Engine misfiring at low RPM...
So my engine has a weird problem where it misfires but only upto about 1600rpm. I’ve changed the plugs recently but it still happens. Where do I go next? HT leads?
So my engine has a weird problem where it misfires but only upto about 1600rpm. I’ve changed the plugs recently but it still happens. Where do I go next? HT leads?
Comments
How old is the car? If it still runs on a distributor system it sounds like it could be a vacuum advance problem.
None of the mk1 Focuses have distributors so it’s not that.
Most likely a coil pack issue, that would be my next choice, really common and cheap to fix too. Just dont mix the leads up when you’re swapping them over.
Yeah I’ve seen and heard what happens… Luckily the OEM coil packs for the Focus are numbered.
Well if you can afford genuine then i would go for that but one of the better quality ones from someone like euro car parts will be absolutely fine.
You sure its a misfire and not an air leak? Aka pirate air?
Mine had a similar issue, check the Vacuum hose behind the inlet manifold (if it’s a 1600 petrol)! The heat and suction causes the pipe to collapse over time, and sometimes with quick bursts of high throttle the pipe can close up briefly and cause a missfire.
I had the same on my 1600, and it eventually collapsed completely and only ran on 3 cylinders! Check this first as it is a visual inspection rather than buying and trying!
I never thought to check that, I’ll have a look later. Although wouldn’t that also cause it to have an erratic idle aswell?
And mine’s a 1.8 petrol but I really wouldn’t be surprised to find it acts the same, as they all seem to share a lot of components.
It can do, sometimes it doesn’t take effect on the idle speed, sometimes it can make it stall when the clutch is dipped!
Not sure where exactly the breather hose is in the 1.8 though… Had a quick look at replacements and it doesn’t look the same! I guess just look out for collapsed pipes connected to the engine headers or block.
The breather hose is on the inlet side (the back as you look at it) of the engine on the 1.8 and 2.0, and thinking about it, I think that’s pretty knackered.
If it misfires on low rpm it’s probably something with fuel delivery to the combustion chamber or with it’s lighting - so check injectors and spark plugs (cords included)