VS Commodore V6 rough idling, hard starting

[sheeks84]

Ive got a bit of a problem that i cant get my head around.

Cold starting in the moring, if the car is parked on a downward slope, it is very hard to start, and when it does finally fire it runs very roughly for a moment before settling into idle.
Put the car into D and the whole car starts vibrating, back into N and it gets better but not totally gone.
Once up and driving the car is very smooth, but does seem to lack a bit of punch compared to other VS i have driven.
Heres the kicker, if your at the the lights, sometimes the revs plummet and the car shudders terribly for a moment, but then goes back to idle.
And whats more weird is that the car shudders when you either turn on the AC, or press the power window buttons.

I have already done the following;
Crank angle sensor
Balancer
Leads
Engine and gearbox mounts
MAF senson
PLugs
Cleaned throttle body
Had injectors cleaned
New fuel filter

Its really starting to bug me, but im leaning towards fuel pump, what with it being hard to start on a downward angle.

Any advice would be greatly appreciated.

[justbad4you]

Ive got a bit of a problem that i cant get my head around.

Cold starting in the moring, if the car is parked on a downward slope, it is very hard to start, and when it does finally fire it runs very roughly for a moment before settling into idle.
Put the car into D and the whole car starts vibrating, back into N and it gets better but not totally gone.
Once up and driving the car is very smooth, but does seem to lack a bit of punch compared to other VS i have driven.
Heres the kicker, if your at the the lights, sometimes the revs plummet and the car shudders terribly for a moment, but then goes back to idle.
And whats more weird is that the car shudders when you either turn on the AC, or press the power window buttons.

I have already done the following;
Crank angle sensor
Balancer
Leads
Engine and gearbox mounts
MAF senson
PLugs
Cleaned throttle body
Had injectors cleaned
New fuel filter

Its really starting to bug me, but im leaning towards fuel pump, what with it being hard to start on a downward angle.

Any advice would be greatly appreciated.

have you changed coils?

[IBLOWN]

Change the DFI module & coils before you go any further. Just go to the wreckers.

[Brett_jjj]

I had a similar problem ages ago with my VSV6,every time the car sat overnight,it would misfire badly for a few seconds the first time it was started for the day,once it had been started for the day,it wouldnt happen again until it had sat overnight again.I ended up getting error code 97 setting,which is the purge cannister solenoid,so I replaced that and the misfire was gone..Id check the error codes,heres a link to a post that shows you how to do this simple test..
---Checking error codes VR/VS (Revised)---

[vs2DSIRE]

my suspcion would be a earthing problem at the battery or the earth point for the DFI take the bracket of and clean it and if that dont work have a look into the alternator

[Leevers]

Did you ever end up solving this problem? Would like to know the problem as i've got literally the EXACT same problem as yours, down to a T

[wortus]

Some of those symptoms could be a faulty fuel pump. While it's still working you might find the fuel pressure is a bit low.

[Fenix_Longbow]

I had this problem and it turned out to be a faulty fuel pump... But definitely check error codes first before you replace something else

[Leevers]

Yep, same thing, figured it out the next day, fuel pump was gone.. Quick and easy way to test it is to just turn your ignition on, and see if the fuel pump is making a noise.. If it isn't making a noise at all like it usually would, then theres your problem. Or possibly one of many problems Although only difference with your problem and mine, is that my car randomly didn't wanna start, which was because of the fuel pump..

But i still have the shutter at idle.. Spoke to a mechanic, he said it's common and more than likely that the injectors need cleaning.. But you've already done that. As my Dad suggested when i asked him what it could be, he mentioned the coils.. So i might just do the coils before anything else and see how i go

[timc83]

latley, i've found simular problems, and have worked out to be fuel pressure regulator, so that may be a chance as well. easy way to check, remove the vacumme line off regulator, and if its wet in there, its stuffed.

[daora]

Yep, same thing, figured it out the next day, fuel pump was gone.. Quick and easy way to test it is to just turn your ignition on, and see if the fuel pump is making a noise.. If it isn't making a noise at all like it usually would, then theres your problem. Or possibly one of many problems Although only difference with your problem and mine, is that my car randomly didn't wanna start, which was because of the fuel pump..

But i still have the shutter at idle.. Spoke to a mechanic, he said it's common and more than likely that the injectors need cleaning.. But you've already done that. As my Dad suggested when i asked him what it could be, he mentioned the coils.. So i might just do the coils before anything else and see how i go

mate i got mi car back from the mechanics today and yeah elminated the stalling issue they found many issues that were causing it ...Crank angle sensor
Balancer
Harmonic Balancer
dirty injectors
plugs eroded coz of e10 fuel......(when i bought mi car last thursday the guy had no idea bout cars) the car need alot of mechanical attention so i got all the major repairs done and yeah im so happy i done a major service on her too.
they even changed mi DI module too and fixed teh fuel pressor regulator