Has anybody else had this issue? The dealer cannot seem to figure out the problem. I have a 2001 Hyundai Tiburon. It is a five-speed with about 92,000 miles on it. It is still under warranty, so I am hoping to get this resolved.

When I have the car parked in my garage overnight it is fine. However, if it is outside overnight and it rains or I leave early in the morning when there is a lot of dew on the ground and moisture in the air, the car runs extremely rough and misses out. Then the check engine light comes on. It has to be the moisture getting into the spark plug area somehow. This will continue for about 10-15 minutes until the moisture evaporates from the engine heat I am assuming. The check engine light will stay on for a day or two and then it goes out. I have taken it to the dealership for diagnosis and they read the codes and it just shows a misfire. Please help!

 

Well the funny thing about that is that if the code IS showing a missfire than something is not operating within original specs so the dealership should do what is neccessary to find out whats going on. Even if its a maintenance issue that you need to do they should still be able to tell you that. When is the last time you did a tuneup? Plugs, wires, and even changing the fuel filter and putting injector and fuel system cleaner in? A friend had a similar issue and he did these things I mentioned and it was back to normal.

 

First what was the misfire code? Was it a po300 which is random misfire, or does it pertain to a certain cylinder? A po300 can be caused by water in fuel.When a vehicle sits water is heavier than fuel so it goes to the bottom of the tank.Now whats at the bottom of your tank? The pickup for the fuel pump.If it pertains to a certain cylinder then it could be a number of things.Possible plug wire,coil,injector,sticking valve. Compression is the easiest test to do.Is your vehicle a 4cyl orv6? Look on your paperwork and see what the code was.Let us know.

 

in my experience the most common faults of missfire on the coupe are ht leads or the coils sometimes even the plugs but first i would check the leads for tracking to earth![8D]

 

First we need a code to diagnose it properly .You can throw alot of money on a guess.

 

With 92k miles, it sounds like it's time to change the spark plug wires. Here's something to check: When it is moist outside and the car is running rough, look under the hood after dark. If there are sparks around the plug wires or the coils, that's your problem. I had an old Dodge Dart and when the wires went bad, it was a pretty cool light show under the hood after dark. (You may want to try it even when it's not moist.)