NGK plugs appear to make misfire worse

[mad in general]

I had a set of bosch plugs in the motor for a few months, My misfire returned last week.

I took the plunge and bought a set of the recommended NGK's as i thought id be best returning the car to standard and take it from there.

Once fitted, the misfire was much much worse and spluttering like hell whilst under load.
I swapped back to the bosch plugs and it has not missed in 3 days now.

Anyone have ideas, I dont know what was causing the mis but it appears to have gone.

Help would be appreciated, also I cannot post from my mobile for some reason so suggestions to solve the problem would be great as i wont be able to reply until tomorrow.

Also, I have plugged in a code reader and the only fault coming up was something like P1404???

Cheers

Dave

 

[aucky]

HT leads?

 

[mad in general]

I have no idea how i could test those, would those cause an intermittent fault which is now gone?

 

[DannyR]

Yes.

If HT Lead was stuck between rocker cover and plenum it will squeeze and not work. This then moves and is fine. Did it on my Missus 172, fucked the lead eventually and bought a new set for £50

 

[syko6288]

Leads or intermittent coil pack

 

[MicKPM]

Possibly a duff plug to... They do happen!