Hi,

I have a 1994 WRX 2.0L Turbo import. It runs great up untill I run boost over 16 psi. It then boosts out and looses all pull. Any ideas on what the problem is?

Thanks for any help or advice you can give me.

 

Overboosting and hitting fuel cut. Presuming your running a standard map and using a manuel boost controller, if best thing to do is chuck it in the bin.

 

I am using the standard map. But not using a manual boost controller.

How do I solve this problem then?

 

How are you achieving 16psi? it shouldn't be boosting that high standard. that is where the problem lies.

 

I thought normal boost was about that. And I've read about it hitting fuel cut. I just want to be able to boost without feathering the accelerator.

Ever came accross this before?

 

Normal boost should be around 11psi iirc, certainly no where near 16. The fuel cut is enabled at 16psi to prevent engine damage.
If it is boosting to 16psi and there is no aftermarket boost controller fitted, then it can be caused by a few different things. the most common causes are insecure or split/holed pipework, the turbo to intercooler hose is notoriously bad, also any of the small bore vacuum pipework.
Also check the turbo actuator is free and not jamming.

Has it just started happening? Is there any mods on your car?

 

16 PSI is approx. 1.1 bar, IIRC normal boost on the TD05 I assume your car has is circa 0.9 bar or 13-ish PSI.

 

My car has NO manual boost controller and I'm fairly certain its not been mapped.
1994 Impreza WRX 2.0L Turbo (GC8 EJ20) import
It has a standard top mount intercooler, high flow 42mm thick aluminium radiator, hight flow stainless manifold, straight thru 3" de-cat down pipe & 3" thru to back, Apexi induction with green cotton high flow filter and has had a full service (sparks, coil packs, fluids & filters).

And I'm pretty sure its a TD05 but I will check just to make sure.

It's been doing it since I bought it 6 month ago.

 

The first thing that jumped out at me there is the 3" exhaust, if it is a true 3" without a 2.5" taper it will require a different from standard restrictor pill in the turbo solenoid. But lets not jump to conclusions just yet as it may have been done.

First off you need to make sure there is no boost leaks on the pipework, listen under the bonnet for any hissing while the engine is idling, and check all pipes are secure.

Check the boost controller itself is working, you should here it clicking while the engine is ticking over (it's attached to the drivers side suspension turret)

Check the turbo wastegate is not seized, you should be able to move the actuator (although not by hand) It takes a bit of force to move and is easier with a lever

Any of the above could prevent the wastegate opening to regulate the pressure.

 

Just checked and the exhaust narrows from a 3" bell mouth to a 2.5" pipe in the decat down pipe and runs a t 2.5" from there on.

I'm gona sit and try out the other sugestions that you've gave me tho. I will let you know how it goes.

By 'boost controller' do you mean the solenoid? Because that is whats on the direvers side suspension turret.

 

I'd think it would be the restrictor pill...

 

fuel cut,eh? i think that's what happened to me whilst racing that RS4....but the cut stayed there the next day and from there onwards, untill i put the stock map back on.

 

Is the retrictor pill the plastic reduction sits in the solenoid to actuator line?

 

If you have a 3 port bcs the restrictor should be inside the bottom pipe which goes to the air intake. Try running a pipe straight off the turbo to the actuator this should make it run about 7psi.

 

So I'm guessing that the wastegate opens at around 7psi normally then?
What sort of pressure should I be expecting to run with a fully functioning boost system?

Yeah my car has a 3 ports bcs. The bottom pipe runs straight back into my air intake. And I'm gona remove the reducer from the solenoid-actuator line.

I'm gona just have a good look over all the pipes and replace anything that looks suspect. And ensure that my actuator/wastegate is free as well as giving the solenoid and any apropriate pipe work is checked and cleaned out.

If that doesn't work then I'm back to square one.