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Almost stalled when starting a couple of months ago then started running hesitently. It felt as if it was running on 5 cylinders. The revs would jump around + or - 100 revs on tickover and I could feel an engine vibration through the speedo pedal when accelerating. If I keep the revs high / gear low it is ok just a little sluggish, Sluggish when accelerating normally but ok when cruising. At the same time the computer wouldn't register mpg properly although it was nice to see 999.9 mpg.
Have taken out the front three plugs and they looked ok, then ran with each of these disconnected with no noticible difference. I thought if I ran without the bad plug I would notice no difference but if another was disconnected (running on 4) it woud be obvious. So I'm confused, not sure if it is running on 5 now.
As I've been of work for a couple of months after an operation a trip to the dealers is not an option ( I'm also about to try a glue repair on the ABS toothed cogs for the same reason).

Would welcome advice, simply put with pics if poss as I'm no mechanic,

Thanks
Tom

Do I have a voodoo car or something?

I'm no mechanic either, and the following applies to the 194bhp ES9J4 engine only, not the 210bhp ES9J4S:

The difference between 4 and 5 cylinders is VERY hard to tell. You can however disable each cylinder without taking the inlet manifold off - the rear cylinders can be disabled by pulling the relevant HT lead and the front cylinders can be disabled by pulling the injector connectors located just behind the coil pack. I was going to try pulling 2 cylinders at a time to make any difference much more noticeable.

I can't see how the trip computer would be affected by a non-operational cylinder - It wasn't when I was fiddling with mine earlier this week killing sparkplugs and injectors...

If you have access to an oscilloscope or very sensitive analogue voltmeter, you can check the operation of the coils and if it's an ES9J4, the rear plugs by simply holding the probe next to the HT leads (the probe can pick up a few volts through induction). Likewise if you crank up the sensitivity you can check if the injectors are being fed electricity.

If you have a cylinder where the injector's working but there's no spark, you will be able to smell petrol in the exhaust, especially with a cold engine.


First things first I'd suggest new spark plugs all round to rule out something cheap. To get to the rear bank you'll need to take the intake manifold off. To do that you'll need a gasket from the dealer. For the ES9J4 it's part 384K7 (£1.66). For the ES9J4S you'll have to ask the dealer

Maybe I should mention it's a 'W' reg 2.9 V6 estate.

Thanks mjb, I'm going under the bonnet tomorrow so I welcome all suggestions, I will get an inlet manifold gasket from the dealer and a set of plugs from Halfords or similar. I'm afraid an oscilloscope isn't an option as I have little tech knowledge these days. I did a complete engine swap in a mini 30 years ago but everything was much simpler then.

Anyone got any pics for guidance as I get annoyed with the Haynes manual, it never seems to show anything you need clearly.
Tom