Ignition coil pack problem

[ProDave]

Aveo 1.4 LT

It suddenly started running rough and I quickly determined it's only firing on 3 cylinders, quickly determined the coil pack is only sending out power to 3 out of the 4.

It's this coil pack, so I ordered one that arrived yesterday. http://www.ebay.co.uk/itm/1717648432...%3AMEBIDX%3AIT

The replacement is identical in every way to my original one. But it doesn't work. NONE of the plugs are firing with the new one.

So I contacted the seller and he sent another one. That too is the same, none of the plugs fire.

I've asked my mechanic at the local garage thinking perhaps it needs to be programmed by the diagnostic computer to pair it to the engine management, but he says not.

So I can't believe I have been sent two dud ones, so what is going wrong?

[Mattaveo5]

Have you pulled a plug and attached it to a wire to check for fire against the block? Or used a spark tester?

[ProDave]

Yes I have. that's how I determined one plug on my old one has no spark at all, so with the old one it's running on 3 cylinders.

If I fit either of the two new ones, then none of the pugs are getting a spark.

[Mattaveo5]

Okay. Not trying to question your judgment. It's just very odd that they sent you two faulty coils. Do you have a feeler Guage? You may want to check the gap on the new plugs. I believe I saw a thread here where people received new spark plugs with a gap too far. I believe it's suppose to be a .40. But you may wanna look that up to be sure.

[Mattaveo5]

Correction: recommended gap is .044

[ProDave]

Plug gap is correct, I was surprised how wide it is, I'm used to old school cars with a gap of .025 All plugs look good.

It's definitely the coil pack not sending any power to the plugs.

My problem is I could not find a supplier listing the coil pack for a Chevrolet here in the UK, they are not that common, so I bought a coil pack for a Vauxhall. (They are All General Motors cars, end the engine in my Aveo is definitely used in a number of Vauxhall cars)

They look the same thing, but I'm wondering if we have a daft situation where the Vauxhall one although it looks identical, expects different wiring?

[Mattaveo5]

I'd say that's probably your issue. Current passing through the coil differently than it would the GM coil.

[06T200]

Dave, just for giggles, try swapping around the plug wires with your old coil, could be a bad plug wire causing no spark on the one cylinder??

[ProDave]

It's a coil pack that sits on the top of the engine and plugs directly onto the 4 plugs. No leads involved so no swapping possible

[06T200]

Oops! Just noticed the 1.4. Whole different animal. My bad!