Misfiring

[MAMOOK]

Hi All,

Hope you and your Beats are well.
26912692
My car has developed a misfire when started from cold. I haven't driven it for any length of time since this fault has developed so I don't know if it will disappear once warm. I've decided to remove and replace the capacitors in the ECU as part of my fault finding mission.

Pictured is my ECU. All the caps look in good condition and there are no signs of corrosion but I'm going to swap the vulnerable ones whilst I have access to them. Some of the caps look to have been marked, do we think that they have been replaced already or was this factory standard?

If this doesn't cure the problem what next people?

Major service done approx 3 years ago. Oil is in great condition. Done approx 5k in those three years.

[stu g]

Hi Mamook,
Have you tried looking at the basics? A misfire is most likely caused by the spark plugs not firing correctly. I'd first have a look at the ignition system.
Start with the distributor cap - take it off and ensure it is clean inside - have a look for any characteristic electrical tracking - make sure it is fitted correctly.
Check to see that the rotor arm is not pitted.
Then look to see that the HT leads are clean and fitted properly at both ends - if they are not seated properly you'll get problems. Moisture can build up on the leads and cap and this can result in shorting.
Check your spark plugs - check the colour and gap. If you are that worried (and because plugs are cheap) just replace them.

Stu

[Strangerover]

I would check all timing marks align as well as above...

Also check the ignition timing....

When you say misfire.... could also be air leak or fuel problem if old fuel ??

[Seventynine]

as everyone else has said. 3 years is well outside of the service interval of any car regardless of mileage! i'd start at the basics, new plugs and fuel, then go through the ignition system

[MAMOOK]

Hi All,
Just remembered I had the oil and filter changed at MOT time last year, no wonder the oil was so clean!!!
Swapped the plugs for new ones tonight. Removed and cleaned the Dizzy cap which was nice clean and dry already to be fair. Cleaned all leads. Problem still exists.
I will check the rotor arm next. Forgot this evening.
Caps have arrived so I will swap them out when I get time.
Fuel is very fresh.