Turbo Diesel power band

Olly H · 12-12-2006, 12:39 PM

My girlfriend has a Mk4 Golf GTI Diesel (I think it's a GTTDI or something) it's 130bhp standard and has "apparently" been chipped to 150bhp by the previous owner. (who she knew and was fairly trustworthy)

Anyway, I've driven it a couple of times, but I've never really liked the power delivery. It pulls well when the turbo kicks in at about 1800rpm but it seems to dramatically tail off at about 2200-2300rpm.

I've not driven too many turbo diesels, but the fading power when overtaking can be quite disconcerting.

1 - Is that just how they are? ...or is there something up with this one.

2 - Who's got one? ...and when do you change gear if you're "nailing it"?

3 - Anybody got a torque/power curve?

tej · 12-12-2006, 12:42 PM

our mondeo kicks in just under 3k and all hell breaks loose till the red line really.. you pretty much run out of revs.. its quite laggy below 2.5k

ChrisC · 12-12-2006, 12:44 PM

My mondeo kicks in at 2200rpm and as Tej said, it accelerates hard until 4000rpm, it runs out of acceleration at 4500 and when you get into the red it does diddly squat.

Mine unlike tej's isnt that laggy BUT i do rev it hard to get it to 2200rpm

Dr.Jones · 12-12-2006, 12:49 PM

Mine did the same when the MAF sensor had gone.
Replaced it and it pulls all the way to 4500 ish now.

So I'd say:

1.Yes something wrong
2.Change gear at 4500 when nailing it
3.No

chiark · 12-12-2006, 12:51 PM

I found the old golf a lot like you describe - big hit at around 1800rpm, then tailing off over 2500.

Chipping does seem to open up the top end in general. I know mine (330d) now "pulls like a train"* until about 4,800 from 1,600... Before it ran out of legs at around 4k.

* - every diesel owner must use this phrase at least once a day otherwise they get their smoke machine confiscated. It's the law.

tej · 12-12-2006, 12:52 PM

Chris, yours is chipped right?

sounds like your power band has been shifted to lower down in the range.. ours pulls pretty hard to the red line as keeps going into the limiter zone...

ChrisC · 12-12-2006, 01:01 PM

Quote:

Originally Posted by tej

Chris, yours is chipped right?

sounds like your power band has been shifted to lower down in the range.. ours pulls pretty hard to the red line as keeps going into the limiter zone...

nope.. just driven back to work, just had a quick play

pulls from 2200rpm when the turbo feels likes its kicking in all the way to 4200rpm ish, it still accelerates to 4500rpm but its less obvious.

When i was ragging it in 4th the other day it was doing ~105 @ 4500rpm, the 100-105 was considerably slower than the up to 100.

Blade · 12-12-2006, 01:03 PM

Before the remap power came in at a little over 2K rpm with power tailing off at about 3.5K rpm

With the remap power kicks in at 1.8K rpm and gets best results revving up to 4-4.5K rpm.

tej · 12-12-2006, 01:05 PM

Quote:

Originally Posted by ChrisC

nope.. just driven back to work, just had a quick play

pulls from 2200rpm when the turbo feels likes its kicking in all the way to 4200rpm ish, it still accelerates to 4500rpm but its less obvious.

When i was ragging it in 4th the other day it was doing ~105 @ 4500rpm, the 100-105 was considerably slower than the up to 100.

i will have to have another play.. i was in the mondy yesterday, as soon as i put my foot down for a little "experimentation" a copper blew straight past me going the other way, so i eased off

but im sure it pulls hard past 4.5k

ChrisC · 12-12-2006, 01:09 PM

it wont pull hard past 4500rpm.. thats the redline. it stops at 5000rpm and the engine cuts out (i know)

RickyLee53 · 12-12-2006, 01:09 PM

Quote:

Originally Posted by Olly H

My girlfriend has a Mk4 Golf GTI Diesel (I think it's a GTTDI or something) it's 130bhp standard and has "apparently" been chipped to 150bhp by the previous owner. (who she knew and was fairly trustworthy)

Anyway, I've driven it a couple of times, but I've never really liked the power delivery. It pulls well when the turbo kicks in at about 1800rpm but it seems to dramatically tail off at about 2200-2300rpm.

I've not driven too many turbo diesels, but the fading power when overtaking can be quite disconcerting.

1 - Is that just how they are? ...or is there something up with this one.

2 - Who's got one? ...and when do you change gear if you're "nailing it"?

3 - Anybody got a torque/power curve?

It is possibly overboosting before then and dropping back to normal boost afterwards. Does it tend to drop off earlier in higher gears?

Dr.Jones · 12-12-2006, 01:10 PM

power in any Golf TDI should not be lasting for only 500 RPM.

Something is wrong. Sure power delivery is short, but not that short

should come in anywhere between 1700 and 2000RPM and last a good couple of thousand RPM before fading out. Tailing off before 4000 RPM is a sign of a faulty MAF IMO.

Benny · 12-12-2006, 01:15 PM

Quote:

Originally Posted by chiark

* - every diesel owner must use this phrase at least once a day otherwise they get their smoke machine confiscated. It's the law.

Baaahahahahahahaaaaaaaa!

B

ChrisC · 12-12-2006, 01:18 PM

i suppose pulling like a train is right in some cases... lots of acceleration and cant go round corners quickly

Dr.Jones · 12-12-2006, 01:19 PM

whys it good when cars handle like they're on rails then

ChrisC · 12-12-2006, 01:21 PM

i've never understood that comment. i think they mean that its sure footed.

Baz W · 12-12-2006, 01:29 PM

Quote:

Originally Posted by Blade

Before the remap power came in at a little over 2K rpm with power tailing off at about 3.5K rpm

With the remap power kicks in at 1.8K rpm and gets best results revving up to 4-4.5K rpm.

thats pretty much the same as my car before and after.

the revs build a lot faster now which nice

tej · 12-12-2006, 01:29 PM

Quote:

Originally Posted by ChrisC

it wont pull hard past 4500rpm.. thats the redline. it stops at 5000rpm and the engine cuts out (i know)

is the redline at 4k or 5k?

basically it pulls hard up until the limiter

ChrisC · 12-12-2006, 01:33 PM

redline starts at 4500, limiter is 5000

mine doesnt accelerate much through the redline area

tej · 12-12-2006, 01:35 PM

Quote:

Originally Posted by ChrisC

redline starts at 4500, limiter is 5000

mine doesnt accelerate much through the redline area

the differences are strange given that they are the same engine

ChrisC · 12-12-2006, 01:41 PM

saying that, i dont like driving it in the red.

I'll go for a drive tonight

and find out

Keviño · 12-12-2006, 02:06 PM

1: its broken, i agree with the doc, try a new MAF

2: 4500-4800 rpm

3:

edit: i realise thats plotted against speed, but they were the only graphs to hand.
ill go and re-output some when jeff's finished useing the rolling road.
luckily, i also have a graph with my leon PD130 with a fúcked MAF

Olly H · 12-12-2006, 02:09 PM

Sounds like there's something up then!

So the best bet by the sounds of it would be to drop it into a garage, tell them the problem and ask them to check the MAF sensor. I remember the air flow meter on my 205 gti playing up, that caused all sorts of havoc, it was a mechanical flappy one and was easily sorted with a bit of carb cleaner. However I suspect this is a "hot wire" system or whatever they use, with no moving parts.

I was worried that it had been incorrectly chipped and that was causing the problem. Although I guess I still can't discount that option.

Will the garage just plug it in and run a diagnostic to check the MAF sensor?

Matt_82 · 12-12-2006, 02:17 PM

i had a tweaked 130pd audi a4. that picked up at 1400rpm and wanted to go past the red line

should pull hard right past 3k

Keviño · 12-12-2006, 02:19 PM

if you're going to take it to a VW garage, theyre gonna charge you at least £70 diagnostics fee to take maf readings.

do you know anyone with vag com?