I have recently bought a 55-plate Vauxhall Signum 3.0 V6 CDTI and cannot find a workshop manual for the Z30DT engine. Do you know where I can get a manual? Haynes produce one for the facelifted Vectra C, but it does not cover my engine.
The reason I’m looking for one is that, when accelerating at motorway speeds, there is a vibration through the drivetrain. I am unsure if this is a misfire under load, as it mainly seems to happen when in sixth gear. The car is running on 19in VXR alloys with 235-35 tyres (they were on the car when I bought it), which I’ve recently had balanced to rule out any vibration from them. I realise these will be giving an incorrect speedometer reading, but I don’t think they will be causing any other issues, although I believe by using Opcom I might be able to change the setting to inform the management system of the different wheel size.
I plan to check for any engine fault codes tomorrow using Opcom. Otherwise the car is a superb drive with no other faults. Neil Roberts
Although Haynes do not produce a manual that will cover your vehicle, an electronic download covering your Signum with the Z30DT engine is available from emanualonline.
com. This is a large download and the manual is run in a virtual machine on your desktop. This will work on a Mac or PC and support is available from emanual, but it does require a certain amount of computer savvy to load the programme.
There was a field remedy (No 2439) issued on the Signum with relation to noise from the front driveshafts. The solution is to detach the front driveshafts from the hubs and grease the splines before refitting. This remedy may not be pertinent in your case, but it would be worth carrying out.
You have mentioned that the wheels have been balanced and I am assuming that this covered all four wheels. According to the data I have, the original wheels and tyres may have been one of four different sizes: 215/55 R 16-93 V, 215/50 R 17-95 W, 225/45 R 18-95 W or 225/45 R 17-94 W. Depending which tyres your Signum was configured with, the variance of speedometer reading should not be more than 2% and should not cause any problems.