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Discussion Starter #1
This is on a Z12XEP.

I just replaced the timing chain, got everything back together and am now getting a misfire on cylinder 4. I've swapped spark plugs round, and they seem gapped correctly. The engine isn't blowing at all through the oil cap and the water and oil are clean. There seems zero power in the 4th cylinder 100% of the time judging by what it sounds like, though I could be wrong. The injector only gives a fault code when unplugged. I have oxygen sensor fault codes from before I did the timing chain, apart from that just the cylinder 4 misfire. There is oil in much of the wiring including the coil pack plug which I've tried to remove with white spirit. I very gently stepped on the coil pack when it was unplugged, so got a second hand one to replace it which was damaged at the cylinder 4 end when it arrived, but it runs the same with that one.

The engine moved quite a lot when I was working on it, and I used the timing setting tools when torquing the replacement sprockets.

I have a compression tester coming, and another coil pack, and oxygen sensors to go in soon.

What are my options? Is it most likely both coil packs are damaged on cylinder 4? Is it possible there's wiring such as the pinking sensor that got crushed against the bulk head? Although the coil seems most likely I can't see what else could really have gone wrong. Help would be much appreciated!
 

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Hi, swap the coil packs around from say 4 to 2 to check if they are ok. Check that your timing is 100%correct before you go any further

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Discussion Starter #3
Hi, swap the coil packs around from say 4 to 2 to check if they are ok. Check that your timing is 100%correct before you go any further

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Thank you for your advice.

The coil packs are all in a single unit, surely? It's not possible to switch cylinders?

As for timing, I set it while doing the engine. Do you mean take the rocker cover off, lock things with the special tools and redo the timing again, as that needs replacement bolts again. Isn't the only way it could be out on just one cylinder is if the camshaft is twisted? Is that really a possibility?
 

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Camshafts don't twist... they snap! Could be a faulty coil pack, ones if worked on are single units

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Discussion Starter #5
So it's possible to dismantle the coil pack into 4 separate units? How does one do this?
 

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No. What I mean to say is the ones iv worked on are single units. If yours is all in one then not able to separate. You could take all the plugs out and test them by turning over the engine and seeing if you get a spark. But then again if they are not under load they tend to spark better.

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Discussion Starter #7
No. What I mean to say is the ones iv worked on are single units. If yours is all in one then not able to separate. You could take all the plugs out and test them by turning over the engine and seeing if you get a spark. But then again if they are not under load they tend to spark better.

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Ok, thanks Dan! Much appreciated!
 

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A misfire will be indicated on an obd reader. You could check to see if temp on each header is hot

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But surely if you can time an engine then all this should be well known

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Discussion Starter #10
But surely if you can time an engine then all this should be well known

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I did the timing according to the procedure in the Haynes manual. I am using an OBD reader, but it doesn't say anything about the misfire except that is on cylinder 4, and I can't see what is causing the misfire.
 

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Ok well either spark, fuel or compression. Try swapping an injector over


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Discussion Starter #13
The temperatures of the coils are all about 12C, while the engine temp is 55C, ambient temperature 7.5C. Since they are all the same this means they are all likely working, I presume?
 

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Temp of the coils? Not likely to damage an injector when doing the timing.

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Discussion Starter #17
There's definitely a misfire on cylinder 4 though, you can hear it clearly and the fault code is there for it.
 

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Well like if said either fuel, ignition or compression. Can you take a video of it running?
Check all connections to everything. Clean all contacts to any electrical connectors you may have unplugged

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Discussion Starter #20
Well like if said either fuel, ignition or compression. Can you take a video of it running?
Check all connections to everything. Clean all contacts to any electrical connectors you may have unplugged

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I'll try.
 
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