pcdtmurray

I have a 07 5.4 that was mis-firing when engine was under load (just before transmission would downshift). there were no codes - had 90K at the time and the problem was getting more frequent. Had the plugs changed and the problem was solved. Now at 104K and the issue is starting to re-appear. No engine codes again - I'm thinking plug wires. Any advise would be appreciated.

nrivera04

There are no plug wires. Just individual coil packs. Are the coils new with the plugs? If not, Were the boots changed with the plugs? It's possible you have bad pack that's not misfiring enough to throw a code.

Other things may be a bad plug or wiring short to the coil.

bbrad1775

I have the same problem. New sp 515's solved it for a bit but now it's back. Changed boots but it didn't help. I do have the torque app with Bluetooth OBD2 reader and can see the misfires but I dont know how to set it to show which cylinder. Anyone know how to set it up so it does?

Summers22

iTrader: (2)

I have had good results replacing the boots and springs and before I do that I clean the copper contact in the nipple of the coil using paper type fingernail files cut in half length then again width wise. Use one section per coil to get all that junk off the copper tab.

F150Torqued

On the "MAIN" app screen, rotate the icons clockwise around the gauge and select "Test Results", the icon with red/green/gold graph bars. Torque Pro reads Mode 06 data and interprets Misfire Test data for you. It gives you misfire counts on each cylinder over the last 10 drive cycles. I think THAT is what you are looking for.


As it so happens - The OBDII system on our 5.4L trucks does not present dynamic misfires / by cylinder on live OBD Data. Therefore the individual cylinder misfire does NOT work on OUR TRUCKS. TOTAL misfires (across all cylinders) are available from PID # 1616, so if you are familiar with ADDING CUSTOM PIDS you can 'create' a custom gauge. But the PCM is keeps up with individual cylinder misfires and reports it in response to a Mode 06 (test) query which is supported in the Troque Pro App. The Mode 6 data is 'cryptic' hexadecimal data - and largely confusing unless you speak "HEX" - which most of us don't. The following table shows the TEST Number, completion codes, and description, and conversion formula for the Misfire Test. Compare your Torque Pro "Test Results" to it by Test Number and Completion Code.


There are lots of OTHER OBDII tests in addition to Misfires. So something important to understand about the results is - FOR THE MOST PART - it is "instantaneous" readings from sensors - such as O2 sensors/EVAP system and so forth - right THEN and THERE. Those results are performed instantaneously, so one shot at it might produce a questionable reading - that might not persist long enough to set a DTC. So do not get too alarmed. Just put it in perspective for troubleshooting.


If you want to ADD a "Total Misfires" gauge - go to Settings > Manage extra PIDs/Sensors > Add custom PID > OK, then input Mode and PID > "221616", Long Name > "Total Number of Misfires", > Short Name > "MFTOT", Minimum value > "0", Maximum value > "1000" (or whatever), Scale factor > "x1", Unit type "Cnt", Equation > "(A*256)+B", Header > blank, diagnostic start & stop blank - all without the quotations. Then go add whatever type gauge you want to display it (I use a digital numeric gauge).

pcdtmurray

Thanks all, I checked the bill from the plug replacement and the boots were not listed so that sounds like the logical next step. I'll post results when I have them.

F150Torqued

@pcdtmurray


May I suggest a possible good read for you. I struggled with low rpm light load misfires on my 5.4 for a long time before coming up with a theory. You might consider if it is applicable. http://www.ford-trucks.com/forums/11...l#post15819897

pcdtmurray

quick question - I took one of the coils off but could not get the spring out of the coil. I pulled to the point of deforming the spring and decided to stop - the spring was in excellent condition so I'm thinking that (boots & springs) is not the issue. any suggestions on how to get the spring out of the coil?

Summers22

iTrader: (2)

Yes, twist it in the direction of the springs angle toward the coil. I would say that is an issue, not a relief.......I have never had a single problem taking the springs off. Those boot end have micro-cracks that cause the spark to jump or leave the boot out of the side instead of the ends, so less spark is making it to the plug, causing a mis-fire. Should only cost less than $40 to do all 8.

techrep

iTrader: (1)

So many people replace the plug and don't replace what feeds the plugs..