Help needed please... Ve sportwagon with a stutter

Hi All

I really need some help before I end up doing something stupid like trading my vehicle or burning it!!
VE Sportwagon M6 - Mafless tune - OTR - HSV headers and mufflers - 45,000 klms on it.

About 4 months ago I noticed I was having a shudder/stutter sort of feel when accelerating. Took it to get looked at by my tuner, and as I had added an auxiliary fuel filter pre inlet manifold (to stop a fuel line harmonic noise) they pulled this and noticed it had water in it... yep copped some water in my fuel tank compliments Caltex!
Anyway it hadnt broken down as such as this filter was stopping the water entering my injectors.

So many tanks of petrol later - a few with metho and a few with Fuel Doctor we believe we have all water out of tank - BUT I still have a "stutter" (for want of a better descriptive word) going on on normal drive accelerations (you don't seem to notice it if driving hard at all).
Take it back and get the tune checked - all looks good on the laptop whilst driving... fiddle with a couple of things but nothing glaringly obvious stands out. Drive again and it is still there.
Go back and change plugs and leads... still there!!!!

To describe the problem:
I figured out tonight driving that in 2nd, 3rd, 4th or 5th when you drive thru the 2100 - 2500 rev range it gets a stutter or jumpy feel to the acceleration. If you drive along and hold it around that rev range you can feel it in whatever gear it is in. As you drive past that rev range it clears up and drives fine!

What could cause this??

Tuners next step is to set it back to standard tune and intake and see if the problem exists still... maybe the easiest at this stage - but to me if it so easy to replicate at that rev range it cant be anything to do with the water it had in the tank (?)
Maybe the injectors? But wouldnt it be more speratic instead or being in a certain rev range?

Any help would be heaps appreciated...

Have you continued checking the filter for water or just presuming the water is gone?

yep we continued for those tanks emptying it and cleaning this filter.
Then we took this filter off completely (and is still off now) to let the little bit that may have been left behind to go thru system with aid of the "Fuel Doctor" product etc.

But if it was still water, you would think it be more "hit n miss" as to when it "played up"? Not as clear as between 2100-2500rpm??

Need much more info. I quick description of how the car feels won't help much. A video of the issue ( if possible ) or a data log of the event would be better.

I'd hazard a guess that it's fuel though, if it's not still contaminated, it'll be delivery or mixtures. It's a very rough guess though.

Simon.

sounds like is load relevant. If you have a mate with same car might be an idea to swap injectors over and see if it makes a diff as injectors do not like water

Thanks for replies guys.
I think would be pretty hard to document on video as it is not a violent shake.
I am hoping it is still not fuel, Caltex have denied being responsible for the fuel contamination, even though the 7 tanks leading up to discovering the water where all from one of their servos near my home.
So it would be probably quiet expensive for me to get fuel tank out and cleaned etc.

I have just over a month left of my warranty and have had it to Holden to check. They recognised the problem, checked fuel pressure etc which is all OK. They said it is tune related and to return the car to stock tune and they would investigate further. Should I use this as my next option? Maybe they might injectors are screwed?

As much as people tend to hate Holden service, I'd agree with them that it's tune related. This is what I'd do.....

1. Reset the fuel trim data in the ECM either using a command from the tuning software or an ECM reset ( remove power ). Do this when the car is exhibiting the issue ( IE, if it's worse when the car is cold, do it then, otherwise do it when the car is hot ). Then go out and see if it feels any different. If the problem changes, then it's learnt fueling data (LTFT) and may be related to the bad fuel you had.
2. Log the car during the issue and check for any changes that are occurring in the log data. It'll take some time to separate symptom for cause, but it should be able to be done.
3. Return the car to stock and see what happens.

To be really honest, I don't think its Holden fault and I'd be pretty pleased that they are willing to look at it given the mods done. You must have a good relationship with the dealership :thumbsup:

Simon.

Thanks swing for your help
Pretty sure all fault codes have been looked at but as you say Holden have been very good at being willing to look at my vehicle even after it has been edited.
I have it booked for Tuesday to return to stock and then booked for Monday week for Holden to look for any fault ( if there still is one after tune is deleted)
I really am not mechanically minded so hopefully it is an easy fix whatever it is

what the jewl in the rough said .
If holden are willing to have a look with the tune back to stock , jump on it .

Each time I've had a stutter in the same manner as you've described, it's been because one of the spark plugs has cracked

Changed plugs n leads 2 days ago... Made no difference unfortunately.

Try the ECM reset, you might be surprised.....

I understand my car isn't the 6ltr or a VE, but i have the same problem in the same rev range as yours, only when under a medium load or half type throttle in 2, 3, 4, 5, 6 gears, when on LPG, if i run it on fuel its all good after a good run. does it feel like its missing or a hesitation and it stumbles along, till it gets out of that rev range and then goes like a rocket? I'm guessing mine is Fuel related, as pcm reset the car runs a dream on LPG and heaps of power too. after about 2 days of driving to work does it play up again. also I have a cold start issue too, with it almost stalling out (on petrol). I run the JTG liquid injection system... just havent gotten around to going back to tuner for a touch up. Guys from work have told me I blow black smoke out the back when i give it boot... so hopefully same for you.
So as Swingtan suggested give the ECM a reset ans see if it helps with the problem.

I think it is strange you felt the need for an aux fuel filter?!?

Anyway, try the ECM reset - and the logging they are talking about isn't just fault codes mate, it is the data about timing advance, knock, air:fuel ratios etc etc etc. get your tuner to do their job - I would also piss off the aux fuel filter to be honest - no need for it!

Thanks guys - how do you do a ECM reset?

The auxilliary fuel filter is off now (for the moment). It was put there as my fuel line has a really harmonic pulse noise that goes thru it that drives me insane at idle. If you lift the bonnet and grab the fuel line it stops. So the solution was some flex fuel line and a fuel filter - works a dream.
Holden were shown the problem and said there was no fix for it.

Tuner has been for 2 drives in the vehicle with me with lappy checking all - he feels it is not a tune issue.
Resetting to factory I suppose will tell the story wont it...??


Also, thanks for the helpful advise guys. Will try a reset if you can tell me how to do it properly...
PS: Just come home from driving and the car is actually worse now I have changed plugs n leads!!