ANSWERS: 7
  • Those codes indicate random misfire in the cylinders. It could be that the coil is bad and is giving a poor spark causing the misfire at various cylinders. You've already changed everything else from the plugs all the way back to the distributor cap and rotor. That's what would make sense to me.
  • There are three kinds of gasoline engine misfire scenarios, first there is the "under load" misfire and there is the "at engine idle" misfire, and finally there is misfire continuously. All engine misfires exist because one of three things has occurred. First, a cylinder has lost compression, a cylinder needs a certain amount of compression to operate correctly. Second, the ignition system has failed or is failing intermittently, spark is needed at the time of compression to ignite the fuel air mixture. Third, the fuel air mixture is incorrect, proper mixture is needed for the ignition system to ignite fuel properly. If any of these conditions occur in the engine, the engine will misfire. 1. Low or no compression can be caused by a. burned or leaking intake or exhaust valves b. worn or broken piston or piston rings c. worn out camshaft d. wrong weight motor oil was installed holding the cam followers from adjusting e. broken valve spring f. failed head gasket. 2. Ignition system has failed or is failing a. spark plug has fouled or is worn out b. ignition coil has failed c. spark plug wires have shorted e. engine control module coil driver has failed 3. Fuel/Air Mixture is incorrect a. vacuum leak at the intake manifold b. fuel injector has failed c. EGR valve is stuck open d. mass air flow sensor has failed e. oxygen sensor has failed f. air intake boot is cracked common problems: 1. fuel injector has failed or is failing 2. spark plug wire has shorted 3. spark plug is worn out or is cracked 4. ignition coil has failed or is failing
  • changing the ignition coil did not solve the problem. injectors ohm out at 15 ohms. next step??? ignition module or head gasket
  • It appears that your engine misfire is caused by low compression, to confirm do a compression test on all cyliders. You are burning rich because you are not reaching high enough compression to combust all the fuel.
  • okay, first off I read the other answers and the only one that had a clue was sweet tea. I have eight years honda dealer experience and have never seen an ICM cause a misfire, they either work, or dont work. I see that you have already tried the high tention ignition components and the fuel filter. If it is a noticeable misfire my next step would be to check the valve clearnce, known as valve lash. If your valves are out of specs they will cause misfires. While you have the valve cover off during the valve adjustment, check to make sure your timing marks line up. There will be two painted markes on the pully at the front of the engine, one red and one white. Line up the white mark with the pionter in the timming belt cover with the mark in the correct location, you should see three marks on both cam gears, one either side of the diameter of the gear, and an arrow that pionts up(if the arrows piont down rotate the crankshaft 180') With the arrows pionting up the marks on either side of the gears should line up with the machined surface of the head. If your belt has streched your timming would be off and could cause a missfire. If is a non noticeable misfire I would inspect the E.G.R valve and passage ways. It is common on high mileage vehicles fore this system to becom plgged and cause a misfire, however it is commonly acomponied by a P0402 insuficient E.G.R flow. If all this looks good than I recomend performing a cylinder leakdown test, this will tell you much more than a compression test. Now I have a question for you, when was the last time you changed timming belt? If you have not changed it, it should be chaned every 105,000mi. If you have changed it, did throw the misfire codes before or after the timming belt was changed. Your local autoparts store by law cannot clear your trouble codes, however licenced repair shops can. Before you continue to struggle with this problem I recomend clearing the codes and noting the condition at which the codes set. Another option is to go to a licenced honda dealer and they can give you a printout of the conditions at which the codes set. This information is very helpfull to diagnosing the condition. Note: your misfire codes are P0300 random multiple misfire, P0303, P0304 mifire cylinder 3&4 because this is an emmissions code: just because you replaced some parts, the code will not go out on its own, so you may have already solved the problem and don't know it
  • If the ignition coil was faulty you also have codes P0301, and p0302. The coil is attached to all cylinders and hence affects all cylinders, not just 3 and 4.
  • I have a 2001 honda prelude with a p0304 missfire code. I have done a complete tune up along with pcv valve and both o2 sensors. I will replace fuel filter and have a valve lash done to see if that solves my proplem. I post up results

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