Discovery 2 V8 misfire

Hi all
hope someone can shed some light on this, car was running fine up to the point of changing the oil cooler, fitted nicely easy job, went out on road test was fine for about 2 miles then seemed to loose power and vibration felt through car. no fault lights on dash. popped into Land Rover garage near me ran diagnostics and pointed to misfire on Cyl 6 replaced leads and plugs without removing plenum (IM) still same fault whilst carrying out further checks it ran sweet for a min while idling then wet bad again, Torn between coil packs and injector issue any one else had this problem as need this sorted.
UPDATE just scared myself reading other posts referencing to slipped cylinders and cracked blocks etc and list goes on!! Oh and now the air suspension has gone up the creek maxed out on one side Ride height adjuster is broken released the air out via the air block, cable tied it back on, seemed to behave itself ordered new adjuster, just rechecked it after drive gone back to high on one side still misfiring though.

can't help in any way except to say check that pot 6 plug/lead then get it to someone who knows what they are doing and get some live data, its not all abotu the stored codes... hope you get it sorted, keep us posted...

Hi Markyzs180
The Landy garage I popped into did a live data check and showed misfire on pot 6, so I replaced the leads and plugs and still had same fault, went back rechecked still pot 6 and on the return journey ride height adjuster snapped. Going out at first light to take off the plenum and check the wiring to the injectors and the coil pack which incidentally was loose when I was changing the leads, which made me think that if the coil pack has been removed before and not put back properly that may be the issue. I'll keep you posted.

The coil pack is electrically unaffected by the mountings, it should operate even if isolated from the engine, as the four coils are fed by two feeds from Fuse 14 and grounded by four ECU firing connections to work the four coils.

As the plugs are fired by a 'Lost Spark' system, you also need to check the opposite plug to that on pot 6, just for completeness.

We lost a cylinder while down in France in 2024, our son's V8 just misfired from startup one morning, and we couldn't find any obvious faults. We had plugs with us but they made no difference, so as we were heading back up country, he drove it on seven cylinders and we got our other son to ship us some spare coils and leads. When we got up to the site the next day the parts were waiting for us.

When he stripped it down, one of the 3-pin plugs on the side of one the coils had got corroded and had a bad contact.

We swapped the coil and it was fine afterwards and has been since.

Peter

Sounds like same thing, all I did was change the oil cooler!! anyway stripped it down swapped round the coil packs and gave everything a good clean, and sorted an annoying water leak just under the throttle body, high temperature silicone does wonderful things still rebuilding at the moment, haven't found anything nasty yet. Let you know if its worked.