[ShUpAC]

Hello to everyone,

I am freaked out right now, because this morning when i turned on my car I had the check engine light come on. The car did feel different than other times, but it was driveable. At first, the light was flashing but after 3 or so seconds it became solid. I pulled over as soon as I could to turn off the car and hope for the best.. Needless to say, the light obviously became lit once again after I turned on the car.

When i got home, i did they key maneuver to check for the error code and it came up with:

0300.

The reason why I am very worried now is that my warranty expired about 10,000km ago so any repairs that have to be done have to be paid by me.

Any suggestions on what it could be?

(did search the forums, but with no luck)

Thanks in advance

 

[Rambit]

I'm assuming the code is P0300 - Random Misfire Detected or Multiple Cylinder 1 Misfire.

There may be a chance this code can be reset after three good trips. What's the mileage (kms) and service history of your car?

Here are the possible causes:

(K343) ASD RELAY OUTPUT 2 CIRCUIT
INJECTOR CONTROL CIRCUIT
COIL CONTROL CIRCUIT
IGNITION WIRE
SPARK PLUG
IGNITION COIL
FUEL PUMP INLET STRAINER PLUGGED
RESTRICTED FUEL SUPPLY LINE
FUEL PUMP MODULE
FUEL PRESSURE LEAK DOWN
FUEL INJECTOR
ENGINE MECHANICAL PROBLEM
PCM

You should start with the obvious like checking your plugs etc. If you do a lot of short trip driving without the engine fully warming up you could have a high carbon build up. Anything beyond this will require the StarScan.

Here's some things to consider:
​

- Visually inspect the engine for any of the following conditions.
- Worn serpentine belt
- Binding Engine-Driven accessories: A/C Compressor, P/S Pump, Water pump.
- Misalignment Water pump, P/S Pump and A/C Compressor pulleys
- Corroded PCM power and ground circuits.
- Improper CKP, CMP, MAP, and TP Sensor mounting
- Poor connector/terminal to component connection. i.e., CKP sensor, Fuel Injector, Ign coil, etc.
- Vacuum leaks
- Restricted Air Induction system or Exhaust system.
- Internal engine component failures.​

Even though you didn't mention going into limp mode, have a look at this TSB covering this code - http://www.wkjeeps.com/misc/LX/TSB/TSB_0901006.pdf.

You're most likely out of warranty, so if that's the case it'll cost you for labour and materials.

Good luck and keep this thread updated!

Bernie​

 

[ShUpAC]

thank you for a quick reply


the car has 130,000km on it as of this morning. I should mention that my car had been giving signs for a while now.. every now and then when i'm stopped at a red light the RPM would start moving up and down from 0500 to maybe 0700 and back down... it would feel as if the car is shaking.

I think I took pretty good care of the car.. oil changes on time, followed service manual (pretty) closely.

I had the spark plugs changed on Friday, so I'm not sure if it has anything to do with that.. as I said, the car had been doing this before but i don't recall the engine light come on.

When i turn on the car in the morning (either in cold or warm weather), the RPM stays high but goes back to normal after a couple of minutes of driving. I've been reading about carbon buildup.. Could this cause cylinder misfires?

 

[Rambit]

Make sure you check all wiring for signs of deterioration, good contact etc. Probably would be a good idea to get some injector cleaner too, and yes carbon buildup can cause this.

Bernie

 

[ShUpAC]

thanks again, very much appreciated.

seeing as you know your way around these cars, would you say it would be okay for me to drive around like this for the day? like i said, the car seems to run just fine even when the check engine light is on.

also, if you could give me your best guess on how big of a bill I'm looking at if i were to take my car to the dealership to get that TSB done?

 

[Rambit]

thanks again, very much appreciated.

seeing as you know your way around these cars, would you say it would be okay for me to drive around like this for the day? like i said, the car seems to run just fine even when the check engine light is on.

also, if you could give me your best guess on how big of a bill I'm looking at if i were to take my car to the dealership to get that TSB done?

I don't think it's a problem driving around like that and there's a chance after three good trips the code will reset. Probably about the worst is your emmisions will be out of whack. Hey, check your air filter for signs of obstruction and whether it needs to be changed too!!!

Sorry, no idea what the cost would be either.

Bernie

 

[Northern Rider]

Since you just had the plugs changed, I would look carefully at that work. Check all plug wiring; make sure all plugs were "snugged in" correctly.

Definitely put fuel injector cleaner in your gas.

After checking this, if your car gets mainly stop-and-go city driving, take it out for a good highway run.

 

[ShUpAC]

i just bought a can of that SeaFoam cleaner... so many people swear by it. I'll try it out tonight or something, cause i've hear it smokes like crazy..

it's either try this out and see what happens or pay the dealer big money to fix the problem

 

[nofear365]

Sounds familiar...

http://www.300cforums.com/forums/general-discussion/59672-bad-misfire-car-barely-runs-now.html

My post from a few weeks ago. BTW - no resolution as of yet. It hasn't happened since then either. I bought 16 new OEM plugs. I'll install them when I have the time.

 

[djgera2003]

I have the same problem right now on Cylinder 7 p0307. I changed the plugs, no luck. A member on here named "Flashman" contacted me and he had the same problem 6 months ago. The cause was the Carbon buildup on the Valves. It cost $700 (in Canada) to fix. I just made my appointment at the stealership for Friday. I am not a happy camper right now.

 

[ShUpAC]

I have the same problem right now on Cylinder 7 p0307. I changed the plugs, no luck. A member on here named "Flashman" contacted me and he had the same problem 6 months ago. The cause was the Carbon buildup on the Valves. It cost $700 (in Canada) to fix. I just made my appointment at the stealership for Friday. I am not a happy camper right now.

that seriously blows the big one.. i noticed problems while i was still under warranty, i should have had that checked out right away at:

i drove around earlier again, and the check engine light went off by itself, without me doing anything but driving faster, and reving the engine. I'll still try the Seafoam stuff.. i guess it won't hurt.