Vauxhall Meriva - Cylinder 4 misfire detected

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Wed 10 Jul 2024 16:58
Vauxhall Meriva - Cylinder 4 misfire detected - rustonboy

My engine has suddenly started running lumpy at tickover (particularly noticeable at about 1000 rpm). At higher revs the engine is obviously not happy either, and the car feels underpowered. The engine is petrol 1.6 litres DOHC (engine type Z16XEP). My little OBD reader says error P0304 Cylinder 4 Misfire Detected. I think cylinder 4 is the one f***hest from the timing belt end. I had a look at the spark plugs, and they seem fine, though the one in cyliinder 4 looked very slightly sooty. When I put it them and the ignition module back, there was no improvement and the same error showed on the OBD reader. Might this be something simple, or am I in for a nasty shock at the garage? Please offer advice if you can - many thanks :-)

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Wed 10 Jul 2024 17:09
Vauxhall Meriva - Cylinder 4 misfire detected - elekie&a/c doctor
Very common for the coil pack/ cassette to give problems. I would also check the connector to this as this can cause issues.
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Wed 10 Jul 2024 18:44
Vauxhall Meriva - Cylinder 4 misfire detected - rustonboy

Thank you so much, doctor - your input was spot on! It seemed there was no way of knowing without trying, so I trusted in fate and found that eurocarparts was still open until 6, so I bought the part and came home and fitted it and yippee - the engine is running fine again. Not the cheapest fix (£80), but so much cheaper than a garage. Can't thank you enough - v. grateful for your help over the years :-)

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Wed 10 Jul 2024 17:26
Vauxhall Meriva - Cylinder 4 misfire detected - edlithgow

If these are a coil-on-plug type (which of course I've never had), I'd think you could swap bits around and see if your misfire moves to another cylinder, and so identify the faulty component,.

I'm assuming they arent coded to the individual cylinders or some such ludicrous new car c***.

That'd be ridiculous, of course, but that doesn't seem to be any sort of guarantee that they wouldn't do it

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Wed 10 Jul 2024 18:51
Vauxhall Meriva - Cylinder 4 misfire detected - rustonboy

Hey - thanks for your suggestion. The ignition coil module is a single integrated unit with one in-line coil per plug, so unfortunately your otherwise sound idea of swapping things around would not work on this occasion. I know what you mean about new car c*** (mine is a 2006 model), but I remind myself how hard (and dangerous) it was to start unwilling cars with a crank handle in the olden days :-)

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Fri 12 Jul 2024 03:07
Vauxhall Meriva - Cylinder 4 misfire detected - edlithgow

Well, AFAICT without knowing the car, it would still have allowed you to provisionally eliminate plug and lead faults before you shelled out 80 quid for the unit, but anyway it worked out ok

I started my MkI Lada a few times using the starting handle, perhaps the last starting handle available on a new car ( the enormous OEM battery was finally dying), and it just worked. Mostly it was just useful for turning the engine for doing the tappets, manual timing chain tensioner and such.

They'd taken it out on the Mk 2 I had briefly. The lugs were still on the end of the crankshaft but there was no port in the radiator so you couldn't reach them. I THINK it had a rubber timing BELT as well!

Western Decadence.

Edited by edlithgow on 12/07/2024 at 03:10

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Wed 10 Jul 2024 18:54
Vauxhall Meriva - Cylinder 4 misfire detected - elekie&a/c doctor
May be an idea to replace the spark plugs also . It’s possible for corrosion to build up at the top connector tip and cause a poor contact into the coil pack
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Thu 11 Jul 2024 11:34
Vauxhall Meriva - Cylinder 4 misfire detected - rustonboy

Will do - many thanks for the tip!

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Thu 11 Jul 2024 16:33
Vauxhall Meriva - Cylinder 4 misfire detected - daveyjp

When my nephew bought a used Corsa as his first car my advice was for him to buy a new coil pack unit, learn how to fit it and keep it in the car, I'd had friends who had suffered the engine light on and misfire and knew it was an achilles heal.

A few months later on a longer trip car threw up EML and immediately developed a misfire. Within a few minutes coil pack changed and he was on his way,

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