I do have an issue with my 2001 Ford Focus LX,(140K miles) just bought it from a dealer... it was driving fine at first, with no problems, now 3 weeks later - it is driving rough, poor acceleration, shaky motor... etc.
Here's what I did:
I scanned the code and it is a P0303. I looked at the spark plug, it was fouled, carbon, no oil.
I replaced all spark plugs with OEM, also new spark plug wires, and a new coil pack.
I also replaced the fuel filter, it was very dirty. Also a new air filter... drove it and as long as it is not under load, acceleration, it is okay, but still has the hesitation and will eventually throw the same code.
I also did a compression test, they are 180+ on all 4.
I looked at the new plugs and # 3 is black and fouled, others look okay.
There is spark on all plugs.
I am thinking it may be a bad fuel injector on # 3.. other trouble shooting areas, like a vac leak, EGR valve seems they would affect all cylinders.
I have heard of bad valve seats on these cars but can't confirm.
Appreciate any help! THANK YOU![dunno]
Here's what I did:
I scanned the code and it is a P0303. I looked at the spark plug, it was fouled, carbon, no oil.
I replaced all spark plugs with OEM, also new spark plug wires, and a new coil pack.
I also replaced the fuel filter, it was very dirty. Also a new air filter... drove it and as long as it is not under load, acceleration, it is okay, but still has the hesitation and will eventually throw the same code.
I also did a compression test, they are 180+ on all 4.
I looked at the new plugs and # 3 is black and fouled, others look okay.
There is spark on all plugs.
I am thinking it may be a bad fuel injector on # 3.. other trouble shooting areas, like a vac leak, EGR valve seems they would affect all cylinders.
I have heard of bad valve seats on these cars but can't confirm.
Appreciate any help! THANK YOU![dunno]