Speccy D

I was out driving this morning and the car did something really weird.

I took a tight right hander and then accelerated hard as I hit 6000rpm it suddenly just stopped accelerating, like hitting a rev limiter and at the same time a bang/mis fire occured from the engine and according to the car behind me s short puff of black smoke came out of the exhaust.

it's driving fine now, turbo works, no loss of acceleration, no strange noisey. It has done this about 3-4 times in the 7 months i have owned it. always at 6000rpm and always in 2nd gear on a tight bend.

I did have a problem with the engine warning light coming on code "p04020 cat/02 sensor wiring" recently, the dealer had a look couldn't see anything wrong and re-set it.

Any ideas on the likely cause?

car is 03 sti prodrive with JGM remap

TonyBurns

iTrader: (3)

Fuel surge?

Tony

Speccy D

It has quite a sooty exhaust which now has some kind of white residue on the bottom part of the tip. Could just be co-incidental.

Would a fuel surge momentarily cut the fueling? Sorry mechanically I'm not that knowledgeable. When I mentioned this to the mechanic checking the engine light at the subaru garage he thought it might have been the fuel pump cutting out.

mr_D

iTrader: (12)

fuel surge or overboost by the sounds of it

alcazar

iTrader: (2)

Another vote for fuel surge. Classic symptoms.

Speccy D

Thanks for the suggestions. Is there any way to stop fuel surge happening apart from tippy toeing round corners? Does it do any damage to the engine when it happens? Should I try and keep my tank brimmed higher? it was at or just below a 1/4 when it happened.

pooeater

fuel surge mines done it 2, your fuel pickup bag is on the righthand side of the tank so going around righthanders with less that 1/2 tank of fuel (fuel starvation) and can melt a piston i think? i try and keep mine topped up

Speccy D

Would I know if i had melted a piston/ring? It did make a bang/pop at the time

alcazar

iTrader: (2)

You'd know

Keep it topped up, or keep your foot off a bit

GC8

Ideally you need a baffled tank, or better still, a swirl pot; so that the fuel is being drawn from a buffer, as opposed to direct from the tank (both ideally).

The best way to prevent surge like this is to fill your tank with foam. Its usually supplied in one gallon sized pieces which you force into the fuel tank. Its far from cheap though, at about £10 per gallon, but far less costly than a new piston or a big end bearing.

Simon

MaDaSS

Foam??? Tell me more???

MK2VTR8VALVE

I think I've suffered this a few time before as well. Especially coming through a roundabout hard.

zakscooby1

iTrader: (8)

i would go with swirl pot as its hard keeping a full tank in all the time lol,am i right in saying you would need a low pressure fuel pump for the swirl pot?

GC8

http://www.demon-tweeks.co.uk/Store/...m/1545/0/23208

You can also buy 80mm x 80mm x 80mm cubes for about £1 each from Merlin Motorsport (this equates to about £9 per gallon).

A bit of work will find this stuff for less money, but not that much less as its fairly specialised.

Simon

jonny_693

iTrader: (5)

Wouldn't that pretty much render the fuel gauge useless. Espiecially if the foam is wedged against the sender unit?

DJ_Jon

iTrader: (7)

I've had the same thing happen on my old Classic when the fuel was low. Keep it above half way & you should reduce the chances of it happening again.

GC8

The sender is a float on an arm in a 10 gallon plastic speedboat fuel tank I have - but theyre a little more advanced in cars! Itll be in a tube and itll sill work perfectly well.

D1CCY

Used to use my 03STi for track days (now for sale, stripped caged and masses of toys). Always made a point of keeping at least 1/2 tank of fuel in it and never had any probs. Depends on how long the right handers are, never done Mallory (yet) but there is a killer long right hander there where 1/2 tank of fuel may not be enough and a proper swirl pot would be the only safe option.