94 Jap Impreza overboost? Urgently need help please!
 

I have a low milage Jap Import Subaru Impreza WRX Sport wagen my94.
When I got the car it came with a full scooby sport exhaust system (not just back box).
The car performed and sounded superb!
I only use Optimax fuel and invest in the best oil.
I added a Bailey dump valve and everything was sweeter than ever!
I ran this setup for almost a year without any issues at all.
I then added a bleed valve and my boost was alot better giving me 16 psi without any issues.
Around five months later I decided to add another mod.
I had a HKS superpower flow added!
This made the car sound even more awesome and gave some extra performance!
Then I noticed a fault.
I found that if I hard accelared through the gears when I got to about 100mph the boost went to around 18psi and I got
what seemed to be an air issue.The car would lose itself for a second almost like a filter was blocked.
This only occured on freezy cold nights and would not happened if my foot wasnt to the floor on the accelerator.
I then decided that more power was needed!
I then found that my Bailey boost had given up on life!
I replaced it with a much more powerful one that can take higher boost than the car will run.
Some month later my fuel pump needed replacing.
I still had the 100mph problem but all was cool apart from this!
I added a HKS EVC IV.
Now the real problems started!
I set everything up to the instructions.
Low boost was set to 0.55 and I have tried high/max boost on more or less every config ranging from 1.2 bar to just 0.60 bar.
what I find is that the boost is raising much much faster than ever (Im sure the cold temps at the moment dont help!) and the boost gauge goes way past 20psi very

quickly if I accelerate with the pedal to the floor.Once in this zone the car cuts out for a second which is far more violent that the air issues that were occuring before.I

understand this is the engine/turbo protection coming in!
The rev counter/engine cannot keep up and I find myself changing gears extremely quickly just to stop the overboost!

Any help and advice in regard to this would be very much appreciated!
It is driving me mad!
I cant drive this superb car the way it was designed!

fcd
 

your car is hitting the fuel cut off because of the amount of boost u r running u need a fuel cut defencer , but becarful not to wind up the boost up to much more or you will go pop!!!!!!!!!!!!! I have a low milage Jap Import 100mph the boost went to around 18psi and I got
what seemed to be an air issue.The car would lose itself for a second almost like a filter was blocked.
This only occured on freezy cold nights and would not happened if my foot wasnt to the floor on the accelerator.
I then decided that more power was needed!
I then found that my Bailey boost had given up on life!
I replaced it with a much more powerful one that can take higher boost than the car will run.
Some month later my fuel pump needed replacing.
I still had the 100mph problem but all was cool apart from this!
I added a HKS EVC IV.
Now the real problems started!
I set everything up to the instructions.
Low boost was set to 0.55 and I have tried high/max boost on more or less every config ranging from 1.2 bar to just 0.60 bar.
what I find is that the boost is raising much much faster than ever (Im sure the cold temps at the moment dont help!) and the boost gauge goes way past 20psi very

quickly if I accelerate with the pedal to the floor.Once in this zone the car cuts out for a second which is far more violent that the air issues that were occuring before.I

understand this is the engine/turbo protection coming in!
The rev counter/engine cannot keep up and I find myself changing gears extremely quickly just to stop the overboost!

Any help and advice in regard to this would be very much appreciated!
It is driving me mad!
I cant drive this superb car the way it was designed![/QUOTE]

I have the exact same problem with my 94 wrx import with the same boost controller, it boosts brilliant but as soon as it hits full boost the controller says overboost and cuts the boost back any ideas ?????

try re plumbing the original boost controller back in properly and see if you still get the problem, it sounds to me like there is a leak in the system somewhere and you are hitting fuel cut, which can be quite violent someimes, to the first poster, i would get this sorted before driving it hard, its a very very easy way to kill the engine, very quickly.
I have a 94 wrx import and i have had no problems at all with overboosting, although i dont use an electronic boost controller. ;)
In all seriousness though, you are into engine killing territory now, especially with over boost to 20 psi, you wil be lucky if you injectors can keep up with that, and if they cant its melted piston time, at the very least.

Take of the controller, re-plumb as standard and get a chip of Scott.t at polarperformance.
The wagon is iirc only running a td04 and will not like too much boost, the standard boost/fuel cut on your ecu is 14.7 psi/1.02 bar,

18psi=1.24 bar
20psi=1.37 bar far too much!! :brickwall

Scott.T chip will take you to 1.1 bar which is plenty imo for a iccle td04.
you could if you really wanted too, after you have installed the chip set the MBC to 1.1 bar this will bring the boost on quicker but still leave you safe, well as safe as you can be after you have by-passed subaru's safty settings :brickwall :confused: :freak3:

Other option ESL board also from polarperformance, a little more ££££ but cheaper than a re-build :cry: :D

Hi all.

Ive got another MY98 model saloon version, and the TD04 certainly doesnt like Exessive boost.

The last one i had was modified a fair bit, and in the beginning I was hitting the Fuel cut hard (feels like a brick wall!!)

After an Apexi FC, Front mount, Devils Own alcohol inj. System, 3" straight thru (decat) Walbro pump and some deftly tweaking by Paul at Zen Performance, the car ran really good.

Paul stated that 290bhp is probably the limitation for the TD04 whizzy, even with uprated injectors ect.

Now i have this second nearly standard scoob, Im getting a touch of what i think is fuel cut, as the boost guage is hitting about the 1.1bar on hard accel.

Ive checked to see if the restrictor pill is still in place (and in the right side!!:brickwall) and all the hoses seem to be ok. Its only running a K&N, and a Janspeed centercat back pipework system, so i cant see why it would overboost. It doesnt do it if you dont put the pedal to the metal, and i see about 1 bar on the guage.

Im seriously thinking about either:
1: fitting a manual boost controller and winding the boost down a bit, (not needing more power, want it a std as possible)
or
2: removing the Pill and seeing if the boost solenoid allows the wastegate to shut earlier.

What do you guys think?

the exhaust and filter might be helping with the over boost, however, it might be worth having a look inside the ecu and seeing if there is another board on there, an esl or daughterboard that is 'remapping' the boost settings.

failing that, you could put the standard bits back on and see if you still have the problem.

The waste gate would have to open earlier to give less boost:thumb:

Quick Update on my fix. May help others on this version.
1st, Thanks Baz, youre right I typed that complely wrong!!! OPEN for the bypass of gasses!! LOL!!!

Basically this scooby has been lightly modified with a simple K&N cone filter and a cat back exhaust as stated before.

To recap, under HARD accel. the boost cut came in (about 1.1-1.2bar)

Today I have managed to fix the problem with a little trial and error. The original pill was removed and measures 1.2mm hole.
I made a new restrictor pill from brass with a 1.3mm hole.

Now she boosts to about .95 bar and hits 1 bar in top end gears, and no more fuel cut. Simple fix without loads of money, and saves the engine as well.

Bear in mind, the amount of overboost will change the size of hole needed in the pill to fix the problem. **I have only tested this on the 2 port models, with pill in the inlet-to-wastegate pipework, in the inlet side**

Was gonna say resistor pill. I had same problem when i fitted my bleed valve. didnt know back then that they where in the boost pipes.

Glad ytou sorted it and it was a cheap fix.