I've only launched a couple of times now, but both times when I hit 3rd gear and get around 130kmph (82 MPH) I get a sudden loss of power. I'm reluctant to do it again.

(Series 4 turbo 2) Any Ideas?

 

Boost leak maybe?? Check couplers on intercooler hoses, they may be loosening or something under high boost. Check for cracks also.

 

Another possibility might be (thought about this as I've been giving lots of thought to FCD lately) is that in high third gear your reaching a boost level that is triggering the Fuel-Cut by overboosting.

Do you have any mods? Have you ported your wastegate to keep from getting turbo-creep??

zub

 

There is a full 3" exhaust but that's it for performance mods.

turbo-creep??? Sorry I'm a newbie and I have not heard this before

 

ouch that whats happening your hitting the fuel cut at 8.6 psi don't do it anymore or you rish blowing your engine, buy a RB fuel cut defender, only 50 bux good investment if you have the fuel..............

 

sounds like fuel cut. do you have an aftermarket boost gauge? I bet you are boosting too high.

 

Be sure your fuel system can handle the extra boost from the FCD. You hit fuel cut for a reason, to keep you from leaning out and blowing your motor. Upgrade your injectors and get some sort of fuel controler to handle them.

 

Exhaust mods have a major impact on our cars since backpressure directly slows the rotors.

By placing a larger exhaust on the car you've allowed for a much larger volume of air to flow through the turbos.

Generally you won't reach full boost until 2nd or 3rd anyways....but in your case you're not only reaching full boost but may be "creep"ing above that level.

This is happening because the the wastegate is still opening at the correct relief pressure but the wastegate is no longer big enough to bleed off the larger volume of air you're passing through your exhaust.

Do some searches for porting wastegate and boost creep, zenki turbo. At the very least do like others have said and get or build your own FCD (for building one see sticky at beginning of 2nd gen forum).

When you're losing power it's because the ECU is cutting off all fuel to the rear rotor....read BAD.

Glad to have been able to help an Aussie.....can't wait till I can get down there again

Good luck

zub

 

Thanks guys,

This might be a stupid question but when installing a FCD don't you need to adjust your air/fuel mix or does it run rich enough not to worry about it?

 

The correct answer is yes you need to adjust your mixture. Realistically though my thought is that some fuel and running a little lean is better than no fuel at fuel cut.

I would suggest getting an aftermarket boost gauge though so you can see just how much boost your getting. If you're creeping you may be getting enough boost to damage the engine. If you're under some boost level "X" you're probably still ok.

What's "X" you ask.......I don't have a clue. Hailers may as he's been looking at air/fuel in relation to boost with FCD installed. I would guess 10psi or so wouls still be ok as it's not that much higher than stock but with every psi higher you're running leaner and tipping the odds against you.

 

Thanks Zub,

For safety sake would it be best to install a FCD with a boost controller set to 9psi?

 

You cant lower your boost with a boost controller, it can only raise it. They best way to keep your boost at a safe level would be to port your wastegate.

 

I think that would be great. Problem I have with that scenario is I don't think we're sure that you're not experiencing boost creep. A boost controller is not going to eliminate creep, all it will do is allow you to increase boost. You need to determine if you are experiencing creep for sure. Aftermarket guage or some other means.

If you are experiencing creep......which seems likely given your only performance mod is the exhaust then you're going to have to combat the creep to save the engine. If you don't get rid of the creep your on the short road to engine failure.

S4 turbos only had 1 wastegate and it apparently wasn't able to keep up. Port the wastegate, get an S5 or aftermarket turbo set-up, or put in a pop off valve(don't know much about that one) are some of the ways to save the engine by keeping your boost from getting to high.

If anybody knows better or if I screwed something up please correct me........just trying to help and don't want to feed any disinformation.

zub

 

Thanks Zub, I'll fit the gauge soon.