2001 Ford Mustang Problems: 3 Known Issues

On the 2000-2001 Ford Mustang 4.6L SOHC V8, early 4.6L SOHC Mustang GT models used a composite intake manifold that is known to crack around the coolant crossover/thermostat area, causing sudden coolant loss and overheating. This was a widespread Ford modular V8 problem and appears repeatedly in owner reports and service literature. Owners typically report coolant smell, visible leaks at the front of the intake, steam, and rapid temperature rise.

On the 1996-2004 Ford Mustang, sN95 and New Edge Mustangs with the 4.6L modular V8 throw P1506 more often than the stock failure rate would suggest, and the reason is frequently something done to the intake side of the engine. The modular throttle body has a mechanical stop screw that sets how far the butterfly rests open at idle. The IAC needs a specific, small amount of bypass air to have authority in both directions; if the stop screw has been turned out to chase a lopey idle, or an aftermarket intake manifold or throttle body was fitted without resetting base idle, the plate itself passes more air than the PCM's minimum IAC command can offset. The PCM sees actual RPM sitting above target with the IAC already driven closed and stores P1506. The other half of the cases are genuine unmetered air. Aftermarket manifolds, cold air intake tubes, and repeatedly removed IAC gaskets all leave sealing surfaces that leak. A smoke test on these cars frequently shows air seeping around the IAC motor mounting flange itself or at the manifold-to-head gaskets. A PCV valve stuck open, or a PCV hose that has hardened and cracked at the elbow, does the same thing, as does the vacuum hose that runs from the back of the throttle body down toward the passenger wheel well. Owners report idle sitting at 1,000-1,200 RPM in park, RPM that wanders or surges, and the code returning shortly after each clear. What makes this pattern frustrating is that the usual shotgun sequence - clean the throttle body, clean the MAF, replace the IAC, replace the PCV - changes nothing, because none of those parts is the leak.

On the 2001-2004 Ford Mustang, manual-transmission New Edge performance models are well known for throwout bearing, clutch fork pivot, and front bearing retainer wear that causes chirping, squealing, or grinding noises when the clutch pedal is depressed or released. On 2003-2004 supercharged Cobras in particular, owners frequently report repeated throwout bearing failures and clutch engagement issues. If ignored, the problem can progress to poor clutch release, transmission input shaft wear, and more expensive clutch/transmission service.