2003 XLT 5.4 misfire after weeklong rest

[Plati]

My 2003 5.4 XLT 178K miles --- Normally, I drive it every day and no problem. Lately it sits all week while I drive the 2014. When I start it up on the weekend .. it runs rough (like a misfire) for the first few miles, then fine. I don't think all 8 cylinders are running. Doubt thats good for the engine, I can live with it but ... would prefer all 8 working ALL the time. Any suggestions how to diagnose? I used my bluetooth OBDII and TorqueLite and see no ECU codes. Filled it with NO ethanol 90 octane gas today to see if that would help, no good reason why - but I figured why not try it?

 

[Dewayne]

Gonna need a scan tool that can look at misfire data.

 

[Plati]

Gonna need a scan tool that can look at misfire data.

I've got the BAFX & Torque Lite ... is Scan Tool the Android software or the BAFX?

 

[Trainmaster]

There's a coil for each plug, and probably one of them is breaking down. Of course it can be a bad spark plug too if they've been in there 100,000 miles. Driving with a miss will ruin your catalytic converter pretty quickly, so find the offending coil and change it. Use a Motorcraft one - the ebay imports that are 10% of the price are junk.

If you don't have a tool to help find the offending cylinder, you can unplug the coils one at a time while the motor's missing. When you unplug one that doesn't make the miss worse, you found the offender. Old school stuff.

 

[1955moose]

Your Bafx is a obd2 scan tool. I believe your torque light is also. Surprising you didn't get a misfire code for one of your cylinders? Something like p351 thru p358. Be sure your obd port has got voltage, theirs a fuse for it. You might also want to do, or have done a fuel pressure test. Seen a lot of weak fuel pumps lately. Report back what you find.

Sent from my N9131 using Tapatalk

 

[Bain64]

Do the spark plugs have 178k on them?

 

[Plati]

Plugs got changed @99K. I also asked for new wires (didn't know about COP) but not sure what I got. The way I looked at the problem is that it still could be a plug, COP, injector, or anything ... Stuff can fail at any point so I wanted to diagnose it to what is failing. I need to learn more about using the OBD2 tool, I just looked at logged, pending codes, & historical codes and it said no ECU codes. I'm on the road all week so ill look at it again this weekend. I think I have to go into sensors or something to see misfire & I might as well pay for full Forscan or Torquepro or both vs trying to use free version.

 

[JExpedition07]

Well with the plugs being changed last at 99k I'd say even they are open game. Huh, hopefully it logs a code so you can tell what cylinder it is

 

[1955moose]

Electrical or lean misfires will always Trip a code, fuel pressure, and catalytic problems not so much. You can do this the parts changer way, which we never recommend or you can attack this like a journey level mechanic. Me I'm a cheapskate, and never like throwing parts at a vehicle willy nilly. Any problem in your primary/secondary ignition will show up by using scan tools proper. You might want to again check your power for diagnostic port for obd scanner You should be throwing some code. Stop by any parts/ repair shop, they'll scan codes for free. Your fuel pressure test, you'll have to pay someone, or buy/ rent a gauge to test yourself. You'll need to get back when you have time. All the other should a could a, are a waste of time.

Sent from my N9131 using Tapatalk

 

[Plati]

Bafx dongle is working, I can see lots of data .. Vacuum, rpms, etc. ... on my android. Must have power so that's not an issue.

With my luck it will run fine now that I am on the trail. Temporarily anyway