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2002 Ford Taurus (OHV) P0316 Misfire with No Cylinder Identified & P1233 Fuel Issue - Diagnosis Guide

Model: 2002 Taurus (OHV) Fault Code: P0316 Posted: 2006-12-29 16:55

Hi everyone, I'm currently troubleshooting a persistent misfire issue on my 2002 Ford Taurus (OHV). The engine is throwing a generic P0316 code — indicating a random or multiple cylinder misfire — with no specific cylinder identified. Despite the vehicle not exhibiting obvious symptoms like loss of power or rough idle, I'm concerned about potential underlying issues. I've already checked the spark plugs on the odd-numbered cylinders and confirmed they are functioning properly. The injectors are also firing as expected. However, I haven-'t yet tested the even-numbered cylinders due to concerns about removing the intake plenum (plastic components only — not the intake manifold). Before pulling apart the engine, I'd like to know the most effective diagnostic steps to identify which cylinder is causing the misfire. Additionally, I recently cleaned the Mass Air Flow (MAF) sensor using brake cleaner to clear a previous fault code. While this helped reset some systems, it may have contributed to the current issue. I'm also curious about spark plug recommendations — my current plugs are around 5 months old and were replaced with Motorcraft AGSF32FM. I've heard conflicting advice on heat range selection. What's the best practice for this model year? Also, I checked the CKP (Crankshaft Position Sensor) and measured approximately 1.4VDC at connector KOnEOff, with ~2VAC output during cranking. Any insights into why a P0316 appears without a specific cylinder reference would be greatly appreciated. I've been told that the ECU compares crank and cam sensor signals to detect misfiring cylinders — is this accurate? My wife (primary driver) reported that the MIL initially blinked before settling into a constant light. After resetting via OBD2, it stayed on continuously. I’ve read that blinking indicates one type of fault while a steady light suggests another. I plan to let her drive it for a bit and monitor if any new codes appear. UPDATE: I recently detected a P1233 code — related to fuel system issues. This may have been triggered when I temporarily removed the fuel pressure cutoff switch in the trunk during engine cranking tests. After using an OBD-II scanner to clear the codes, no errors are currently showing. I'm now wondering whether simply resetting via OBD2 is sufficient, or if a full power-off reset (like disconnecting the negative battery) is required for proper code clearing. Thanks in advance for any advice — I want to avoid unnecessary engine disassembly until I have a clear path forward.

Related fault codes
P0316P1233
Comments (4)
Anonymous 2006-12-29 17:15

What age are your spark plugs? Age can significantly impact misfire diagnosis, especially on older vehicles like the 2002 Taurus.

Anonymous 2006-12-29 18:58

The plugs are about 5 months old. The car showed hesitation before and after installation — it ran smoothly afterward. I used Motorcraft AGSF32FM plugs, which aren't original. There's some confusion online regarding the ideal heat range for these engines. What would you recommend? Also, I measured 1.4VDC at CKP connector KOnEOff and ~2VAC during cranking.

Anonymous 2006-12-30 07:21

The best spark plugs are typically those recommended by the dealer's parts department — they're usually up to date with manufacturer specifications. Aftermarket brands may not reflect current heat range improvements. If you're using original-style plugs, consider replacing the ignition wires as well, especially since older Taurus models use traditional wire systems rather than coil-on-plug (COP) setups.

Anonymous 2006-12-30 10:03

Thanks Jeff. Can someone clarify why a P0316 appears without specifying a cylinder? I understand the ECU uses crank and cam sensor comparisons to detect misfiring, but is that accurate? My wife noted the MIL blinked initially then stayed on — does this indicate a specific type of fault? I'm planning to let her drive it more and see if any new codes appear. UPDATE: I found P1233, which relates to fuel system issues. This may have occurred when I removed the fuel pressure cutoff switch during testing. After clearing with an OBD-II scanner, no errors are present now — does this mean a full battery disconnect is needed for proper reset, or can OBD-II suffice?