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

 

[Jarheadmatt]

Sometimes it takes a while for a code to appear. about 50 miles. In the mean time the ECM will adjust air and fuel to try and compensate for the lean/rich condition until it gives up and throws a code.

 

[1955moose]

Run a fuel pressure test as well. We need a baseline to determine if you may have a intermittent fuel issue. Should be above 35psi if lines are clear, and pump is ok.

Sent from my N9131 using Tapatalk

 

[Plati]

update .. 03 Expy sat for 6 days, started it this morning with BAFX in OBD port. Was running rough, let it run for a couple few minutes , no codes reported in Torque Lite, still rough. Drove it 2 miles and stopped/checked, now reported P03304 pending (not logged). Cleared it and drove another couple miles ... no codes and running smooth. P03304 is misfire on #4.

Most likely seems COP and/or plug. Heard a heater hose through there degrades ... making me especially suspect COP. 80K on plugs, good time to change them anyway.

Next steps unknown but I think it would be good to get in there , maybe replace hose, plugs, and COPS, and have a nice look see around area --- since I really like this puppy and would like to continue to drive her. Things like this usually get worse not better if not addressed.

On the other hand, I could just wait for it to get worse and do the work then.

 

[1955moose]

I'd change out plugs, coil boots, that one coil, and definitely that weeping hose. The bargain coil sets usually fail premature, is why I'd leave the other 7 coils alone. Let us know if this helps your stumble, rough idle situation.

Sent from my N9131 using Tapatalk

 

[Jarheadmatt]

I didnt attend to a misfire properly. Cost me almost $3K in catalytic converters. If emissions is important, take that into consideration.

 

[Plati]

Update. It rained a LOT and started misfiring in the morning even though I was driving daily. I dropped it off at my local trusted shop. They diagnosed the P0304 and replaced #4 COP & Plug. COP looked bad like at some point fluid got on it. Seems fine now, but time will tell. I had told them to do all 8 if they wanted but these guys didn't think it was required. We're trying to keep it running right but not put extra money in it because it could go to junkyard at any point.

Motorcraft parts --> FD503 Coil & AP103 Platinum Plug
Also got fuel filter $220.

Guy did say its best to fix a misfire ASAP dumps unburned gas into CAT and can ruin it. Definitely good to address it!

 

[1955moose]

That's what we've been preaching here for years. Fix any coolant leaks asap or they will sure as sugar fry that coil. I agree with your shop leave the other Ford coils alone, the aftermarket ones are trouble! And he's also right about destroying the cats. A rich mixture is suicide for them. Their very delicate inside. Your on right track for now.

Sent from my N9131 using Tapatalk

 

[Plati]

..... And he's also right about destroying the cats. A rich mixture is suicide for them. Their very delicate inside. Your on right track for now.

I have a connection to catalytic converters so I want to be nice to them. I worked at Corning Glass Erwin Ceramics plant around 1980. The plant was the first US manufacturer of catalytic converter substrates. They mixed up ceramic batch and extruded it through a die like play-doh then baked it in huge ovens. Revolutionized the auto emissions control and played a big part in clean air to breathe. Plant ran flat out and I was able to work double shifts any day I wanted for 2 years. Kept one for myself. Those tiny honeycomb channels get infused with a catalyst and have a lot of surface area.



Invention of the modern automotive catalytic converter