z30dt Throttle snatchy/jerky

[stoph]

Slowly working my way through the problems on my recently acquired 3.0 estate..it has the potential to be a great car and at the moment just about pleases me enough to persevere a little longer! Curent 'most annoying' trait is what I can only describe as an 'oversensitive' throttle pedal, particularly when cold, extremely difficult to drive smoothly as throttle is almost on/off at times...its not my right foot I drive an octavia 130 tdi at work which is silky smooth in comparison.. with the rather 'chunky' gearchange on the vec its really irritating as car seems to throw fuel in when I lift off and you get a sudden surge which you dont want!
My first guess is going to be throttle position sensor... now is that a common problem on the vec or is it something else?? Is the sensor a separate part to the throttle body or is it a throttle body replacement? which sounds expensive... otherwise car goes well...give it a bootful and its happy even cold, its light throttle openings that are causing the issues..still doing 41mpg and starts first time when cold, sometimes second when hot...??
The words of those that know better than me would be much appreciated!

Thanks
Stoph..

[ben_3.0v6]

I'd firstly check the service history as most threads (if you do a quick search) about the v6 cdti just lately (including mine) having issue with irratic engine idle/power/speed have been due to the fuel filter. Just an idea as the filter is only around £5 from any good auto spares.

[alanv6]

You will probably find that when this surge happens, its just as you are depressing clutch, its basically when the clutch switch is activated.
Sadly you can do nothing about this as its a software issue, its when the engines had a software update in 2007 to eliminate injector phasing issues, both mine do it and all other manual Z30DTs i have driven.

[stoph]

Thanks Guys, I like Bens answer as I can potentially do something about it! Car has FVSH but its been a few miles so if filters are that cheap I'll probably throw one at it anyway..Alans answer rather winds me up(sorry Alan..nothing personal!) You are spot on in that its most noticeable just as I hit the clutch to go first to second... its a nightmare in traffic as the surge comes just before the clutch disengages... if its a software issue is it possible to update the software? I'm guessing not as you would probably have done it if that were the case! Funny that you mention manuals doing it..I'd only driven an auto signum before buying the vec and went looking for a 3.0 because it was sooo smooth in the sig... but then a 1300kg towing limit on a 3.0 auto is carp so had to find a manual and that glorious smoothness is now gone! Aaagh!!!
Chris

[alanv6]

As a Vauxhall tech ive driven lots of manual Z30s and sadly after the later software was added to them they all did this annoying jolt. Technical said that's how they will be sadly, I tried everything on my old 06 Z30, egr blank etc etc but to no avail.

[Celes]

My Y30DT does it too. I asked if they could remove the software update but said they couldn't because updates don't come on CDs anymore

[ph67]

Anyone know if the software update had an FR (Field Remedy) number for this phasing issue? My Z30DT has the same issue especially when cold - lift off the throttle and in some conditions the throttle feels like it's jolted shut and becomes quite jerky.

[Celes]

Jerky engine when you lift off the throttle could also mean worn engine mounts

[m8internet]

Mine doesn't do this (increase the revs when disengaging the clutch) such that it is noticeable during normal driving
However there is a slight "on" gas in lower gears and I got used to this after a few weeks
You need to treat the gas pedal as if there is an egg under your right foot; press gently...

[stoph]

Mine doesn't do this (increase the revs when disengaging the clutch) such that it is noticeable during normal driving
However there is a slight "on" gas in lower gears and I got used to this after a few weeks
You need to treat the gas pedal as if there is an egg under your right foot; press gently...

I can do gentle! I drive a Rapid Response Ambulance car for a living so smooth is the way to go... this is not me, its the only car I've ever had a problem being smooth with and the problem is actually worse when 'driving with an egg under your foot'... that's how I like to drive most of the time, particularly in traffic but the only way to drive the Z30 appears to be with a good quarter throttle and then I don't get the snatchiness/throttle shut off issues...its just like the throttles a bit binary at lower revs...its on or its off... many years ago I worked at Austin Rover as they were then doing some development work on cold starting on 1.6 Montegos! I told you it was a long time ago... we spent hours driving round with a laptop plugged in adjusting the fuel maps to get the driveability we wanted without killing the fuel consumption...it looks to me like Vauxhall just thought 185bhp, 400nm torque, who cares whether its driveable the figures are great!! As said in my original post I originally wanted an auto, I guess the torque converter and box will mask a lot of the problems as that would trickle around at low revs silkily smoothly... but stupid towing limit for the auto presumably due to the weakness of the gearbox...
Theres so much to like...space, comfort,performance,I even like the way it looks..I just dont know whether I can live with it!! (All I need is a nice long journey with no traffic so I'm not dawdling and I'll be fine again!!)

Chris