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2000 Civic sudden misfiring problem. Help!
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m1man
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Jan 11, 2010, 9:24 PM
Post #1 of 5
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2000 Civic sudden misfiring problem. Help!
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2000 Honda Civic, SOHC base 4 cyl engine with 130k on it. Recent history: Engine apparently has a minor coolant leak that caused the engine to overheat significantly. Car has been running fine since except for coolant disappearing quickly at first following the overheating incident but recently had slowed down to where it needed to only be topped off weekly. I suspected a leaking head gasket or cracked head but no white smoke or other proof so...
Now to the current problem; The car started normally on a cold 20 deg morning (that is cold here in Alabama), the car ran normally for 5 miles then as the car accelerated from a stop, it began to run very roughly and vibrate and had no power.
Now, what I have found and done so far: The two middle cylinders (2+3) were dead as I could pull both spark plug wires off while it idled and it would make no difference at all, although the plugs were getting spark as you could see the arcing as I pulled the wires off. The spark plugs appeared normal except the 2+3 plugs appeared slightly damp as though the cylinders were getting fuel but not firing. A compression test showed #1 cyl at 160 psi, #2 at 175, #3 at 180 and #4 at 200, I checked this twice with the same readings. I decided to rush headlong, foolishly and pull the cylinder head, thinking that although I had no real proof, the head gasket was probably blown between 2 and 3 and possibly 1. The head gasket shows no sign of leakage, head and block are not warped (checked with a straight edge and feeler gauge), no visible damage or cracks in the cylinder head, no water in the oil or oil in the water.
Thoughts, possibilities and hope for a diagnosis: My reasoning was that there was a good liklihood that the gasket was already leaking and because there were suddenly two cylinders with the same problem, I could discount the cause being the fuel injectors or spark plugs. I had checked the distributor cap and rotor for signs of arcing, damage or carbon, everything looked very good. Valve clearance is good. I am now left with the following possibilities (that I can come up with), Distributor is bad somehow causing two cylinders to fire perfectly but the other two not at all. Two of the fuel injectors or two spark plugs stopped working at the same time. Lastly, there is the possibility of one of the two vacuum hoses leaking that attach to the bottom of the intake manifold just below the throttle body and between the two ports that lead to the 2 and 3 cylinders, this could lean out the air fuel mixture to just those two cylinders could'nt it?
That is all I have. I am about to spend a few hundred dollars on the parts needed to put it back together without knowing what the problem is. Give me hope and tell me what the problem is. Thanks! 
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re-tired
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/ Moderator
Jan 11, 2010, 9:47 PM
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Re: 2000 Civic sudden misfiring problem. Help!
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There are many places a head could crack that you cannot see. Have a machine shop pressure check the head and a zyglow test . It's a chemical that detects the faintest crack . Also those eng's are known to have head bolts stretch .
LIFE'S SHORT GO FISH
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m1man
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Jan 12, 2010, 5:57 PM
Post #3 of 5
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Re: 2000 Civic sudden misfiring problem. Help!
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OK. I agree but the main issue is what is causing the 2 and 3 cylinders to be dead? I don't want to spend any more money putting it back together if there is some other fatal problem. Can you give me any ideas that I have not already thought of or show me where my logic is off?
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Sidom
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Jan 12, 2010, 8:24 PM
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Re: 2000 Civic sudden misfiring problem. Help!
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Well, you kinda jumped the gun on this one. There really isn't anything you can do at this point other than get the head pressure tested and reassemble it and go from there. From what you posted I really didn't see a reason for pulling the head for a misfire.
It sounds like you did have a head gasket leaking but with those compression reading those cylinders should've been firing and that problem needed to be found before the tear down.....
I have seen intake gaskets split on those & kill a cyl or 2. I don't know if you happened to look at the old gasket to see if it was in one piece or if it was broken.....
Like I said. At this point all you can do is reassemble the engine and hope it was a bad gasket, if not, once it's running then you'll have to diagnose the misfire...........
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re-tired
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Jan 12, 2010, 8:34 PM
Post #5 of 5
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Re: 2000 Civic sudden misfiring problem. Help!
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You could have a hidden crack between the two intake runners .Or if the head bolts did stretch you would lose the clamping force on the head gasket , the result is same as a blown gasket . Did you happen to see if all valves open the same amount ? You could have a worn cam lobe(s). Rare but it has happened. The only way to find your problem is a methodical process of elimination. Start with one test and proceed to next . If you hop around shooting for the quick fix you will end up chasing your tail . Good hunting . 
LIFE'S SHORT GO FISH
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