Help with Misfire

[StevieBoyA]

Hi

I have C180K (75,000) that has been idling unstable. Checked the engine diagnostic to reveal "misfire on # 1 & 4 cylinders". As semi-technical person I have changed the sparks plugs as first line due them being old. It has not curred the problem, I have the same errors including misfire on #3.

I am guessing its not the coils at this stage, what else could be causing the issue ???????

PS. While driving it seems to run fine with no noticable intermittant or constant misfire.

Regards, Steve.

 

[grober]

Its probably one of the HT coils. The ignition is a lost spark system where 2 plugs are fired at the same time [ only one is on the compression stroke the other is on the exhaust] 1 and 4 rise together while 2 and 3 are going down together [ one on power one on induction]. If its not the coil its one of the 2 ECU outputs.

 

[BlackC55]

What colour is your engine cover?

 

[andymerc]

airmass senor can cause multipul misfire

 

[grober]

What colour is your engine cover?

Good question Ollie I jumped to the conclusion it was a M111 not an M271 engine.