cyl. 5 missfire. help!

Do you have a true dual exhaust setup? Just wondering because you said exhaust was barely coming out drivers side tailpipe. Now if you don't have dual exhaust; then I would immediately suspect an exhaust leak somwhere.

Sounds like you may have a stuffed up injector on cylinder 5. It's not compensating like the rest when higher fuel demand is required. Have you had fuel injection cleaning done in a while? You may be due for it.

When you replaced the plugs, did you notice anything unusual about the plug in cyl. 5 such as unusual color or odor? Oil, coolant ...excessively black or chalky white? Any smoke from the exhaust?

How many miles on this stang?

If you would've messed up the timing, it would be noticeable on all cylinders, not just specifically missing on one. True duals, then it's definately an injector issue. Probably some deposits lodged in from that cylinder running rich ( for some reason) or it just happened to be the first one to get crapped up. Injector shouldn'tt need replacement. You just need a good injector cleaning done. There is no good DIY way to clean injectors. Even if you remove them and spray/soak the end of each injector in cleaning agents (which I tried once and learned..doh!), it won't do much good. The cleaning has to be run directly through the fuel lines and pass through the injector nozzles. You can either buy the small canister + fittings and compressor and then learn how do do it yourself (not hard but those canister kits are expensive and must be bought through high end tool companies like Matco Tools ..SnapOn etc)... or you can take it to a well known reliable shop and pay for an induction service.

And the timing should be fine. There are no adjustments needed as it's auto done by the PCM. You also can't adjust it unless you have either a special scan tool to re-program the timing settings or get an aftermarket coilpack/ignition that has adjustable timing, which would probably need a reprogram of the PCM.

I'm going to rule out cyl. head problems. An 03 with only 50K+ miles ..its highly unlikely for head gasket problems at such an early mileage. Ford worked out most of those issues with older models.

I have an idea of what it might be. Could possibly be the cam synchro out of sync with the crank sensor. You did replace it, now that I double checked, the synchro has to be put in sync with the crank sensor. And I think it takes a special tool for that.

Did you have the misfire before you replaced the cam sensor? dont make sense to misfire on only one cylinder for an out of sync issue. The short term fuel trim on bank 1 does definately indicate a rich condition on the drivers side. Although I dont understand what bank 3 and 4 could be. Odd that theres a 3 and 4.


Need to try something. You'll have to reset the PCM after this so..

Unplug the cam sensor and drive it around. See if any of the symptoms still occur. Youu will notice a slight throttle hesitation with the cam sensor unplugged but it should run fine without it. Don't leave it like this, just checking to verify if the cam is actually out of sync. If it runs better without it, then it's out of sync. I'll see if there is a way to avoid having to take it in to a dealer or shop to have it sync'd up.

If you had this problem before the syncro was replaced, chances are you mightve cleared some of it up with the seafoam. pull the sensor and test for several miles first.See what happens.

If your problem isnt fixed it might be the Ecu once it throws a code and keeps throwing it will try to compensate for the prob mine dide the same but it was a number 4 misfire and a new ecu fixed it