help

Hi just put my car on nostics machine to see if there are any problems as my uncles just bought one and its showing up, random cylnder misfire?? what does this mean and how do I fix it, is it anything to worry about?

Probably one of the coil packs is playing up. Have you ever replaced any/all of them? Do you know when they were last replaced? One of mine has been cracked for some time (2+ years!) and I'm just waiting for it to give up before I replace all six. It might be a misfire that you were unable to detect yourself - but it was enough to put a record on your computer. Not sure if you already know this but the coil packs (six, one on top of each spark plug) are prone to cracking and general abuse because of where they are located - very near the ground. So they regularly get very hot (from the engine) and very cold and wet and covered in cr*p from the road. If she's running smoothly and you haven't got your "!Check engine" message on your OBC then I would be inclined to leave them alone until you either get this message or you can feel her running a bit lumpy. To replace the whole lot will set you back around £250 to £300 - from Euro Parts or somewhere similar. Having said all of the above it could also have just been a bit of dodgy fuel at some point that set it off..? Hope this helps. Adrian. Sorry: Just to clarify, having a dodgy coil pack has the same effect on your Porsche engine as quickly removing and then replacing one of the HT leads on any other engine: she'll quickly misfire on the cylinder that you've removed the HT lead from and then come back in to timing when you replace it.

oh right, thanks for that mate, today i ran the car on very low fuel and just made it to the garage. wonder if that could have did it. The car feels fine and the management light is off. The light was on before christmas but it just went back off and I thought it was down to cold weather on battery, I think i would wait untill the light comes on and replace them all at the same time. hey and thanks.

Yeah. Running her low (how low?) on fuel is a bit of a no-no and might well have caused your message. If she's running well otherwise I wouldn't worry yourself about it. The engine management system is sure to let you know if there's a problem - and sometimes when there isn't![ ]

you know the bottom line then you get to the big block, well I had to run it just under the line, I hated doing it but I misjudged the garage

Ok. If she's now running ok then I'm sure that you're fine.

yer shes running good, how would I notice misfire, what would happen?

The cylinders are horizontally opposed to each other - so any uneven running is going to produce some uneven side-to-side effect on the body of the engine which will then transfer to the car itself. It might feel like the back of the car is wiggling from side to side when she's idling and you might notice a slight temporary drop in power if she misfires under power. There are probably lots of other symptoms that could occur: a darker than usual exhaust smoke from one of the exhausts or even a back-fire. Your exhausts don't correlate to the two banks of cylinders: the left one deals with the exhaust fumes from the right bank of cylinders - and vice versa. When you have the chance have a look under the back of the rear bumper - you see that the exhausts cross over behind it.

ahhh, ok great thanks for the info mate. I will check it out when its daylight and thanks again.

I presume you got fault code P0300 - Misfire Detection - which would be accompanied by other P030x codes (where x is the cylinder number). If the car is running fine, I would suggest noting the code(s) and clearing them. Give it a run, and check the codes again. If the same one(s) comes back, then you can be fairly confident which coil packs need changing. If, however, you were getting codes for all cylinders on one bank, then it might not be a coil pack, but may be a Variocam solenoid problem. This would most likely cause a lumpy idle, and loss of performance though.