Flutter and boost fluctuations at max boost

DaveSleggy

DaveSleggy

Well-known member
So iv a bug STi and recently fitted a RCM trumpet induction kit. It hasnt been mapped in yet, but i spoke to the mapper (Aungus) and he said its fine to run the car with the kit it wont blow up just wont be optimised to run with that set up.

So i did a run on the motorway at the weekend and was doing some spirited overtaking in 6th gear (doing 120kmph never exceeding 120kmph) and when the car hit peak boost, it was fluttering like crazy and rapidly fluctuating between 1.3 and 1.4 bar on the boost guage.

Queation is should i be worried?

is this normal with the increased airflow?

Should i have left the kit off untill mapping time?
 
Sound like boost creep

Had it myself recently

Can happen especially when it's cold and mabay Rcm affecting it to..nothing to really worry bout as newage ecu be pulling everything back.

I'd avoid 6 gear low rpm pulls till you get it mapped.

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It's not boost creep no , it's compressor surge , in 6th gear at that rpm at full boost the engine has trouble consuming the amount of air the turbo is providing . Simple solution, drop a gear.

This is why the factory air box works so well

This happens with higher boost levels , this is why you see big turbo with anti surge housings to prevent it .
 
It's happening to mine at the min and I was told the same as what baz just said I'll be taking it handy until it's mapped
 
Cheers lads that does make sense seen as no other gear seems to be affected. Il hopefully be getting it mapped in january so that will help, just need to sort out a sports/de cat between now and then. Did you hear back from icetronix keith?
 
It's happens mine aswell .
You need to get used to driving the car , if it annoys you that much bring her back down to factory boost levels .
It's not in anyway a mapping issue although it can be smoothed out by keeping the boost level down at the lower rpm where the surge occurs
 
I get it myself really doesn't like to be floored in 5th if I'm cruising along at 120 I can actually feel it struggling to cope with all the air it's taking in.
as Baz said drop a gear and it should be fine.


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Did it happen before you put the induction kit on? If not, then either take it off or drive it handy until its mapped properly. I know what aunghus said but unless you know 100% that the air fuel ratio are OK, then its an unnecessary risk imo.
 
Rob i dont know if it did but im imagining not, i think the factory airbox is a lot more restrictive and would prevent the surge.

This morning i had an interesting one i was pulling off a roundabout in 3rd or 4th at 2000revs and looked at the boost gauge and its sitting there at 1bar then i accelerated and it starts flying up to 2 bar! I thought this was strange seen as nothing had exploded under the bonnet and i wasnt hearing any mental turbo noise so i rolled up to the red light and while it usually sits at .4 or whatever in vaccum it was sitting at 1 bar.

So i switched the car off and then back on and the boost gauge did its normal self test thing where the lights come on and the needle goes full scale deflection and back and then back to normal.

Weird, could be a coincidence but seems strange? beginning to think maybe the factory air box should go on till mapping time.
 
There's a box mounted at the top of my brake peddle were the air line goes up to the gauge sometimes my gauge goes a bit mad and if I moved the wire or hose on it with my foot it settles down.have a look around your feet to see if it might be similar[emoji106]


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Good gauge . Same as I have .
Boost spike is what happened , try feed the power on more gradual until it's mapped
 
Well there was no change in power and no audible noise to indicate spool of any kind, i thought a line had come off or something, seemed the guage was getting bad signals rather than actual spiking in boost.
 
So it seems to be electrical, the cable going into the back when moved moves the needle around.

So I did a bit of rooting and traced it back to some controller that's just loose inside the steering colum shroud.

So when i moved that wore it eas moving the needle up the dial and it eventually stayed put at 1m5bar and i thnk the car wasn't running great (could have been my imagination).

Then I managed to reset it and it was grand. I took a few pics if anyone's got any ideas.uploadfromtaptalk1448382410653.jpguploadfromtaptalk1448382421119.jpguploadfromtaptalk1448382431544.jpguploadfromtaptalk1448382441619.jpg
 

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Did you refit the air box, if you're getting a fluttering on boost in 6th it nothing to do with a boost gauge wiring
 
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