Hey everyone. Sorry so long, but I've tried several things and have included all details here.


I've been having problems with my '02 Elantra. It shudders and doesn't accelerate well (or at all) going up hill, or attempting to accelerate quickly (like passing a car on the interstate). If I try to push it through these situations it will run worse, engine light flashes, and sometimes will stall. In the past, when it stalled, it would start up again in about 30mins or so.


Codes it has thrown were P304, P303, and P420.


Fuel pump was replaced in November. I changed the spark plugs and wires. After that, it continued to throw the P304 code and run (or stall) as described above. Thought perhaps it was a vacuum leak. I have very few tools, and Autozone said I could use seafoam as a means to tell if I had a leak if smoke came out of vacuum lines as I put it in. I tried this, none came out of vacuum lines that I could tell. I drove it after seafoam, some white smoke came out tail pipe from solution but dissipated after driving a little while, and then I had the shuddering issues and loss of power while driving the interstate. It literally would act like I wasn't pressing the gas peddle, then suddenly surge as if it realized I was... engine continued to run until I pulled over and then it stalled. That was about three days ago. It hasn't started since. It will try to start, and acts as if it's going to... but alas, no go.


I replaced the coil pack. Then the crank position sensor. Still wont start.


I confirmed that I have spark. I tried using starter fluid and it still wont start. I can hear the fuel pump come on when I turn key.




Ideas?

 

First, P304, P303, and P420 aren't valid codes. Do you mean P0304, P0303, and P0420?

P0304, P0303 tells you there is a misfire in cylinders 4 and 3.
P0420 tells you the catalyst system efficiency is below normal threshold. Probably from the misfire in the 2 cylinders causing a rich condition in the exhaust.

Since you are still hetting the P0304, my guess is the #4 plug and or wire is/are bad or you didn't install them correctly. It's also possible the coils are bad.

 

Thanks for responding. Yes.... those are the codes.


I think plugs and wires resolved the P0303 and P0420 code since the only one left before the final stall out was the P0304. Hasn't started since it stalled out the final time. Coil pack and crank position sensor was replaced after that.


Plugs and wires were rechecked to ensure proper installation. coil pack is brand new. Getting really good spark from all plugs when they are pulled out one at a time and attached to the wire during start up attempt.

 

Try checking the throttle position sensor.

 

I don't have any type of meter to check the Throttle Position Sensor. But, pardon me for questioning your advice, doesn't that throw a code if it's bad? The only code I've been getting consistently since plugs, wires & coil pack were replaced is the misfire in cylinder #4.


New update.... I beat the hell out of the gas pedal while trying to start the damn thing and it finally turned over. It runs like hell.... either the misfire has gotten worse or I have it in more than one cylinder now. I'm just guessing, as I'm truly learning as I go here.


It still shudders when I try to take it too fast, but it's not consistent. Sometimes it does it at 20 mph, and sometimes not until 40.


My real concern is how horrible it sounds, there is some sort of knock in the engine that gets worse/louder when I step on the gas..... timing? Engine light hasn't come back on yet despite how poorly it's running.


I have no oil leaks that I know of, nothing left on my garage floor, and nothing that looks wet around the engine.

 

Update...


I removed the fuel pump (motor was replaced by mechanic back in November). But I wanted to see if maybe there was something in my gas, or clogging the filter.


There is a little bit (maybe a few tables spoons) of black granules of pebble looking things at the bottom of the tank. Are these charcoal pieces from the Evap Canister?


There are also a few that I can see through the holes at the bottom of the plastic fuel pump assembly container. I think I can see the fuel filter in there, but I don't know how to disassemble the fuel pump container. I don't want to break it, as these things are expensive. I've done a search on the forum and haven't found any instructions. Can someone please explain?

 

This will be my last update since there really seems to be no interest in my thread.


Got the fuel pump apart, replaced the fuel sock at the bottom since it had holes and was severely clogged.


Tested & cleaned fuel injectors.


Syphoned out horrible looking gas, separated.... looks like a lot of water.


dried out tank with paper towels, rinsed with premium gas a few times, and dried it out again.


Reassembled, put premium gas in it, and it fired right up, runs like a champ.... except I still get the shuddering, hesitation, and stalling issue. No code yet, but it's only a matter of time and I predict that it will continue to be the misfire on cylinder 4.


I will now join other forums where I see better activity and participation.


Thanks anyway.