I almost $#@!ed in my pants!

I bought my MKIV completely standard and I am 99% sure that it never had a Fuel Cut defender or BCC installed.

The only mod it has is a RMM downpipe and a HKS super Dragger Cat-back.

Yesterday I installed a boost gauge. And when I floored it the gauge showed 1bar. And I thought shouldnt It fuel cut before 1bar!? Then I took it out on the highway, and I floored it again(unfortunately I didnt look at the boost gauge).

The Defi boost gauge went "BEEP" and then I almost crapped my pants.

I didnt see what the boost gauge was showing but I didnt like the sound from the Defi gauge.

Can somebody help me, I don't want my turbos blown! I hope it is the boost gauge reading wrong..

Its a US-spec running 99 octan.

Do it again and have a look at the boost gauge. If it goes past 1.2 then you definitely need a restrictor ring and you definitely have some kind of FCD.

You will know if you hit fuel cut.

Fuel cut is a horrible thing to experience, it is like your engine is trying to rip itself from the car.

Fuel cut happens if you go over 1 bar for 2-3 seconds. Make sure you have everything for BPU.

I can boost 1bar all day long no fuel cut... I will try what u are suggesting Scotster..

But I only have a downpipe and a catback system installed, 1 bar shouldnt be capabel with only this mod? or could it?

Thanks!

You will know if you hit fuel cut.

 

Fuel cut is a horrible thing to experience, it is like your engine is trying to rip itself from the car.

 

Fuel cut happens if you go over 1 bar for 2-3 seconds. Make sure you have everything for BPU.

I thought something had blown when I hit fuel cut, it's a very nasty thing indeed. I only had the second cat out at the time, but it was in the middle of winter.

Do anybody know what the Defi Boost gauge warning is set to from start?

I can boost 1bar all day long no fuel cut... I will try what u are suggesting Scotster..

But I only have a downpipe and a catback system installed, 1 bar shouldnt be capabel with only this mod? or could it?

 

Thanks!

Yes it can definitely happen, well... if the US is the same as the J-Spec which i believe it is.

On the J-Spec supra's the only thing holding the turbo back from winding up to its max is the downpipe due to the restriction. Its all down to a wrongly sized wastegate. The UK versions have a bigger wastegate so they can let the excess boost out before winding up the turbo. As soon as you add a de-cat pipe you are doing away with this restriction allowing the turbo to "breathe more easily" meaning it will be able to spin faster and free'er. The faster the turbo gets the more heat generated and the more danger of extremely high EGT's and ceramic explosions. A restriction ring is fitted after the first de-cat to restrict the flow and keep the turbo running within its optimum range. Its usually a good idea to have it running around 1bar using the restrictor ring and wind up the boost to 1.2 using a boost controller.

1.2 is seen as the absolute maximum for J-Spec's to run safely. Normally you will only see this boost under maximum load so from 3rd gear on. Of course this means you will be over the limit so make sure you are on a very quiet, straight and dry road as you will need to take your eyes off it for a brief second to check the gauge.

If your Défi is running through the Link system, press the peak button when you're not moving to see your maximum recorded boost.

Otherwise, press the record button before you test it and press playback when you've come to a stop.

I know it is stupid, but I did hide my control unit, behind the dash.. Didnt thought I would need the peak/record/warning things. So if somebody could give me the stock warning setting, I would be happy.

Check you haven't blown a pipe off the wastegate vsv. It'll take you about 30secs to sort it out.

If this is what's happening, the wastegate won't be operating and your boost be uncontrolled. (Which is BAD)

if you want it to run stock, which is 0.9, then you will need a restrictor ring set for 0.8 and a boost controller to raise it.

Perhaps its better to tell us what you actually want from the car boost wise before we give any advice. I just assumed you wanted the best potential out of your car. You should have just kept the cat in if you want stock boost.

I want to run it safe... Max 1.2 bar.. But I don't want it to boost more than that.. Thats why I'm afraid:(

Yes it can definitely happen, well... if the US is the same as the J-Spec which i believe it is.

It isn't. UK/US/Export Spec are all steel bladed turbo's, and do not need a restrictor ring.

if you want it to run stock, which is 0.9, then you will need a restrictor ring set for 0.8 and a boost controller to raise it.

Stock boost isn't 0.9

He's no need for a restrictor ring, but he will need some form of boost controller to raise the boost to 1.2

It isn't. UK/US/Export Spec are all steel bladed turbo's, and do not need a restrictor ring.

 

 

 

Stock boost isn't 0.9

 

He's no need for a restrictor ring, but he will need some form of boost controller to raise the boost to 1.2

M8 I dont want to raise it, I'm just afraid it will over boost(1.2bar+) if I floor it again,.. I didnt experience fuel cut at 1bar :S.. And I have been told that a Boost controller can't lower boost anyway:( I just heard my defi gauge warn, and I stopped. I dont know at what pressure the defi gauge will beep warn. I havent touched it.

M8 I dont want to raise it, I'm just afraid it will over boost(1.2bar+) if I floor it again,.. I didnt experience fuel cut at 1bar :S.. And I have been told that a Boost controller can't lower boost anyway:( I just heard my defi gauge warn, and I stopped. I dont know at what pressure the defi gauge will beep warn. I havent touched it.

Either there is something controlling the boost on your car or the wastegate VSV is off as mentioned before.

You need to help us to help you by investigating our suggestions

I would take the car out for a spin and see where it boosts to in 3rd. If it goes past 1.2bar simply, and gently, let off the throttle. This would mean that its most likely nothing is controlling the boost and the wastegate is not opening correctly. If it boosts to 1.2bar and holds steady then there is a boost controller on the car holding it at that boost and all you need to do is re-set your boost gauge limit warning.

M8 I dont want to raise it, I'm just afraid it will over boost(1.2bar+) if I floor it again

Well you just need to go out in it again and watch the boost gauge and let us know what exactly you're hitting. If you're regularly hitting 1bar then it could just be that in higher gears or colder weather you're hitting slightly more than that and triggering a warning alarm on your gauge.

Well you just need to go out in it again and watch the boost gauge and let us know what exactly you're hitting. If you're regularly hitting 1bar then it could just be that in higher gears or colder weather you're hitting slightly more than that and triggering a warning alarm on your gauge.

OK thanks guys, I will let you know later when I watched the gauge..

I know it is stupid, but I did hide my control unit, behind the dash.. Didnt thought I would need the peak/record/warning things. So if somebody could give me the stock warning setting, I would be happy.

Would it not be easier to remove the control unit from where you put it and press the button to watch it back? i am sure it would only take 5-1o minutes to do then your mind would be at rest.

If your Défi is running through the Link system, press the peak button when you're not moving to see your maximum recorded boost.

 

Otherwise, press the record button before you test it and press playback when you've come to a stop.

I did this on mine the other day and saw 1.5 bar

never normaly boosts past 1.3 though

1.5 bar on stock UK/US twins :O?

Something wrong there buddy. Sounds like the wastegate is malfunctioning somehow.

1.5 bar on stock UK/US twins :O?

must have just been a one off on a very cold day. i dont run a RR or a boost controller so it boosts to whatever it feels like.

Do anybody know what the Defi Boost gauge warning is set to from start?

The default warning limit is 1bar, press the warn set button on the controller to view what the warning is set to. You can also press the peak button to show what the peak reading was.

Thanks Nic!

Something wrong there buddy. Sounds like the wastegate is malfunctioning somehow.

Why do you always seem to assume the worst?

must have just been a one off on a very cold day. i dont run a RR or a boost controller so it boosts to whatever it feels like.

I'd fit a RR if I were you.