Lumpy Drive at speed in 5th

bub · 08-07-2006, 21:43

Not sure what turbo lag feels like but I have been experiencing a kind
of lumpy drive when cruising from 65 mph in fifth gear. it almost feels
like a misfire, can some explain what turbo lag is.

dstev2000 · 08-07-2006, 21:56

Turbo lag is this:

When you put your foot down it takes a little time for the turbo to spin up and send pressurised air into the engine, this is due to the fact the turbo is driven by exhaust gases. Initially you get nothing, then you get that familiar boot in the backside when the turbo is working at full capacity.

If you are in top gear and the engine is at around 1500rpm you will experience turbo lag, if you are in 3rd and the engine is running at 3000rpm you will get virtually no lag.

Turbo lag isn't jerky either.

More here: http://en.wikipedia.org/wiki/Turbo_lag

gillywibble · 08-07-2006, 22:00

You shouldn't be getting lag in 5th at 65 mph as your revs will be in the turbo range. Sounds like a fault.

bub · 08-07-2006, 22:19

Cheers lads, Thats turbo lag ruled out. and now I know what it is.
Sorry about the lack of knowledge but this is my first diesel.
P.S. The lumpy drive only seams to happen in fifth gear. Will have to
speak to stealer anyway as my cruise/c stopped working on the M8
today but has since begun to work again.

slider · 09-07-2006, 09:53

Quote:

Originally Posted by bub

Will have to
speak to stealer anyway as my cruise/c stopped working on the M8
today but has since begun to work again.

Had same problem with CC last week, haven't been to the dealer yet but the guys on here confirmed it is a known fault and is cured by a stalk replacement.

Fabia 12v · 09-07-2006, 10:08

Never had any trouble with lumpness in my PD100 in 5th... yes there is a slight lag sometimes but it depends what speed in doing in 5th... usually just pull straight away with turbo if in 5th on motorway.

yashicamat · 09-07-2006, 10:23

Generally for the 1.9TDI unit, boost builds between 1200rpm - 1800rpm, at which point you are more or less on full boost. If you cruise at 1800rpm and put your foot down, you'll get the most lag. If you're already accelerating slowly, the turbo is likely to be spinning up so the lag is reduced. As you move around the rev range, the lag reduces further still.
The key is if you are accelerating, keep it above 1800rpm if you want any sort of power. Certainly around where I live where it's very hilly, I made the mistake of changing too early when I first got my diesel. It's quite alarming when you drop off boost and loose nearly all your power on a steep hill!!

08-07-2006, 21:43	#1
bub Briskodian Join Date: Jul 2006 Location: Greenock, Scotland Posts: 99 Thanks: 0 Thanked 0 Times in 0 Posts	Lumpy Drive at speed in 5th Not sure what turbo lag feels like but I have been experiencing a kind of lumpy drive when cruising from 65 mph in fifth gear. it almost feels like a misfire, can some explain what turbo lag is.

08-07-2006, 21:56	#2
dstev2000 Briskodian Join Date: Aug 2005 Location: Back in the Green Posts: 4,022 Thanks: 48 Thanked 165 Times in 150 Posts	Re: Lumpy Drive at speed in 5th Turbo lag is this: When you put your foot down it takes a little time for the turbo to spin up and send pressurised air into the engine, this is due to the fact the turbo is driven by exhaust gases. Initially you get nothing, then you get that familiar boot in the backside when the turbo is working at full capacity. If you are in top gear and the engine is at around 1500rpm you will experience turbo lag, if you are in 3rd and the engine is running at 3000rpm you will get virtually no lag. Turbo lag isn't jerky either. More here: http://en.wikipedia.org/wiki/Turbo_lag __________________ MY08 L&K: Black-Estate-Diesel-Sunset Glass-MFD2-W8 Interior light-Colour coded door strips-LED sidelights and Puddle lights-VAG-COM fettled-Lovely! SWMBO's: MY08 vRS TDI - Standard Last edited by dstev2000; 08-07-2006 at 21:57.

08-07-2006, 22:00	#3
gillywibble Cuthbert Dibble Join Date: Apr 2006 Location: Watching Tom peeping at Lady Godiva. Posts: 7,001 Thanks: 229 Thanked 254 Times in 214 Posts	Re: Lumpy Drive at speed in 5th You shouldn't be getting lag in 5th at 65 mph as your revs will be in the turbo range. Sounds like a fault. __________________ I drink, therefore I spam.

08-07-2006, 22:19	#4
bub Briskodian Join Date: Jul 2006 Location: Greenock, Scotland Posts: 99 Thanks: 0 Thanked 0 Times in 0 Posts	Re: Lumpy Drive at speed in 5th Cheers lads, Thats turbo lag ruled out. and now I know what it is. Sorry about the lack of knowledge but this is my first diesel. P.S. The lumpy drive only seams to happen in fifth gear. Will have to speak to stealer anyway as my cruise/c stopped working on the M8 today but has since begun to work again.

09-07-2006, 10:08	#6
Fabia 12v RICHARD Join Date: Apr 2005 Location: Twickenham - Middlesex Posts: 5,030 Thanks: 11 Thanked 26 Times in 23 Posts	Re: Lumpy Drive at speed in 5th Never had any trouble with lumpness in my PD100 in 5th... yes there is a slight lag sometimes but it depends what speed in doing in 5th... usually just pull straight away with turbo if in 5th on motorway. __________________ First Car: Skoda Fabia MK1 1.2 12v Comfort Replaced with: Volkswagen Golf MK4 GT 1.9TDI Replaced with: Seat Ibiza MK4 Sport 1.9TDI Replaced with: Volkswagen Polo MK6 Ltd. Edition Sport 1.4 16v

09-07-2006, 10:23	#7
yashicamat 114whp per ton Join Date: Nov 2005 Location: Macclesfield, Cheshire Posts: 2,666 Thanks: 37 Thanked 34 Times in 31 Posts	Re: Lumpy Drive at speed in 5th Generally for the 1.9TDI unit, boost builds between 1200rpm - 1800rpm, at which point you are more or less on full boost. If you cruise at 1800rpm and put your foot down, you'll get the most lag. If you're already accelerating slowly, the turbo is likely to be spinning up so the lag is reduced. As you move around the rev range, the lag reduces further still. The key is if you are accelerating, keep it above 1800rpm if you want any sort of power. Certainly around where I live where it's very hilly, I made the mistake of changing too early when I first got my diesel. It's quite alarming when you drop off boost and loose nearly all your power on a steep hill!! __________________ Rob Nissan Primera GT in Silver '56 Octy 2 2.0TDi Elegance . . . also gone but not forgotten 2002 Fabia 1.9TDi . . . . gone but not forgotten http://uk.youtube.com/yashicamatonline

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode