Ford Fiesta 2004 1.4 Manual - P0103 and P0304 Fault Codes: Misfire and TMAP Sensor Issues
My 2004 Ford Fiesta 1.4 manual, with 40,000 miles, is experiencing a very stuttering engine. The onboard diagnostics show fault code P0103 and a freeze frame indicating P0304 (cylinder 4 misfire). This vehicle is equipped with a TMAP sensor instead of a MAF sensor. I have already replaced the TMAP sensor, but the issue persists. Spark plugs and high-tension leads for cylinder 4 appear to be in good condition. A user suggested that the coil pack might be faulty—however, I'm uncertain whether the misfire is causing the P010 or if the MAF problem is triggering the misfire. Can anyone provide guidance on diagnosing this issue accurately?
There is a known Technical Service Bulletin (TSB) for certain Ford engines regarding a cracked intake runner, particularly near the vacuum distribution block adjacent to the brake booster hose. Check the integrity of the ignition system and fuel delivery specifically to cylinder 4. If these components are functioning properly and a misfire persists, inspect the intake runner for cracks in that area. Additionally, there is another TSB related to sticking valves causing P0304 codes on some Ford models. You may want to contact your dealer or consult official Ford TSBs for your specific vehicle model and year to verify if this applies. Regarding P0103, inspect the MAF sensor body for any obstructions or restrictions. Also check the signal wire for short circuits to 12 volts—this could indicate a faulty sensor, though further verification is required before confirming.