Mondeo firing on two cylinders - Plugs, injectors or something else?

could be the dis pac (coil).

Can't really help with your problem but the fuel pressure is extremely high, so high that it can go into your skin. My Vauxhall has a pressure release button on the fuel rail and I'd suggest you have a look to see if you can see one before going anywhere near the injectors with a spanner.

Hopefully someone can tell you where it is or say it's not an issue with your engine.

coil pack, air leak at that end, head gasket blown between cylinders.

mrcheerful

Probably not; the paired cylinders in a DIS system are 1/4 and 2/3, because they reach TDC together.

Most likely the coil pack, but when were the HT leads last changed, and are they genuine Ford/Motorcraft ones? It's a wasted spark system, which means there's two plugs fired by each coil, so if anything happens to one of them, the other will stop working aswell.

But having just thought about it, on a wasted spark system 1+4, and 2+3 are paired.

Sound either like somebody's put the HT leads back on wrong, or dodgy injectors (it would be highly unusual for two to fail at once though), or some other mechanical failure.

Start with basics.

First take spark plugs out on at a time and connect to your ht leads. Make sure the ends of the spark plugs are touching something metal on the engine or use a jumper lead to connect them to the engine block.

See if the spark plugs are sparking.

If yes pressure test the cylinders in question.

If pressure test is ok look toward injector problems sounds like no fuel getting through.

Triple check your HT connections at the coil pack. The DIS works 1+4, 2+3 as others have said. The only way that you wont get 3&4 to fire other than HT leads incorrect is blown HG between 3&4.

Injectors are probably fine.

Tim..

Bit drunk here so bare with me.

As others have said, Zetecs run on the wasted spark DIS (Distributorless Ignition System). This means that because both cylinders 1 and 4 hit TDC at the same time, there will be a spark in both cylinders, even though one will be on the compression stroke (which is what you want for power) and the other on the exhaust stroke (which is a wasted spark...hence the name). Cylinders 2 and 3 are the same. I would WD40 all connections on the injector rail and get a compression test on cylinders 3 & 4. Injectors are *not* a weak point on most engines, they are pretty basic by operation and don't tend to fail in pairs. Zetec engines operate in an SEFi fashion where by each injector only fires when the cylinder needs fuel. Injector 3 & 4 failing at the same time is highly unlikely.

I reckon you have a gasket failure between 3&4 leaking compression into each other. As everyone has said, get a compression check, they are simple and cheap. Each cylinder should read *approx* the same...maybe not bang on, but any big differences should be taken seriously.

The DIS pack failing is something you can rule out, because of it would require failure of both coils to f*ck up two cylinders, which would mean all four went!

Do a compression test first. Blown head gasket or burnt valves are possible causes for the cylinders not working.

-- Dave Baker