Engine problem - Running really rough!

[huw_jenks]

Afternoon everybody!

I've got a Y reg 1.7, only mod is the obligatory louder air filter. The car has been running faultlessly of late (as it always has done), and today I planned to drive off to see my parents, but didn't get very far. After about a mile or two I stopped at some traffic lights. When the lights went green, I tried to pull off (fairly quickly) but the car completely bogged down. I think I might have heard a 'clunk' sound too, might have imagined it. When the car pulled off the engine was seriously rough and the engine management light was flashing.

I pulled in at a petrol station about 200m down the road to investigate. The engine seemed like it wanted to stall, so I kept the revs high as I manouevered around, because I had no idea if it would start back up again if stalled. When I parked up, I opened the bonnet and investigated. There was nothing clearly amiss inside, except for the terrible noise and engine vibration. I revved the engine a little bit, and it sounded a bit more normal, but still very rough. The exhaust was popping badly, and the fumes stank.

I nursed the car home and tonight I'm borrowing a fault code reader to try and identify the problem. Can anyone suggest what I should be checking in the meantime? I've no experience of working on modern engines, my experience is with the A-series.

I've tried to upload a video which will provide the sound, but Photobucket won't let me.

Huw

 

[red]

Hi huw, could it by spark/coil related? Maybe it wasn't firing properly

Could start by inspecting the spark plugs.

 

[tuonokid]

Hi Huw
Has the engine been making a slight tinny rattle on idle lately? That's the sign of a worn cam belt tensioner and it sounds to me like it's possibly let go and the cambelt may have jumped a couple of teeth. I wouldn't drive it anymore until you can check the engine timing. I hope it's not that but it's worth checking.
Barry

 

[Waterboard]

I bet that’s an air hose discon’d off the manifold. Check around the throttle body and manifold. Bet it’s an easy fix..
Good luck

 

[huw_jenks]

Right, I've run a DTC scan and it's come up with the fault code P0304 (cylinder 4 misfire). I've got tight seals on all the hoses, should I replace the coil and spark plugs next? Spark plugs have been on my list to do for a while tbh.

 

[Wild E. Coyote]

If coilpack hasn't been replaced, I'd turn my attention there. Try to borrow a known good one and then see what happens. Also, the spark cable might be worn and bridging to engine.
Also, maybe your cam cover gasket is leaking (a known problem) and the 4th cylinder spark might be in oil bath and that is causing misfire.
If it is a consolation, none of these is a biggie to sort!

 

[huw_jenks]

I replaced the coil pack, and she started running properly! I decided to replace the HT leads and the plugs at the same time, and she is positively purring. There is quite a bit of oil swilling around in the plug holes, so rocker cover gasket is next job on my list (of many, many jobs).

Thanks for the advice everyone!

 

[N1X]

That sounds a result !!

 

[red]

excellent, thanks for reporting back.