My car is a 98 Civic LX and a D16Y7 motor. My check engine light comes on and is throwing a p1399 code. I believe it is multiple misfires detected. I replaced the cap rotor and plugs and it was good for about a day and a half now its back. I dont have an E.G.R and I checked my valve lash, all intakes were @ .oo8" and exhaust were @ .010". I tried to check resistance at the coil but the screw stripped when I tried to remove it, and I was going to check the .I.C.M. tomorrow. Does anyone have any ideas, help or suggestions ?? Please help..

 

Well, it's more common for misfires to be caused by ignition rather than fuel delivery or compression, so I'd check in that order (spark, fuel, compression). I assume you've checked your plugs?

Also, which cylinder(s) is(are) missing? It might help narrow the problem down.

 

Spark plugs are brand new, E3's . Im not sure which cylinders, I had to look up the code on the internet because its not in the Chiltons manual, it just says multiple misfires detected

 

Okay, to test which cylinder or cylinders are misfiring, start the car up and let it idle. While the car's running, one by one, pull a plug wire out of a cylinder (remember not to ground yourself against anything).

If you pull a wire and the idle drops down a few hundred rpm, that cylinder is firing normally.

If you pull a wire and you don't hear the idle change, that cylinder is misfiring.

Also, if you have more than once cylinder misfiring, pulling one of the last remaining good cylinder's plug will probably kill the engine; it won't hurt anything, it's just kind of annoying to have to go back and start the engine lol.


Also, have you checked the resistance of the plug wires? I believe the rule of thumb is 10 kilo-ohms for each foot of the wire's length.