Vauxhall Corsa-C Forum banner

Cylinder 4 misfire after timing chain replacement

9K views 69 replies 7 participants last post by  Zelphium 
#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!
 
See less See more
#36 ·
I've checked the timing and it seems to be spot on on the inlet side and slightly out on the exhaust side, but not what I'd expect is enough to cause a problem, and again, it's only on one cylinder that there's a problem, the others seem to run fine.

Timing sensor disk:


Camshaft timing:


Exhaust timing closeup:


Cams top down:

 
#37 ·
The silver stuff was literally resting on the cam, and would surely have fallen off if the engine was running. I think it's probably just a red herring and some paint fell onto the cam, as it had the consistency of either decomposing paint or very thin chrome plating.

Could this be something as simple as the type of oil I've used? I did an oil clean thing before I drained it, then refilled it with 5W30. If it had thicker oil in previously could it now be causing valve failure, such as through a leaky tappet, to the extent there is no pressure in one cylinder?
 
#39 ·
The camshaft and the crankshaft were locked the whole time I was working on the engine. I think the valves might well be damaged but I can't see what I've done that could have damaged them. They've never been out of timing.

I'm really struggling to get the cylinder head off. The bolts on the exhaust manifold are snapping off, the heads have rusted away and all are seized even with lots of WD40. The inlet manifold doesn't seem to want to budge, having followed the Haynes manual removed the only fastener I could see behind it which turned out to be some kind of earth instead. I think will have to take the radiator off to fit a socket onto the exhaust manifold but that probably requires draining the air con which I don't have the equipment for. And at the end of that I've got to recondition the cylinder head, which I've never done. This is seeming like a monumental task doomed to failure. It's my first car in 10 years, I've been off sick for that long and been utterly broke and I don't have the money to do anything but fix it cheaply myself so I can start a new job. And my bad back is killing me trying to do this. Every step seems to require new tools and parts which then take ages to arrive. It took me 3 days to get to the timing belt in the first place, and another 3 to replace it and get everything back together. I've done major work on other cars I've had but they were 10 years older. This job just seems to be a mystery, and it's been a real fight at every stage. But if I can't get the cylinder head off I'm stuck. And I still have to figure out what the basic problem now is. It seems the valves randomly decided to destroy themselves.
 
#46 ·
You can't take the cylinder head off with removing the exhaust manifold as you need to get to the oil filter housing, I think, before you can remove the cylinder head and the exhaust manifold covers the bolts for that.

Three of the bolts for the exhaust manifold are recessed into hills that are too narrow for my sockets, any ideas?

Three studs have snapped off, one bolt came off, one nut is rusted smooth and one rusted so the socket can't even be hammered on. Any ideas would be appreciated. Should I just drill them all off? I've soaked them overnight with lots of WD40 and tried to heat one of the ones that snapped off.

I have managed to move the radiator so I have some access, but the air con means it's not possible to remove it, though there's probably no gas in the system.

Also, the dip stick seems stuck. It won't even hammer out from the other side. Ideas on this would be appreciated though I'm speaking out with WD40 at the moment.
 
#50 ·
I'm waiting on a very long socket to try to get the exhaust manifold off, so I've had the last two days off. The studs are snapping off though, even with WD 40 and heating, so I've got a lot of them to remove, but the head is almost off and then I can see what the problem is!
 
#52 ·
Thanks, Dan!

I managed to get the cylinder head off! Feeling quite pleased with myself.

I guess this is good and bad news, the head gasket is intact and the valves look fine. They pop open and closed the same as on the other cylinders, and don't appear damaged. This wasn't quite what I was expecting. What now? Logic tells me to put it all back together and see if it still misfires but that's far too long winded and I know it probably would misfire still.

What could be the cause of the lack of compression. What should be my next step. I'd really appreciate some advice here.

I could send the cylinder head to be reconditioned, but there doesn't seem to be anything wrong with it and that's a lot of money just on the off-chance that there's something wrong with it.

35318
35319
35320
 
#56 ·
I wanted to suggest petrol testing, not water, but if it leaks with water ... Test all cylinders!
If you’re so far and remove the valves, lap them all. Change valve seals. There’s an excellent youtube video about valves lapping, search for cylinder head 105 - valve job basics.
 
#59 ·
That light area does look suspicious doesn't it? The timing has never been out, though. I think the timing tools were in the whole time I was doing the car. The light patches look in real life like discolouration. There isn't any actual damage visible to my eyes. I'll check on the piston in the morning though. It's possible I made a mistake and moved valves or cylinder while the tools were out, but I don't think it happened. It would explain why there's now a misfire though.

I really do need to do this as cheaply as possible, so I'll try to do it myself. Thank you very much for the advice and the video link!
 
#60 ·
How much do you think it would cost to have the valves reseated professionally? IT's something like £200 to have the cylinder head refurbished according to the ads on e-bay. If it's just a couple of valves am I likely to be able to get it done locally for a lot less than the full refurbishment? Where should I be looking to get quotes from/get it done?
 
#61 ·
There are indeed corresponding marks on the piston. Not dents so much as silver marks. And it fits in with the engine being locked into TCD on pistons 1 and 4. Possibly when I was putting the camshaft locking tool in I did it. I'm so stupid! But you live and learn. Hopefully it won't be too expensive of a mistake. At least I now know what happened, despite my denials to the contrary. I couldn't have done this without all the help from everyone on here, so a big thank you to you all! It's not over yet, but hopefully the end is in sight.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top