wonder if anyone could shed any light...

 

the car randomly started sounded rough when I started it on Monday evening. I'd driven it earlier in the evening and it had been fine, must have been stopped for a couple of hours, then when I started it up it sounded rough. I tried starting it up again on Tuesday briefly hoping it might have gone away, but it hadn't, and I didn't have time to investigate then.

 

I guessed it was probably missing a cylinder, which I confirmed tonight by pulling the wires off each cylinder in turn. I measured the voltages on the wires from a good cylinder and compared them to the duff one, and they were the same. I then swapped the things that go onto the spark plugs (are they called coil packs?) between the duff cylinder and a good one, but that didn't make any difference. So then I took the spark plug out of the duff cylinder, but to be honest I haven't got a clue what I'm looking for there, so I took a good one out as well. Couldn't see a huge difference between the two, but swapped them round and put them back to see if the duff cylinder would swap with it... but then it started firing on all 6 cylinders again!

 

Do you think I just need to get a new set of spark plugs? (I've not changed them in the last year and a bit I've had the car). Or could it be something more serious?

Could have been just a bad connection, see what happens over the next couple of days before you start forking out on new spark plugs.

 

Paul

Has it been stood a while, mine will run on 5 for a few miles if its been left for 2 weeks or so, i guess its damp getting in the electrics, mine is a dodgy cable on a coil pack, but in daily use it does not show this symptom.

give it a good long run and that should cure it, sitting parked in this cold damp weather even if it is in a garage will sometimes cause issues

Similar symptoms to mine Phil, I didn't realise it could possibly be due to lack of use.

Thanks guys.

 

Thing is it had only been stood for about 2 hours between working fine and when it started missing, and 2 days earlier I'd been out all day in it, so it's not like it'd been stood for a long time unused.

 

I'm off in it again tonight, so will see how it goes.

Injector connection most likely, if you need a setp by step how to pm or call me at the workshop.

 

JeFf TT

The sound/feeling of a 300 engine running on 5 cylinders can be very mis-leading. My 300 sits on my drive, not covered, over winter in the elements. When i start the 'ol girl after 2-3 weeks and take her for a drive, she seems to run on 5, but..... she does not. It is simply the intake filter taking in water/moisture and affecting the maf. After driving for 30-40 mins, all is fine. This could be the issue, owing to the fact of the climate. Also, another factor could be boost/vac leak, depends on how she handles on light gas and hard gas. HTH.

 

Al.

Alan, thanks for that, although I'm pretty sure in my case it is 5 cylinders because if I unplug each coil pack in turn, 5 of them make it sound even rougher, but the 1 makes no difference.

 

Jeff, thanks for the offer, I'll send you a PM!

As with Jeff, probably a loose or corroded injector connector.

Hello Bud. Just got my Zed back after a week in surgery for exactly the same problem. Cure? Rewire to the connectors and a replacement injector (same cylinder).