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New to the forum because my son has a 99 Honda Civic LX. We have been dealing with a misfire issue for a long time and have had four different mechanics try to fix it. The code says its misfiring on a couple of cylinders and when the engine light is on it runs rough. Here is what we know and what we have done:

• New Distributor (new cap and rotor)
• New Spark Plugs and Wires
• New ECM
• Valves Adjusted
• New fuel filter
• New Fuel Pump

Whenever we replace anything it runs great for 20 miles or so and then starts running rough and throwing the check engine light. It sometimes go off on its own and runs fine. We have put a ton of money into this and at are our wits end. Any help would be really appreciated!!!

 
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Got codes?
Got freeze frame data?
Got any specific driving pattern that makes the problem happen?


Ever check for water in the tank or fuel rail?

 
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Havent checked for water in the tank. We have ran multiple tanks of gas through the system, so I would assume the water would have been run through the system by now? Maybe not. Not sure how to check or to fix it.

No particular driving patterns, just city driving.

I don't have the code number but its always a misfire in multiple cylinders code.

 
Rep Power: 518

Water was just a thought, it can be maddeningly baffling to chase if nobody thinks of it.

Water sits on the bottom of the tank and slowly sloshes around to be (somewhat) randomly picked up by the pump, and sent to the fuel pipes. Your fuel system has a return pipe so any water that didn't go through the injectors will get sent back to the tank--- to be sucked up again later on.

Get a quart jar or so fuel sample and let it sit still a while, see if anything separates out.

A fuel sample taken from the pipes in the engine compartment may or may not show water....because water sits under gasoline. If it shows up in a sample, then great-- you now know what the problem is..... But it doesn't always work like that LOL.

My (personal) best bet is pulling the pump and sticking a (sealed) light to the bottom of the tank, I can easily see a layer of separation between different liquids this way.


Got the old filter? If it hasn't been drained yet you may be able to tell if water was in it as it drains from the inlet side.

Maybe take off the inlet line off from the new filter and drain the filter into a glass jar, see if any water sits on the bottom?