WRX101

I think I need a fuel cut defender for my 03 WRX but dont know for sure, so if any of you can help it would be much appreciated.

I have the following modifications to my car: 1 cat removed, mid section exhaust and back box replaced, HKS dump valve, panel air filter. Everything els is standard.

Now when I drive in the turbo I'm getting a sudden loss of power, like its bogging or someones just tapped the brakes, the power just isn't there. A FCD sounds like the answer but from what I've read it can cause damage in some cases. I have a bit of a tight budget at the moment so can't go doing any major ECU remaps but obviously don't want to damage my engine. What is involved with the FCD and what steps should be taken when fitting one and are there any other modifications that need to be done at the same time as the FCD is fitted?

Thanks in advance for your help.

saiklon

If you need an FCD, then the car is overboosting. Connect a boost gauge to the car and check the boost when it happens. If it is fuel cut, you will notice it more often in the higher gears and it probably won't even happen in gear 1 and 2. And fuel cut is also very repeatable not intermittent.

If the problem is indeed overboost, then you can have your boost solenoid and wastegate actuator checked for proper operation.

Fitting an FCD would merely allow your car to operate far outside its design parameters; increaing the likelihood of engine damage. The solution is to regain control of the boost.

WRX101

Saiklon: I first noticed it when driving in fourth and fifth gear. Like you say it is more noticeable in 3rd, 4th and 5th but does seem now to be doing it in lower gears too if really giving it some beans. I don't know why it should be overboosting. I first noticed the problem about a year ago, long before i fitted the dump valve but it went away on its own. I've had the dump valve on about 3 months now and its started up again but is now doing it pretty much perminantly. I'm not too keen to increase the boost at the moment anyway, I would just like it to run properly how it should.
What do you suggest if not a FCD?

saiklon

First get a boost gauge. It will tell you how much boost you're running. I'm not sure how high fuel cut is for your car but it should be above 1 bar.

After fitting the gauge you will know for sure that it is boost cut. For example for a MY95 WRX, fuel cut happens after being at 1.1bar for at least a second and stays on till the manifold goes back to negative pressure.

You could fit a boost controller but many people on Scoobynet advise not to fit one on a newage.

Check and clean the boost solenoid first, check that you still have the restrictor in the correct pipe to the boost solenoid (it comes off the intake somewhere between the airbox and turbo). Check that your wastegate actuator can move freely too.

WRX101

Ok, so should cleaning the boost solenoid and checking the wastegate actuator can move freely completely solve the problem or even if all that is fine, could it still be overboosting? then what?
I'm a bit of a newbie when it comes to turbo engines.
How big a job is the above, to do?

dan83590

The mods you have will have eased air flow restrictions so the turbo will spool more freely, this may be your problem.

WRX101

Hmm, sounds like it could be a few different things I'm pretty sure its overboosting though so need to fix that. It's due for its service at Subaru so I'll get them to try and fix it at the same time.