Misfire, rough idle, lack of power

[Ad172UK]

Could do with a brain storm with you lot please!

Took the car for an MOT last week and it failed on emissions, fitted a new pre cat lambda and all was good on the drive home. Left the car for a few days and now it's misfiring like f**k.

Have removed the inlet assembly and Bosch plugs, checked them all and there's no obvious signs of issues, cleaned them with WD40 and a wire brush (NGK plugs are in the post) and refitted. WD40'd and cleaned the coil pack and WD40'd the leads.

Still misfiring so I pulled the leads off the coil one by one to check them. When I removed 1, 2 and 3 the car idle didn't change much but the coil arc's all over the white post so they must be sparking? When 4 is removed the car cuts out.

Checked the onboard diagnostic and there's no stored code for any injector issues.

I've confused myself and I need the car fixed by Wednesday as I'm driving it to a festival.

Don't have access to diagnostic software as I lent it out to a supposed mate who has never returned it.

 

[Dan@SJM]

Bosch plugs.

Bin them.

 

[Ad172UK]

Just the plugs? They're already half way into the bin. Would that really solve it though?

 

[Marcos999]

Mine was missing at low revs, just gave it a service including plugs and leads (from Renault), problem solved.

 

[Ad172UK]

Thinking of going for the uprated 10mm leads if I have to buy new leads to be honest.

Rather just get away with plugs though so I can finish my other car instead ☺️

 

[scotty10]

Is your leads all in good condition ?

One of mine was split and when it was raining it would get damp and misfire.

 

[Ad172UK]

You know, it does tend to do it when we've had heavy rain but in the past it's cleared up after a few days, I checked the leads but there was no obvious damage. If the plugs don't fix it I guess leads are my next call?

 

[scotty10]

do you get an orange light on dash when it happens ? that what happened to me anyway, when one lead was split.

 

[Ad172UK]

Yea, the flashing emissions light comes on, sometimes it misfires on more cylinders than others too and sometimes it won't misfire at all for a little bit

 

[scotty10]

best getting it looked at. i was lucky, i found and fixed my problem first time round.

you could end up just throwing money at it.

 

[Ad172UK]

I've had the car for 6 years and never spent money on leads, coil pack or injectors so tbh they're probably all worse for wear.

I would've hoped my injectors are fine as the car's run on VPower or Momentum all of the time.

I'll see how the plugs go tomorrow, as long as it gets me to my festival and home I'm happy

 

[Marcos999]

When i fitted a new set of leads i could feel how much tighter the new set plugged into the coil pack. I could also see some corrosion inside one of the sockets on the pack so some moisture has been getting in there.