Weird boost fluttering?

[Patryn999]

So, someone want to explain this one? :D Done it twice on the same corner now, but what happens is:

coming into corner (sharp 90 degree) so engine brake to 3rd, then second and stabilise de/accelleration to roughly neither of each, then halfway around the corner plant it straight to the floor. Kinda feels a little like FC, but not as violent and boost flutters around 5psi until you take your foot off and give it another plant.

Just curious as to what happened :S haha. Also with a MBC is 4-5psi of overshoot normal?

Thanks everyone!
Carl.

[Subaru ETA]

eerrr thats a new one!! it does sound like its hitting fuel cut. turn the boost down a coupld of clicks and give it a go. also try checking all the intercooler piping

[taupodrifta]

how much gas is in your car when your doing this cause to me it sounds like fuel surge meaning whent your half way round the corner the fuel pump is not picking and fuel and causing air in the system causing a hiccup which would also feel like fuel cut

[Patryn999]

Bam. that would be it - it was running on empty both times, and it only ever did it on the left hand corner.

Think this might be it, I'll check the piping thou too.

Thanks!

[elnevio]

Sounds like it then!

4-5 psi of boost overshoot does sound a bit much, by the way.

[Subaru ETA]

lol i obviously never got it that low on fuel!

it will spike 4 - 5psi when its cold, always has done since its had the exhaust fitted. even without the boost controller

[Patryn999]

Yeah, filled up tank and the same corner had no problems. Now I know what I can do (ish) on a tank (not much) lets not do that again... haha.

By cold you mean air or engine temp? Cause engines warm, but chch isnt! Also its 3-4psi so thats about what I expected. I blame the figures on these glasses I wear :P

[Wodjno]

Sounds like TCL cutting in ! Have you got TCL ? Or as above LOW FUEL.. /yes

[Davezj]

i was thinking Traction control as well, but if you have proved it was the fuel then you can ignore the rest of this post.

as long as you know you have traction control (pre facelift car) to test it you just have to go into the corner and plant your foot to the floor after you load up the suspension , the TC will back off the power and will stop you accelerating off the road and when the TC senses more grip (using steering angle, G sensor, yaw sensor, ABS sensors) then the power comes back.

it is a very odd sensation but you get used to it. it is much nicer feeling with TC off, but then you have to meter the power in to get round the corner safely.

[Wodjno]

To make sure it's not TCL. Try the same with it switched off /yes

[Gowf]

To be fair it sounds exactly like what mine does. Although mine is surge from the turbos fighting each other, sounds a bit like a steam train, due to the actuators not being truly balanced. However, if its only doing it on corners then it is definately fuel surge causing starvation which then leads to unequal fueling in each bank and thus boost surge. If that makes sense

[kiteman]

Maybe its a combination of TCL + low fuel

[Patryn999]

Its Dave (Subaru ETA's) old VR4, a 1997 pfl galant. I do not think it has TCL, it does not have the tell-tale switch and I have stepped the back end out a couple of times around sharp corners, but only just!

I'll keep the thread updated with my findings ;) pretty sure it was a fueling issue, so if anyone's reading this at a latter date - don't run on empty!

[wintertidenz]

His old car is manual, hence no TCL.

[Subaru ETA]

It's a manual so it does not have traction control.
And I was meaning air temp - I figured it was cold down there!

[djb160]

Bloody isn't cold today. Is there anything distinctive about your car so we can keep an eye out for you? What BOV,wheels, etc

[Subaru ETA]

it has a Club VR4 number plate surround so that should make it easy to spot :p

[Patryn999]

I've paid my dues, just waiting on the confirmation ;) Also think it'd be worth putting in an EBC (like the HDi closed loop SBC) to smooth over the boost spike (and thus get it higher!). Or lower to save a little on gas :S Only thing more astounding than the cars power is the gas consumption when you boot it!

Tossing up whether or not to do that or just talk nicely to see if any1 in chch has remapped the ECU and pay a bit down that field.

So many options, so little money... sigh.

But yeah, nice pearl-white galant, lowered. Kind if looks like Dave's old galant... surprise that :P

[Subaru ETA]

lol if you want to save on gas put a recirc BOV back in it. my one shat itself so i got that VTA one off mike (mpau). it was ok on fuel consumption but the extra boost blew the factory BOV apart :p

keep in mind too - at the auckland dyno day it did about 185kw ATW. that was less then a kw then williams if i remember correctly. his is a manual facelift with a after market front mount and a $1000 ebc!

[Patryn999]

That would explain the car's gut wrenching launch :P haha. Yeah, but I've got to do something! cars not truly mine till its had a touch of tinkering.... Just make sure I think any changes through so that it isn't a step back.

[Subaru ETA]

if it were me, which it isnt coz it not my car anymore, i would be upgrading the fuel pump before you try to get anymore power out of it. i think it is pretty much getting to its power limit with the factory fuel pump.

that was going to be the next thing i was going to do to it

[Patryn999]

I'll take your advice. I was tossing up between EBC, larger FMIC or fuel pump. Currently just powering through reading the posts to get some idea on what to expect/do/generally gathering knowledge.

Give me 6 months and I should have all three, just the order of it! Assuming something doesn't got catastrophically wrong.

Then I've got to think, do I really need more power? :P Got to have some sort of hobby.

EDIT: Also, how much of a benefit to fuel economy are we talking about here? probably sink ~200 into a recirc BOV?

[Subaru ETA]

it would get about 400km to a tank running the boost it is and about 450km on standard boost.

at the moment around town driving its probably getting about 350km? i dont really know coz im only a 3 minute drive from work so it was only doing short trips. that said i stopped using it on a daily basis at the begining of the year and jess has been driving it