Random misfires on startup

J

JohnMRZ4

Member
Hi all, hoping you can help me diagnose a problem.
I started my z4 and it was running very roughly, I got P0300 and a warning light. The engine was physically shaking, so I took a look for anything obvious and found a hole in one of the hoses that runs from the air filter where the hose has perished over time. Looking from the front of the car to the rear, it's the hose that does goes left into the engine from the air filter housing. I decided not to drive it incase there's damage caused to the engine but I need to drive it to the garage for a fix and it's 40 miles away from where my car is at work. If there is a vacuum leak will it cause any damage? Has anyone else had this crop up?
 
Put some tape over the hole to start with and try again? P0300 isn't specific just a misfire code, maybe INPA will give a better code. I assume it was a generic code reader?
 
ph001 said:
You need a garage to change a hose?
Click to expand...

Why is that so strange :? i would too :? but i could install a truss roof , construct a decent extension from scratch , screed & lay a karndean floor , convert a French barn etc all quite easily :wink: not everyone chooses to work on their own cars , i never have , perhaps i could but i don't .
 
Scooba_Steve said:
Put some tape over the hole to start with and try again? P0300 isn't specific just a misfire code, maybe INPA will give a better code. I assume it was a generic code reader?
Click to expand...

It was a standard reader, I will get some tape and give it a go and see if it fixes it. The hose itself is quite tricky for a newbie like me to get to and change myself :?
 
Well, I taped up the hole but it didn't fix it. So I'm lost as to what it might be. I took a video of the engine featuring the noise it's making. Any ideas what it sounds like? The unusual sound is like a steam train - the chug chug chug

https://youtu.be/vDSYOSWPjWM
 
I suppose my first question is, does she run ok after a few seconds or is she running rough all the while?
Sounds very much as if she's 'inhaling' far more air than she normally should?
I would take the air filter out, remove the air filter box & make sure all the hoses etc seem ok & go from there.
I know when I bought mine [3.0] carried out a full service then blow me, the yellow engine light came on, turned out to be the air filter box 'elbow' pipe had deteriorated badly.
Carry out the simple bits first then see where you are.
Just a thought........it wouldn't be something as stupid as a loose spark plug?

Tell us how you get on.
 
I have run the engine for a good minute or two and it keeps going as-is in the video with no signs of letting up.

Looking at the hoses I taped-up the bit where I could see an obvious rip, I didn't see any other splits.

The strange thing is it drove to work fine, then I came to go home and this started.

I guess other causes maybe valve cover gasket ? Bad coil packs probably wouldn't cause this sound?
 
A bad coil pack/spark plug would cause a misfire and would first show itself under load. This doesn't sound ignition related.
 
Weirdly it was the coil pack on cylinder 2, replaced it and it is now running well, I didn't think it would be that simple. Thanks for all your help and replies
 
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