.

First thing to check is the vacuum hoses that leave the compressor housing and go to the actuator and boost solenoid. There's also a tee piece on this pipe. I'd bet there's a leak somewhere on there via a cracked hose.

 

Forgot to mention my car accelerated in the same way yours does, kinda like lifting the throttle and putting it back down every couple of seconds!

 

well its only ever Peaked at 15psi which i work out at 1bar which is normal i think, i figured cracked hose, the car is old, i also figured ****e fuel due to having less than a quarter tank, i never normal let it go this low.

i dont have a boost controller nor would i ever mess with one, i do however have a ECU reader system which monitors many things, Throttle position, Knock change, past and present codes, boost pressure and coolant, ect, also logs the peaks of each of these, and this is how i know its not gone higher than 15psi (1bar)

 

Thats exactly what its like, ironically its worse at low revs on mine, when its on boost it kinda naffs off not entirely but its barely noticable at WOT.

i thought it could be the MAF.

 

The fuel cut is very close to that anyway mate, and your target boost should be about 0.87bar as standard. I think the fuel cut is 1.07bar, I'll have a look at my map to confirm.

Have you got one of those fuel cut defenders fitted? Mine had a Supechips one but it packed in and I was getting fuel cuts all the time. My boost was set at 15psi also. That's before I knew anything about these engines. Since then I've removed the FCD and boost controller and ESL'd my ECU.

 

not sure, its got the prodrive exhaust and spoiler, and i did wonder if it was mapped as its doing brilliant mpg 28-31.

also had the thought it was mapped for a mod thats since been removed.

tbf you could be right, the boost doesnt normally go over 12psi which would put it in that range, i just thought the turbo 2000s worked at 1bar, no i dont think i have one of those, not sure where to look anyway.

 

found this, almost identical to what it did tbh!.

nice to know i have the feature to be honest, i dread to think about what would of happened.

 

Hard to say if its been mapped or not but if it had, the fuel cut limit would have been raised to suit the new boost pressure. I bet you've had a slight "bleed" causing the boost pressure to rise to 15psi and it's just getting a little worse and touching the fuel cut limit. I'll double check the pressure shortly. Gotta run out to the car to grab my laptop!

The T2000's are defo 0.87bar or 12/13psi.

 

that makes sense as ill be honest ive tried to make it hit 15psi to no avail, can only assume ive got some sort of leak, its all samco hoses though so i thought id avoid this, what pipes am i looking at ill be honest im clueless.

 

should point out i only did this twice to see what the actually pressure normally is. and 12/13 is about normal.

 

Do you know if you have a 2 port or 3 port boost solenoid?? Mine is a 2 port, so check this if it applies to you:

If you take the turbo heat shield off you'll see a small vacuum hose coming from the actuator with a tee in the middle and then continues to the turbo compressor housing. Check both of those hoses. Be careful though, there's a tiny restrictor pill inside the one that's on the compressor housing!

Check the actual tee itself for cracks. Then there's the hose that goes from the tee over to the boost solenoid. Check it along its length too.

Generally just check that all the connections are good. I'd put money on it that you'll need to replace them.

 

 

Lines 1, 2 and 3 in that photo.

Only applies to the 2 port system!

 

Whats the Restrictor Pill do.

 

and whats a boost solenoid and whats it in that pic?

 

Ok so the top right side of the photo shows the boost solenoid sitting on a white box with two small hoses connected. It bleeds pressure away from the turbo actuator allowing the boost pressure to rise to a controlled level beyond the level the actuator would normally open at. (7psi).

The restrictor pill prevents any sudden spikes of pressure going along the pipe to the actuator. I imagine this gives a nice smooth delivery of boost. Other than that I don't know! I know it needs to be there though or all sorts of weird things happen. So if you need to replace that section of pipe, take the pill from the old pipe and install it to the new pipe.

 

ah i see, its looks simple enough to look, at 160k miles i bet one or more have perished.

 

For sure! Mine were bad at 101K.

It really is simple once you understand how it works. Yours could be a 3 port solenoid though. It'll be piped up differently but the parts are in the same locations. Again, just check all the hoses to and from the turbo.

 

and replace one at a time so i dont get confused!.

ha ha

you sir are a legend.

 

That's the idea! Take your time and all will be well

Glad I could help matey, I'm only passing on things I've learned the hard way with my car. Hopefully you get to the bottom of it!

 

I have an MY99 @160k miles too.

For some time I had hesitation during off boost acceleration while engine was warming up and there were some large AFR correction values logged. Different lambda and MAF sensors, spark plugs made no difference. One day the car would not start and the fuel pump had gone. Once replaced the hesitation went away. I can only assume the fuel pump had been failing for a long time and fuel pressure was a little inconsistent and causing issues with the closed loop fuelling. If you are still on the original fuel pump it might be worth checking this as low fuel pressure could be fatal for your engine when on boost.

If you are logging then you can probably see if the boost itself is pulsing or whether the issue lies elsewhere. I thought that fuel cut on 99-00 cars is circa 1.2 bar.

 

This is another possibility, defo worth checking out. As far as the boost pressures and fuel cut goes, from what I have read it stayed the same for all the UK classics. Of course I could be wrong. I haven't had a chance to look at my standard map just yet. I'll do it today!

 

How do you check your own map, its deffo something i was looking at, id like to take the car to about 320bhp at some point anyway, so a new fuel pump will be needed, no reason why i can just do it early, why is bad fuel pressure bad for an engine? im guessing it runs lean, but why is this bad.

 

also if i had faulty lines wouldnt it over-boost constantly as a leak doesnt just fix itself.

 

I can check mine because I have an ESL ECU fitted. I can read and write the map.

The fuel pump just seems to wear out over time. I read that any impreza over a few years old should have the pump replaced as a matter of course.

Running lean can be catastrophic to the engine, especially turbo engines. It causes the combustion temperatures to rise and creates detonation or knock. Very very bad news for our engines.

With regard to the vac pipes, they may not be cracked but have became hard and do not seal properly around nipples etc. Temperature and movement would have a direct affect on how well they seal. This was the case for me. The pipe on the turbo compressor was not making a good seal and leaked under boost which got worse and worse as pressure rose further. An endless cycle! More pressure, more of a leak, more boost created until fuel cut!

 

Just to confirm, the fuel cut is set at 1.08bar on my UK turbo 2000 as standard.