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[MeanGene]

I have a misfire on cylinder 3.  The code says misfire but I see no spark at all.  The coil pack, plugs and wires are all new.  What else could be the issue?  This is on a 98 3.0L Cadillac Catera.

[JamesV6CDX]

Just because the parts are new doesn’t mean they can’t go wrong, even though it’s less likely

Worth doing a compression test too

[BazaJT]

Is it only on cyl 3 that there is no spark?If you're getting a spark at the other plugs try swapping a plug lead from one of the others and see if the problem moves.

[Kevin Wood]

Not sure if a Catera of that year will have the later style coil-on-plug coil packs. They changed a lot earlier than ours.

If you are getting a spark on the other plugs, then it's down to the coil driver, which is built into the ECU, or maybe a broken connection between the coil pack and ECU.

[Doctor Gollum]

'99 on were Dbw 3.0

[MeanGene]

It uses the coil pack with all 6 in a brick. There is a misfire on 6 but it has a spark and 3 no spark at all.  I tested the plug wire with an ohm meter and it sould a similar reading to other sires of the same length.  I still have the old coil pack, although a pain to change, I think I will try that first.

[Enceladus]

It's a wasted spark system across three cylinder pairs 1-4, 3-6, 5-2 So 3 fires at the same time as 6 and vice-versa. One of the pair would always be on the exhaust stroke so the unnecessary spark in that cylinder is 'wasted'. Hence a coil pack fault on cyl 3 usually affects cyl 6 etc.

Make sure that plug wires are pushed fully home on the coil brick pack. That said I've seen an out of the box fail with an aftermarket coil pack. Very irritating given the effort required to replace the coil pack on some models.