For over a year now my car has been intermittently misfiring on cylinder 1- usually at idle, most of the time is P0301, some of the time it is just P0300, or sometimes both. But I have taken it to a shop and they couldn't pinpoint the problem anymore than I could.

So sparks, wires, cap, rotor have been replaced and that did nothing, switch wires/sparks no change.
Swapped fuel injectors 1 and 2 with no change.
Compression test show the same numbers.
Plenum gasket is new and lower intake was tested for leaks.
No smoke of any color when misfiring, although its smells of carbon (like when seafoaming) or sometimes lean.

I have replaced the distributor also and that didn't change the problem but from what I have been told it is the only thing left that could really be causing a problem. Any thoughts?

 

How long at idle does it do this before it starts to misfire?
Do you drive on the interstate for longer than 5 minutes?...say above 10 minutes?

 

Well it takes a couple of seconds for it to start misfiring and noticeably be different, but the light wont always come on. I drive on the highway once or twice a week for 30 mins or so. When I am in school its 5 days a week for about 70 (2 trips) minutes each day at about 70-80mph.

EDIT: Got another distributor from a 98 stratus- still having the same problem although I noticed that the IAC plug was disconnected - which oddly enough through no codes. It was only disconnected for about a day or so and I only noticed the difference in performance when I disconnected the power to replace the distributor. Could a bad fuel filter be causing my problems- I know it hasnt been changed in a while, other than that I would be changing random sensors trying to fix this problem.

 

Alternator, random sensor, will of god...help me out here I really would like this fixed.. I'm going to start school soon which means I will have less money and time to work on this.

 

I am not familiar with the 2.5 but I had the same problem with my 420a except in cylinder 4. I could not find the problem, did cam and crank sensors, new wires new plugs almost every sensor, new filters and nothing changed. Finally one day I went to leave for work and it was running really bad and the CEL was flashing so I threw on the code scanner and got the code for a bad coil(p00251?...dont remember). I changed the coil and it has run beatiful ever since then. No more misfires.

 

Curious as to why you got one from a Stratus 3.0L over a 2.5L. I ask because even with the 3.0L swap, the 2.5L distributor is used.
At any time have you disconnected the battery for a few minutes? This will allow the ECU to relearn. Also make sure that the #1 spark plug is gapped correctly and isn't gummed up.

 

Actually I pulled it from a 98 2.5L stratus which was the same engine only with a different plenum and TB - but the plug, wire and injector were swapped from cylinder 1 to 2 with no change. Yes I reset it about once a week because it seems to run better immediately after while it seems to degrade when the CEL is on.

I thought there was a glimmer of hope when I replaced the distributor because I took it to Autozone and the guy told me cylinder 3 misfire but didn't show me scanner. I checked the connections at the cap the next day and looked for any cracks or abnormal scarring on the cap and saw nothing wrong. The next morning I take it to get scanned and it says cylinder one - so yeah....

Going on a year now with the same problem I am going to take a dealer and let them do a diagnostic without replacing anything and if they cant find anything wrong, I am going to leave it alone or pull out the led for the CEL and leave it at that because everyday that goes by I hate my car a so much more.

 

I have a 96 es v6 2.5 i have the same problem i have noticed when i run seafoam through the intake the miss firing goes away for a total of 5 miles or 15 minutes total driving time. i replaced everything in the first post including the engine computer i have no idea how to fix it just to delay. i have even ran a gallon of seafoam through the tank to see if that would help it only get rid of it for a short time. at least i know my fuel system is clean. any ideas??????

 

plus from the factory the distributor for a 2.5 the icm is not removeable and they want over 1000 to replace it i just got anthoer one and used it same results i have not spent that much on the problem becuase i know the junk yard and backdoor people around here but if i was to replace everything new i would have well spend over 4000 just not even fixing the problem there has to be something we are over looking i also noticed the pcv goes into same cylinder that is misfiring i removed the pcv system and blocked it off no fix i assumed the pcv valve was broken and shot oil all over the injector but when in jector is replaced no fix don't know if it is wiring plus also the symptoms i have are missing on idle and extreme misfire when the gas is all the way to the floor above 5500 rpm plus at low rpm on highway my avenger has new injectors new, spark plugs, new wires, new distributor, dist cap, dist rotor, new coil, new icm, new ecu, had new pcv didn't help blocked it off,new thermo stat, new oil pressure sensor i have NO idea how to fix this issue thinking of selling vehicle because of issue but i love it's lines would have been awesome drift care don't know why they made is ff plus if i can fix that problem i wanted to modify the twin turbo set up on the vr4 to fit the avenger and One more does anyone know if the 2.0 transmission will bolt up to the 2.5 sorry to go off subject

 

Well yours has some improvement when you treat it so I would follow that but seafoam really only cleans carbon build up and I dont see why it would give temporary relief to your symptoms unless your car was relearning the fuel mixture when you are driving it or something. It has been suggested that it might be a wiring problem because of the symptoms but the dealer is the only one I know of that can check that and they wanted ridiculous amounts of money that I dont think its worth.

The rev limiter is somewhere at 6000rpm on the car so you may just be feeling that effect at 5500 rpm.

As for my problem I have stopped trying to fix it, because at this point it would be a guess and check thing costing lots of money which I don't have. So I am just changing oil and trying to keep it running because I havent heard of a venge/sebring going over 200K miles and I am at 152K right now.

Stealths and 3000gt are pretty wide, I dont actually think a TT would fit in a venge but if it were me I would ditch the venge and take the stealth.