I have a 99 Integra LS. Not too long ago my check engine light came on and my car sounded like an STI. I knew right away that i had a misfire. So i had the codes ran , and it came up saying i had a misfire in 3 out of 4 cylinders. So i went and changed the plugs, wires, cap, and rotor. Problem solved right? Wrong! The next time it rained, Problem came back. Keep in mind the problem was only there when it rained, snowed, or the ground was just really wet. So yesterday i went and had the codes ran again, and it tells me that all 4 cylinders are misfiring and that there is a multiple misfire at the same time. Does anyone know what else the problem could be? PLEASE HELP!!! Thank you in advance.

 

Check the cap & rotor. It's possible that water is getting in there and causing havoc. Sure you aren't getting any other codes?

Change out or clean plugs as much as possible. It's the #1 overlooked factor in motors that missfire.

Make sure the distributor harness plugs are in good and tight. Would be nice if you had a spare distributor laying around to test out.

 

maybe check the timing. if its all out of timing you may detinate the motor. incorrect gapped plugs maybe

 

sounds like a bad coil. check it if you have an ohm meter, or swap with a known good one to see if it helps

 

check all of your grounds..

 

spark plug wire could be the culprit..i had a bad one that goes bad..

 

I had a missfire issue also... it was oil/dirt/debree build up in my spark wire/plug. To make matter worst there was a oil/water mixture in my cylinder. Changed the gasket and set new wire/plugs and solved teh problem. Hope that helps you.