Focus Mk2 1.6i Erratic Idle & Misfire Help

[turbojoshua]

Hi There,

I have the Focus Mk2 1.6i Ti-VCT and over the past few weeks occasionally when the car is idling it will misfire or burble as I could explain and the odd backfire heard when driving/changing gear. The past few days it has been getting worse when taking the car out of gear when driving it will just die and the idle is very eratic, also noticing the brake pedal going rock solid.

There was a fault stored for "Ignition B Circuit: P0352", I have since changed the spark plugs, ht leads and coil pack to which no difference although I did notice cracks in the airbox? I have noticed when accelerating as well from 30mph+ there is no misfire or rough running, it seems to be only from low speeds or idling, car pulls fine at 70mph or what I can feel until you slow down again.

Sorry to drag on, this is really making me pull my hair out. Hopefully someone can help?

Thanks,
Josh

[Doesitdrive]

Inlet manifold, leaking pipe, coil pack, plugs and leads,

[turbojoshua]

Doesitdrive said:

Inlet manifold, leaking pipe, coil pack, plugs and leads,

Thank you for that, I have already replaced the spark plugs, HT leads and coil pack. I've got a smoke tester on order so that I can check for any leaks.

[paul_c123]

Do you know what the fuel trims are?

[Doesitdrive]

Inlet manifold, leaking pipe, coil pack, plugs and leads,

[E-bmw]

turbojoshua said:

I have the Focus Mk2 1.6i Ti-VCT and over the past few weeks occasionally when the car is idling it will misfire or burble as I could explain and the odd backfire heard when driving/changing gear. The past few days it has been getting worse when taking the car out of gear when driving it will just die and the idle is very eratic, also noticing the brake pedal going rock solid.

Brake pedal going hard means there is no vacuum in the servo indicating an inlet air leak or defective servo.

Does this happen randomly/when poor running/when starting etc?

turbojoshua said:

There was a fault stored for "Ignition B Circuit: P0352", I have since changed the spark plugs, ht leads and coil pack to which no difference although I did notice cracks in the airbox? I have noticed when accelerating as well from 30mph+ there is no misfire or rough running, it seems to be only from low speeds or idling, car pulls fine at 70mph or what I can feel until you slow down again.

It is too late now but rather than change all plugs/coils etc it would have been better to swap 2 & 1 (for instance) and see if the fault moves cylinder or not.

Putting both of the aspects of your issues above together my first post of call would be to look for inlet air leaks, could be in the area of the brake servo perhaps.

Either way a smoke test is likely to be a good place to start.

[turbojoshua]

Thank you for that, I ordered a smoke tester off Amazon last night and found a hole in the PCV valve pipe between the head area and manifold. So will get that replaced alongside the valve and re-assess. Thank you again