Andrewj

MY99 Turbo. No Mods.

I get a bit of hesitancy at about 4000 rpm in each gear, but it then clears when the revs rise towards and past 5000.

Is this turbo lag, a "flat spot", or what?

Its going in for its 60,000 mile service in a few weeks so I should be able to get it sorted.

Thanks for your views.

AJ.

Aintbroke dontfix

Get them to check your MAF & Lambada, This doesn't sound like lag as turbo should be well on song by then. On this model lag only factors below 3200rpm I think.

TonyBurns

iTrader: (3)

Ah the common misconception about turbo lag
What your suffering sounds like a flat spot, turbo lag itself is more promenant when changing gears, the pause between the dumping of gasses and the gasses coming back though to the turbo is the lag.
On smaller turbo's this isnt much of a problem (you dont really notice it that much) and there is no real way around it (mechanics and physics tell us this) but it can be reduced

Tony

( R6 CDW )

What do you do to reduce it tony?????

TonyBurns

iTrader: (3)

Twin scroll turbo is one way of reducing lag, the other is to have an anti lag system on the car but its not road legal and eats turbos
DV's dont do much though, they just get the gas out quicker (DTA) so a recirc is better in some cases....
A N/A car is the only real way around turbo lag but then you miss the kick of the turbo.....

Tony

gibbo_ireland

Not necessarily Tony, something similiar happened mine, MAF sensor was dirty due to going just slightly over the service period.

I would suggest getting that checked first, it can be cleaned but usually not successfully, replacement one around £100, but fixed the problem straight away...

nom

It's not lag. It's the MAF's underreading, so the ECU is underfueling, so the fuel mixture's not right for power... it's not really anything to do with the turbo at all! The later 'clearing up' is probably because the fueling map is more generous above 5,000rpm, which is why it's OK after that (extra fuel is normally lobbed in for cooling purposes, now there's no fuel for cooling but is right for lots of power - not good for the engine long-term!).
MY99 is likely to need a new MAF - the original design breaks, and isn't really tough enough to be cleaned (cleaning it might sort the problem temporarily, but ultimately will break it).
That should sort it out.

[Edited by nom - 9/19/2003 7:16:27 PM]

TonyBurns

iTrader: (3)

I actually never stated this was lag, i pointed out that this was a flat spot, i did give an example of what turbo lag is though

Tony

Andrewj

Many thanks guys.

Any idea how much we'll be looking at for a new MAF sensor?

TonyBurns

iTrader: (3)

MAF sensors are around 100 quid each

Tony