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Help *was* needed after spark plug change

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I'm getting a coil c CEL, which I infer implies the coil pack is not correctly seated in place. The car ran fine on its first journey but I'm pretty sure it's firing on three on second start. Very uneven idle.

Q1: which one is coil C? The Americans say passenger side rear, which might be drivers side over here..

Q2: during the change we're not sure we used the right bolts for the right things. There are short 10mm ones, and longer 10mm ones with a tapered nose. Which ones hold the coil packs, and which ones hold the injector ECU to the side of the engine?

It was a nasty and slow job, so I'm not pleased to have to go back down there! Hope you can help me clarify this!


I have also noted that the HKS plugs supplied by Fensport have only one prominence compared with three on the Denso plugs that came with the car. I don't believe that will be an issue, but it's interesting.

Edited by nerdstrike

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Tapered bolts are for the injector ecu, standard bolts for coils, one short bolt for the fuel rail cover.

One of my coil pack cables wasn't quite clicked in it seems, as when I tweaked it, it clicked. Cleared the code on the ecu and the car got back into the mood. Coil C is rear most on the UK driver's side.

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Here is a brain dump of all I have learned while trying to do this:

Firstly, the process takes ages. Unless you have magic tools, it will be incredibly slow, like an hour a plug or more as you get tired or drop things

3/8" kit is well suited. 1/2" ratchets are too large. 1/4" helps for the coil pack bolt and other ancillaries that must be removed. Vortex/through sockets are your friends here too as they increase your options. They might let you get a longer handle on a small job, you're going to want that!

A flexible magnet on a stick is absolutely indispensable. Ideally not too magnetic to help with threading the needle. You *will* drop something eventually. Otherwise you need to get the car up on stands so you can poke around the drainage holes or take the undertray off! Otherwise small bits of cloth it towel can be jammed underneath, but I couldn't get full coverage.

There is a tonne of thread on the spark plugs so the combo of socket and extension that works initially can be too long to get out once the plug is loose! Nicely worn extensions will be easier to detach than new ones, and a long flat bladed screwdriver might help depending on your stuff. My halfords advanced 3/8" short extension was too long to separate with screwdriver so I had to man up to detach it from the socket with fingertips of one hand.

Each spark plug requires slightly different tricks! Driver's side is most accessible and the passenger side is always difficult unless you care to mess with fuel lines or aircon. Taking the battery out gives you more elbow room to come in under the hardlines. I've used a mixture of the following tools while trying to find the easiest method:

1/2" ratchet + 3/8" adaptor plus very short extension in to deep 15mm socket. Then remove the insert to get it all the way out before you run out of length to remove anything. Stabilise the turning with a finger to make the ratchet click

3/8" ratchet + short wobble bar plus deep 15mm socket. Crack it loose with the ratchet, then twiddle with fingers. From certain angles it is possible to grip the extension with thumb AND finger! What a treat.

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