Turbo Lag

[Fluke]

OK, I have searched, and found lots of bits and pieces on Turbo Lag, but no definitive answers.

I've had my TDI a month and Turbo Lag is the one thing I am having trouble getting uted to - outting my foot down and having to wait up to a second before anything happens.

How much lag should I be getting?
How do you cope with it or minimise it?
What might be causeing my turbo to lag more than usual?

Cheers,

 

[traumapat]

im a petrol head so this may not apply... but try getting your revs up to where the turbos working well before planting it. powers much more instant as the turbos already spinning fast.

im running a laggier turbo than you , its pretty much asleep until 3800 but then it wakes up

takes some getting used too but i think this is what makes turbod cars such a grin factor

enjoy

 

[cheshire cat]

vac leak or sticky vanes?

 

[basstard]

uh oh, nic long time no talk,,, I'll have to take my hat off,,,

Fluke, I'd get it checked since normally these tdi's aren't laggy at all: the turbines are way small compared to the engine displacement and they have variable vanes geometry,,,

 

[Sisson]

what rpm are you putting your foot down... and what gear...?

i can put my foot down in any gear any revs over 1500rpm and still get instant power...

keep it around 2k if you want no lag...

 

[BeezerDiesel]

Sounds like a pipe leaking air. Another possibility is the MAF on it's way out.
One thing to try is don't snap the accelerator pedal down, ease it down smoothly (you can still do this quite quickly).

 

[muddyboots]

We might not be talking about an actual problem here, maybe it's just that Nik isn't used to the way they drive ?

If you put your foot down at low enough RPM, it will take over a second for anything to happen.

 

[basstard]

If you put your foot down at low enough RPM, it will take over a second for anything to happen.

for one second you'll be killing the transmission then the car will start pulling,,, so something happens in that second,,,

 

[Fluke]

I do understand Turbo threshold - that below about 1800rpm the turbine is not turning fast enough for the compressor to realy contribute and so the whole thing is just an extra load on the engine. So at low revs you plant your foot and not much happens until the revs reach that threshold.

Turbo lag is different. At any engine speed, if you go from low engine load (eg foot on clutch) to high engine load (foot off clutch) it takes a finite time for the Turbo to spin up, depending on just how much time it had at low load to slow down.

Now a divert valve, or with the VNT trubos the VNT system, should minimise this lag by helping the turbo to keep spinning when the engine load is low (foot on clutch) for long enough for you to complete the gear change.

What I am finding is that, even at high revs, however fast I change gear, when I let the clutch up and flooor the gas, there is a finite delay before the power comes on. With the window open I can hear the turbo spinning down and up again during a gear change.

Maybe it is me. I have come to this from many years of driving very responsive, normaly aspirated petrol engines, so it will take a while for me to get used to a high performance turbo diesel. But my wife's turbo diesel - volvo D5, 2.4 litre, 5 cylinder, 185 PS - suffers from little turbo threshold and no discernable lag.

 

[basstard]

maybe it's just you mate,,,

or maybe you can do us a log of the turbo pressure to see what's the story like,,, it can mean nothing as well as some people might find something wrong with it,,, since we can't drive your car to test it, I think this is the best we can do to help you,,,

 

[andythom]

5 cyclinder will spool faster.....more gases to turn it....

 

[basstard]

yeah but I guess it'll have a bigger turbo as well,,, the vnt's on these cars are way undersized in order to minimize turbo lag and privilege the low down pull,,,

 

[Fluke]

Yes, I should log it with VAGCOM, but for that I will need to get my hands on VAGCOM. Just lookijng for opinions from those with experiance, so thanks very much.

I cleaned the electrical connection to the MAF sensor yesterday, and it seemed to drive much better this morning - or maybe I'm just getting used to it. I've always been and accelerator squeezer rather than a stomper. I guess I am learning to start squeezing earlier.

 

[BeezerDiesel]

The 150 TDI is well noted for lag anyway, but maybe yours does have a slight problem, worth reporting it to your friendly local dealer just in case.

 

[Fluke]

The 150 TDI is well noted for lag anyway, but maybe yours does have a slight problem, worth reporting it to your friendly local dealer just in case.

I bought it last month from Droitwich Seat, and I'm putting together a little list of warranty items for them to look at...

 

[dash]

I am not sure may be...... a green filter and bigger air intake might help with the turbo! Just a thought!

 

[Fluke]

I am not sure may be...... a green filter and bigger air intake might help with the turbo! Just a thought!

Helps any engine, in my limited experiance, but I guess it's even more beneficial in a forced induction engine.
But I think I'll wait till I've got any warranty items sorted out.

 

[cheshire cat]

uh oh, nic long time no talk,,, I'll have to take my hat off,,,

,

sorry to thread jump!! Carlo are you still on Tiscali??

 

[basstard]

 

[MDub]

The lag isn't unusual. You need to drive it differently though - as has been said keep the revs at 2k, if you plant your foot at 1500rpm naff all happens - you need to feed/squeeze the gas on to allow the turbo to build up especially when below that 2k rpm.