I am experiencing what seems to be an occasional misfire in my 02 Protege5. I just did oil change, spark plugs, and i did a seafoam treatment to the vaccuum system as well. Prior to doing the oil and spark plug change, I also added seafoam to the crankcase and fuel system to clean things out. The misfire seems better but still happens when I first put the car in gear in the morning. I am in Rhode Island, so it is cold here right now. When I start the car, the "choke" works fine with high RPMs initially and gradually works its way down. It does not misfire while idling in park, even when first started. It's only when i put it into either reverse or drive the first time. When i drive away i might get a few sputters in the first 2-3 min, then when the car warms up it's pretty much fine. however, even then sometimes when I stop at a light with car in gear idling it will skip once in a while. Timing belt and water pump were done at 105k, the car currently has 130k on it. My next move is coils and wires.

The reason for my post is I have read that EGR valve and/or idle control valve could cause similar conditions. I have no check engine light at all, i drive the car everyday, and it's fine at RPMs over 2k. This only happens at RPMs below 2k. Even on the highway, if i give it alot of gas it will down shift and run perfectly, no skips at all. So i don't think fuel filter/pump would be the cause.

Any help would be appreciated!!

 

135 views and no one has any input? well anyway, it was really cold here yesterday and on startup after a minute or two it started misfiring bad while in park. luckily, it triggered check engine light so i pulled the codes and had misfires on every cylinder along with a multiple misfire code. nothing else. after some additional research i seem to have discovered that the coils and wires on these cars are a bad design and become very problematic with age. so i did order a new set of coils and wires which i am hoping will rectify the problem. The car has been running great all summer, then the cold weather came and this started happening. today was actually over 50 degrees and the thing is again running perfectly. not one skip or misfire this morning or on my lunch break. so the cold weather is triggering this misfire somehow. i will replace the coils and wires when they come in and report back if it clears up the misfire. i can't imagine that all 4 injectors are bad all of a sudden, or that it could be a major issue. so i think i'm close to the resolution. The car doesn't blow any smoke or anything like that either.

 

Or faulty plugs

 

i just put brand new NGK plus in it, and it was doing this before i replaced the plugs

 

You could try cleaning the idle air control valve and the throttle body. Also, replace the PCV valve.

A random cylinder misfire probably isn't caused by spark plugs or wires - unless they all happen to go bad simultaneously. I had a very bad random cylinder misfire problem a while back. After spending hundreds of dollars and dozens of hours researching, cleaning various parts, replacing various parts, resetting codes, reading codes, researching again, etc etc etc, it wound up being a stuck valve in the gas return line which took all of 15 minutes and $30 to fix.

Random misfires can be caused by dozens of things, but the throttle body, IACV, and PCV are common problems. They're also cheap and easy to clean/replace.

 

I had exactly the same thing, took the dealer 2 weeks to investigate with no results, got the car back and I figured the gas tank had too much moisture and 3 bottles of STP water remover and a few gas refill solved it.