2000 civic 4cyl, misfiring cylinder 3, plugs and wires good, is it possible to have a burnt exhaust valve and what would be the best way to find out? the engine light was on and before i could fix it it began flashing, meaning something more major had occured. i pulled the valve cover and assume i will have to pull the head-any tips advice are welcome!!
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Re: misfire cylinder 3
Put the valve cover back on. Get a compression tester and with all spark plugs removed test the compression on all cylinders. They shoudl be aproximately 10percent of each other value. If one or more are low put an once of oil into the cylinder and see it the compression rises quite a bit. If it doesn not then you know it is a valve. If you have two next to each other,with low readings then you have a head gasked or head problem. Good luck.
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Misfire in cylinder #6. Could be bad spark plug, spark plug wire, cop coil, bad intake/exhaust valve, clogged fuel injector or piston/cylinder problem. What's the year, make, model, engine and have you been following the recommended maintenance schedule for new plugs?
Code means there's something causing a misfire on cylinder #5. If you know for sure, and have tested the injector with an ohm meter, only other thing it could be is a faulty exhaust valve if you still have a miss in the engine and it vibrates the vehicle when it goes into overdrive. Do a compression check on all cylinders to be sure. If they are all the same, no burnt valve. If no burnt valve, it has to be the injector faulty.
the misfire on a particular cylinder can be from several reasons
1--- mechanical--burnt valves , loose valve seat insert , hydraulic tappet holding valve open===run a compression test to eliminate mechanical faults
faulty injector, faulty injector tip( blocked) faulty injector wiring, plug, ht lead --ecm
cracked insulation in distributor cap or coil housing
moving a faulty injector to another position will move the miss or simply replace it with a known good unit
There may be something amiss with the piston or valve.. and it's usually the exhaust valve that has burnt/split, allowing compression to be kicked straight out of the exhaust. The symptom of a burnt/split exhaust valve is akin to a misfiring spark plug
Hi, there are 2 common reasons for a single cylinder misfire you have not addressed it: faulty fuel injector and burnt valve.
You need a voltmeter to test the injector:
Check the resistance across the injector terminals. It should be about 12 ohms. If open or shorted, replace the injector. After removing an injector, apply 12 volts DC across the terminals. A "click" should be heard. If not, replace the injector.
If ok, then you need to do an engine compression leakdown test with cylinder compression gauge. if compression leaks down in that cylinder, then you have a burnt valve causing the misfire
Have you done a compression check? I had the same problem on an S-10 Chevy pick up. Found that # 3 cylinder had low compression due to a burnt exhaust valve. No more problems after having valve job done on the engine.
A code P0300 may mean that one or more of the following has happened: * Faulty spark plugs or wires * Faulty coil (pack) * Faulty oxygen sensor(s) * Faulty fuel injector(s) * Burned exhaust valve * Faulty catalytic converter(s) * Stuck/blocked EGR valve / passages * Faulty camshaft position sensor * Defective computer
Possible Solutions: * If there are no symptoms, the simplest thing to do is to reset the code and see if it comes back. * If there are symptoms such as the engine is stumbling or hesitating, check all wiring and connectors that lead to the cylinders (i.e. spark plugs). Depending on how long the ignition components have been in the car, it may be a good idea to replace them as part of your regular maintenance schedule. I would suggest spark plugs, spark plug wires, distributor cap, and rotor (if applicable). Otherwise, check the coils (a.k.a. coil packs). In some cases, the catalytic converter has gone bad. If you smell rotten eggs in the exhaust, your cat converter needs to be replaced. I've also heard in other cases the problems were faulty fuel injectors.
Random misfires that jump around from one cylinder to another (read: P030x codes) also will set a P0300 code. The underlying cause is often a lean fuel condition, which may be due to a vacuum leak in the intake manifold or unmetered air getting past the airflow sensor, or an EGR valve that is stuck open.