My VE has problem please help

[ROBBO13]

Hi Guys, I have a problem which has just appeared today. I plan on heading to the dealership but hoped for some insights from some of your first. I have a 2006 VE SS A6 with CAI and 2.5 inch X-Force exhaust and Headers. It has no tune as such because I didnt want to push the warranty scenario too far. I believe it has had something tweaked so that the o2 sensors dont kick up a fuss from the exhaust change. The car has been fantastic with however this afternoon I noticed an odd shudder that I only notice when at and above 100km and particularly when under acceleration, most noticeable under light acceleration from 100km up.

This is weird as the car was great on Wednesday when I drove to Phillip Island and back, plenty of overtaking (a breeze in the SS, and a big smile on the dial) and no sign of any shudder. Even this morning I noticed no problem. BUT, this arvo when I drove home I noticed the problem and further investigated the issue tonight with a run down the freeway.

Note: The problem is no better or worse when in tiptronic or standard auto. When free reving the car in neutral there is also no sign of problem. It would seem to be an issue only occuring under load and most noticable at and above 100kmh.

My next guess was that I had bad fuel...but...pre driving to Phillip Island on Wednesday I filled my tank from about quarter of a tank to full with Mobil 8000 98 RON fuel (as I always do) and made the 200km or so round trip with no issue. I now have about about quarter of a tank or so left of that same fuel so surely that cant be the problem? Can it?

No doubt many of you are mechanically capable so I would really appreciate your thoughts. Of course I plan to go to the dealership but am nervous about their reaction and whether they will claim the exhaust is the problem or something. It is my first new car so I am a little stressed :)

Car has dont 27,000km so is just shy of its 30,000km service.

Hopefully it is a simple fix?
Appreciate any thoughts, thanks.

[Titanium]

Thrown a wheel weight .... just a thought.

[cholo]

I dont think it has anything to do with the exhaust which Im sure the dealer wont see it being the cause.

Maybe its a gear problem?

cheers

cholo

[planetdavo]

Torque convertor doing it's locking/unlocking function?

[CalaisRider]

Torque convertor doing it's locking/unlocking function?

Yeh I had the same issue when a run in tune was put in the VE after the cam and other engine mods were done. All gone now with the complete tune done.

The key bit is that I had a bung spark plug and a almost stuffed coil pack. These were replaced whilst tuning for the cam. Mine is a 2006 model as well...

I have no idea what actually causes it but I know mine was at a stage where you could see the dash actually vibrate under full load. It didn't happen when I was down a gear or two with a few revs under it. All good now though.

I'm no techo guru but would suggest its Plugs, coil pack or tune.

Pete

[ROBBO13]

Thanks for the responses so far guys. I booked my car in for the 3/1 to get it looked at and have its 30K service. The dealer guy I spoke to today said he thought it sounded like the torque converter locking in but I'm not so sure as this is certainly a new problem and he was implying that this shudder may have always been there at that speed which is certainly not true.

The spark plug, coil pack tune scenario sounds feasible but if this were the problem would I not expect the car to be rough when free revving in neutral? When I rev the car in neutral all seems fine. I would have presumed plugs and coil packs would not be effected by the car being under load.

That leaves the tune........ which I'm sure with the changes I have made would be great for the car but I have been driving around for nearly 2 months with the current setup with no probs.

Hmmm, It would be great to head into the dealership having a good idea myself what may be wrong. Thanks for the suggestions so far.

Cheers,
Chris

[Curtis-R]

Ive also heard of bolts in the tailshaft bending or warping which can cause this, but I imagine you woudl have to get a lot of axle tramp etc for it to do this. One of the symptoms was the sort of vibration you mentioned. Excessv had this problem, so that's how I know.

Good luck with it.

[ROBBO13]

In my quest for an answer I just rang a holden service centre in Sydney even though I am Melbourne based as they had been given great praise in another forum. The service guy I spoke to suggested it could be a vaccum hose which has some credibility as the drive the other day was the first time I have given the car a hard drive on a warm day since getting headers etc which possibly heated and damged the vaccum hose?

I used to have a VP Commodore and the vacuum hose completely dislodged on that one night and it ran as rough as you can believe and I thought the motor was totally castus until the RACV guy came along, plugged it back in and she was good as new! So if if it is just a damged vaccum hose that could could explain my problems. This service guy in Sydney says he had this issue on another car the other day.

Anyway, there is another potential explanation for the list. Maybe this info will help someone else at some point.

I am a stresser about these things :) I dont want to have a warranty argument with my dealer and have him point fingers at the exhaust change.

For Sydney people I rang 02 9357 4272 137-157 Bourke St
They were very helpful considering the time of year and they had no chance of getting business from a guy in Melbourne.
Chris

[ROBBO13]

Thanks for the contributions guys, got my car back from its dealership yesterday after getting them to fix the problem and complete its 30K service.
Turns out it was a broken tailshaft bolt! Oops. I havent heard of that happening before. Also I am going to start another thread asking about O2 sensors as they werent able to update my Body Control Module Software for some reason. They believe it may be because of a tweak by the guys that did my exhaust. I rang the guys who did the exhaust and they said they have simply added some code I presume which disables the diagnostic test the car runs on the O2 sensors. I will need to get this removed and then go back to Holden for the software update. I know most people solve the problem when they get the car tuned which I have resisted for fear of voiding my warranty. Is there a better solution? Should the O2 sensors be repositioned so as not to trigger an alaram?

Chris

[Curtis-R]

Thanks for the contributions guys, got my car back from its dealership yesterday after getting them to fix the problem and complete its 30K service.
Turns out it was a broken tailshaft bolt! Oops. I havent heard of that happening before. Also I am going to start another thread asking about O2 sensors as they werent able to update my Body Control Module Software for some reason. They believe it may be because of a tweak by the guys that did my exhaust. I rang the guys who did the exhaust and they said they have simply added some code I presume which disables the diagnostic test the car runs on the O2 sensors. I will need to get this removed and then go back to Holden for the software update. I know most people solve the problem when they get the car tuned which I have resisted for fear of voiding my warranty. Is there a better solution? Should the O2 sensors be repositioned so as not to trigger an alaram?

Chris

Hey Chris as per my post (reply) my guess was right. glad you got it sorted. just take your car to a forum sponsor and they should be able to quickly remove that fault code. It does require a tune to do this. chevs autos in Carrum could do this for you. I had the same problem when fitting the exahust and it was fixed very quckly. Have you had the car run on the dyno since fitting your mods? might be worthwhile to ensure all your AFRs are good and the engine is running smoothly.

Cheers
Curt.