Hello all. My 02 GTP sedan was running like crap last week and could feel one or more cylinders missing. Car didn't have a lot of pick up and go. I had my scanner in the console and plugged it in. I got a p0305, miss on cylinder 5. That corner of the engine had a small fire about a year ago from adding oil without a funnel and the engine hot. The plug for that injector is slightly melted. I noticed that if I'm at 85mph and up and floor the pedal the check engine light comes on and starts flashing, then goes out once I let off the gas. I thought it may have something to do with the fire but the next day I had a check engine light and again hooked up my dummy scanner but this time it gave me a p0304, miss on cylinder 4. 4 is on the firewall side of the engine so it kind of leads me away from the whole fire incident idea however I haven't completely ruled it out. They don't use the same ignition coil either. The second day I got it up to 85-90mph (again, only for testing purposes!) and floored the pedal for 5-10 seconds and got the flashing engine light again. This time it gave me all of the following as pending: p0304, p0305, p0300 (misfire on multiple cylinders)
I checked it today with no codes or pending codes even after driving over 100 miles since I purposely made the last codes come up. I haven't been hard on the gas/acceleration since I last forced the codes to appear.
Some more info on my engine:
218K+ on original engine and transmission
Recently replaced air filter (still oem air box)
Believe I still have the oem intake gaskets knock on wood (had the car since 73,250 and haven't had it done)
Plugs and wires changed around 100k?
No engine modifications
Put CLR in cooling system and ran it for about a half hour. Then dumped it, filled with water, ran it dumped it, repeated the water once or twice more, then added 50/50 mix of water and concentrated coolant. This was done two months ago. I've been using prestone green universal for the last 6 years, 7 if I never used dexcool, I can't remember if I did
Oil change a couple of months ago. I have always always used valvoline full synthetic and the last couple of years have only used wix oil filters
I believe I changed the fuel filter a couple months ago during an extensive suspension and wheel hub overhaul
Replaced the thermostat during the coolant change out
Please please please help me with what vectors to head in troubleshooting this. This is my daily driver and I drive over 100 miles every day through the week. Recently money has gotten a little tight and with a baby on the way and due in May I really don't have time and money to spare right now. Any and all help appreciated!!! My wife has been on my case for the last few years and this is the one car that I've been more attached to than any other car as some of you may have also had. I refuse to get rid of it, running or not.
Thanks a lot!
