classicscoob

iTrader: (1)

Got a bit of a problem with my MY99 UK Turbo, when ive been driving on the motorway for about 45mins at around 85mph and accelerate the turbo seems to surge, its not the clutch as the car still accelerates, and ive had a scooby with a clutch on the way out, but with this surging sound from the turbo.It doesnt do it in any of the other four gears,only in top. Ive got a sports cat, decat centre and h n s backbox with green filter. Ive just had my usual mechanic test and clean the pipework to the boost solenoid and run an ecu check and check the MAF, all fine. But i went out and hey presto it was still there. Im having a remap in September, could this cure it or am i missing something, help!

500

Remap will sort it, its down to the decat if the boost control soleniod is clean.

ClintUK

Surge is when you get pumping acceleration, can't see how you'd think it was a clutch problem (thats lack of it)

I had a shocking case albeit with non standard turbo, basically exhaust wasn't flowing enough to keep the compressor spinning, so there's an increase in exhaust pressure to a point where turbo spins more, but then there's not enough pressure to keep it going.

Maybe your exhaust mods have done this as you haven't had remap to suit - make sure you have a 3 port boost solenoid for the re-map and if you're sticking to same turbo I'm sure it'll sort it out.

Probably only noticable in top as engine revs therefore exhaust volume changes more slowly. It's a tad more complex of course but hey...

Are you getting overboost at all? Often that's what people complain about before a remap. if so be gentle till mapping is done.

classicscoob

iTrader: (1)

Thankyou for replying, i dont think it is overboosting,but your explanation seems to make sense.Im not the most technically minded person but could you explain more about why its only doing it in top? I hope the remap does sort it out,i realise i should of had the remap sooner to set the car up with the mods, this three way boost solenoid you mention, do i really need to get one? The surge really is a sound, like the turbo is going up and down, i apologise, it doesnt kangaroo.Is this common?

simonds1

Hello mate, my turbo seems to whistle up quite high.....then settle back down to a constant noise.....is that the 'surge' ur talking about? I don't think it's a problem, but not sure. Like if I'm in 5th on the motorway and decide I wanna overtake, I put my foot down a bit and the turbo whistles up....then drops down and settles sorta thing

classicscoob

iTrader: (1)

Its like that mate, but seems to go up and down in noise but it still accelerates okay,im hoping the remap sorts this out, fingers crossed

classicscoob

iTrader: (1)

Just one more question and ill stop bugging everyone with this thread, will the remap sort this, it sounds like my turbo is going up and down, but i dont see any real difference in acceleration, i think im too much of a perfectionist with my scoob,someone just put me out of my misery and stop me worrying!

classicscoob

iTrader: (1)

Anyone?

ClintUK

Right - it doesn't actually sound like turbo 'surge'.

Surge feels just like that, when you plant your foot you get strong acceleration that weakens then surges back again and so on ie it's not smooth.

What I think you're describing is just noise, ie turbo whistle.

All turbos do this to a greater or lesser degree, basically a turbo is 2 fans 1 being spun by the exhaust and 1 pulling more air into the engine. Fans make noise.

These turbos can spin at over 100 000rpm, but will be going much slower than this off boost.

So when you accelerate say from 70 - 90 in top, you will have been sitting off boost waiting for the car in front to get out the way. When you accelerate the ECU and other magic gubbins close the wastegate in the turbo and the turbo accelerates from say 10 000rpm to 100 000rpm. Big numbers so it's not surprising there's a bit of noise.

Unless your going on to reach terminal velocity at 140mph+ you'll lift the accelerator and your engine's now running without as much boost so there's no need for it to be spinning like a mad thing.


Different turbos make more noise than others. I have a modified one and when it's cold it really whistles - in fact I can play it like a tombone

It's likely yours does make the same noise in all gears if you have similar engine loads and engine speeds. It's nothing to worry about, but a remap will not get rid of the noise, in fact you'll probably hear it lower in the rev range as getting the turbo to spool up (accelerate in rpm) at lower revs is what you want.

(I've simplified matters a bit, but i don't think I've lied )

classicscoob

iTrader: (1)

Thankyou mate, youve put my mind at rest