Misfiring problem

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Old 04-11-2015, 02:26 PM
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Question Misfiring problem

CAR is a 98 V70 NONE turbo. I got a misfire all of a sudden, Autozone says 7 to 1 miss fire.. I do know that cyl 1 has a misfire due to taking the plug wire off and engine staying same RPM. NOW what I have down to try to fix this is as follows: Plugs, cap & rotor, coil. I have yet to do the wires only because they look new and the insides are clean.. I have no effing idea... HELP!!
 
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Old 04-14-2015, 08:51 PM
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are you getting any check engine light codes? I don't think you can assume a wire is good because its insides are clean, as it could be a broken contact. If that doesn't fix it, pull the plug for the #1 Cyl. Does it look oily or wet? If you do the wires and still no go, I'd check fuel pressure and perhaps the #1 injector. You should get a code if the ECU senses the injector is not working so it could be clog. There are services that use ultrasound (like a jewelry cleaner) to clean the injectors.
 
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Old 04-15-2015, 06:16 AM
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Cylinder 1 has no compression, did a ring test and still no compression. Thinking a valve is stuck.
 
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Old 04-15-2015, 09:12 PM
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Do you have any tappet noises? I think you're looking at a burnt valve or a stuck valve to get zero compression wet/dry. If you pull off the valve cover you should be able to see if the spring is broken or if the valve stem is not actuating when you turn over the engine by hand. Its possible that the valve guide is bad and seized the stem or you have a broken valve spring which you should be able to see from the top. If the valve is moving then you probably burnt an exhaust valve and the head has to come off. Some people suggest on other posts to try Seafoam to see if that can undo the sticking - I'm not sold on that idea so I'd probably go the visual route first. Also read up on replacing the valve cover seal to see your car uses the paint on gasket like the 850s
 
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Old 04-16-2015, 07:22 AM
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If you pull what you are referring to as the valve cover, no valves will move when turned over by hand.

A cylinder leakage test needs to be done but you'll be pulling the head eventually.
 
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Old 04-16-2015, 11:59 AM
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my bad - you are right, the cam assembly need to to come off to expose the tappets so I guess if you are that far, you're 90% to pulling the head. There's a few good vids on Youtube to see the head removal process. (I admit I've never done a head gasket/valve job on a Volvo 5 cylinder - only on a BMW and an Audi... those were traditional 2V OHC set ups - LOL, I still have parts for those cars for eBay!)
 
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