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2002 Ford Escape P0303 Misfire: Diagnosis and Fix for Cylinder #3

Model: 2002 Ford Escape Fault Code: P0303 Posted: 2012-03-02 08:59

I own a 2002 Ford Escape with a 4-cylinder, 5-speed manual transmission. The Check Engine light activated, and the diagnostic code read P0303 — indicating a misfire in cylinder #3. I inspected the spark plug and found it to be in normal condition. It is a Motorcraft plug, though I did not verify the model number. The electrode appears slightly off-center relative to the ground contact. This issue has been recurring, so I'm looking for guidance on what else to check. Any insights into potential causes or troubleshooting steps would be greatly appreciated. Thanks in advance, Steve Pheasant Hollow Farm

Related fault codes
P0303
Comments (7)
Anonymous 2012-03-03 06:50

For more information about P0303, refer to this official OBD-II code guide: http://www.obd-codes.com/p0303

Anonymous 2012-03-06 05:43

Mohawkmtrs wrote: Check out this resource for detailed P0303 explanations: http://www.obd-codes.com/p0303 Thanks! I have the Haynes Repair Manual, which lists two Motorcraft spark plug models: AZFS-32F and AZFS-32FE. According to it, cylinders 1 and 3 use AZFS-32F, while cylinders 2 and 4 use AZFS-32FE. I'm confused about this difference — especially since I don't have the original owner's manual. I contacted a local Ford dealer, who only listed SP-478 plugs at $11.48 each. What are the key differences between these plug types? Steve Pheasant Hollow Farm

Anonymous 2012-03-06 08:14

I generally trust manufacturer specifications over aftermarket manuals. The original Owner's Guide (3rd printing) specifies that the AZFS-32FE spark plug is used for the 2.0L DOHC Zetek engine in this model. It also notes: "Refer to the Vehicle Emissions Control Information (VECI) decal for correct spark plug gap settings." and "If a spark plug is removed for inspection, it must be reinstalled in the same cylinder. If replacement is needed, use only plugs with the service part number suffix as shown on the engine decal." I recommend asking the parts specialist whether these plug models are still current. As for differences between plug types, I'm not certain.

Anonymous 2012-03-06 09:11

Differential spark ignition systems (DIS) and waste spark designs may explain why different plugs are used. Here's a technical document explaining how these systems affect spark plug wear: http://www.ngksparkplugs.com/docs/tech/...0Plugs.pdf

Anonymous 2012-03-07 12:48

Thank you both for the helpful insights. Steve Pheasant Hollow Farm

Anonymous 2012-03-08 06:03

And Steve — could you please share what ultimately fixed the issue? That would be very useful for others facing a similar problem.

Anonymous 2012-03-09 09:33

jeff compton wrote: And Steve, could you please share what ultimately fixed the issue? That would be very useful for others facing a similar problem. I’ll update you — I’ve been waiting for the Check Engine light to come back on before taking action. My wife reported that the car runs well under normal conditions. After adjusting the bend of the #3 spark plug so it sits directly over the electrode and clearing the P0303 code, no further check engine lights have appeared. Interestingly, this issue began after my wife took the vehicle in for a new battery. She initially reported idle problems and stalling. The shop diagnosed an IAC valve issue — which didn’t resolve it. Then they performed a full tune-up (wires, plugs, air filter) and replaced the fuel filter. Three days later, P0303 reappeared. I recently acquired the Haynes manual and learned that disconnecting the battery (for any reason) triggers a relearn process for idle control and emission trim settings — something I believe the shop didn’t know about. Last Sunday, I disconnected the battery, let it sit for one hour, then reconnected. After starting the engine, I allowed it to warm up fully, then turned on the AC at maximum for an additional minute. We took a 10-mile drive afterward. After that trip and the next day, the idle issue disappeared — and so far, no misfire codes have returned. Steve Pheasant Hollow Farm