I've spent the last week or so trawling the wealth of info on this great forum, but I'm still left a bit puzzled with my problem - I'm hoping I can get some suggestions here which are better than my local garage's idea for next steps!
A few weeks back I started getting misfires when starting from cold, which seemed to be cured by driving for a few minutes, switching off for 30 seconds and then it would run smooth as ever. First time it happened I drove straight to the garage, and apparently the tech2 was reporting a misfire in cylinder 1 but nothing else (no sensor error codes).
They advised to keep driving and see if it gets worse, and to go back in a few days if it did.
I added some injector cleaner to the existing half tank of petrol and topped up.
After a few days, it started to feel more sluggish so I booked it in. Garage did compression test, all fine and determined it was either the coil pack or sticking valves - advised to replace coil pack and plugs @£250 and see how it goes, so thats what I chose.
On picking up the car, the idle was still a bit rough at times but wasn't making the car rock like it was. Got them to check it before I left, and they agreed it was a bit bumpy but charactaristic of this engine. Agreed to drive away and see how it goes, so I went to put my foot down around a few places.
All seemed ok for 10 minutes until the emissions light came on and starting flashing every time I touched the accelerator. I pulled over, switched off for 30 seconds, started up and all was fine again. Called garage, they said that the diagnosis was still the same and therefore can either leave it a few more days and see what happens or the only other route is for them to strip the head down to de-carbonise it (mega bucks!!).
Next I decided to run down the current tank of Fuel by driving up and down the motorway until the light was flashing, and filled up with BP ultimate. Still not much change until Friday, when I was heading for a 100 mile or so trip, and it started misfiring towards the start of the journey, again emissions light flashing. I pulled over as soon as I could, switched off and on again - all fine and smooth again. Since Friday, it hasn't got that bad again.
Didn't use car saturday, on sunday drove about 50 miles - smooth as ever. Then as planned (needing assitance ) poured 1/4 bottle of redex into the the throttle body with the engine revving, and cleaned the throttle body with carb cleaner as in the provided here!
Drove another 150 miles home, with a quieter sounding engine - but still a little rough at idle when at 900rpm. Because the fault codes were still stored I couldn't tell if there was still a problem as far as the car was concerned, so today got the garage to clear the fault codes for me.
After about another 20 miles of driving the light came back on, so within 5 mins I pulled over to do the pedal test and get the codes.
Its now reporting the same batch of codes again, yet this time I didn't even feel the engine mis-fire, its been smooth other than the rough idle since Friday!
So, it can't be the coil pack or spark plugs - unless both the old and brand new ones are all faulty...0300
0314 (misfire when low on fuel? haven't been low on fuel since the codes got cleared)
What else could it be? Anything else I can look out for to give a clue?
I don't fancy spending £800ish to get the head stripped, and thats pretty much the only option I'm given at the moment by the garage and I'm not convinced it will do anything!
Thanks for reading.... looking forward to your input on this challenge!