2006 FORD F-150 5.4L 3V Triton Multiple misfires

I have a 2006 Ford F-150 XLT 4X4 5.4L 3V TRITON with 128152 miles. It had a misfire under sever load. I ran an Actron diagnostic tool on it and it diagnosed cylinder 8 misfire P0308. I decided because of its miles it was time for a tune up. I replaced all 8 spark plugs with motorcraft plugs and all 8 coils with some cheap amazon coils. Afterwards I started the engine and had multiple missfires P0303, P0304, P0305, P0307, P0308. I assumed after testing the voltage going to each coil and to each injector that maybe I purchased bad coils and plugs, so I replaced all 8 coils this time Accell coils and Motorcraft platnum plugs. still had a multiple misfires at an idles and when driven it seemed as if it was only firing on four cylinders. My freind connected his Verus up to the truck and told me that No. 8 and 4 was misfiring. I replaced No.4 and No. 8 connectors and injectors and swapped the coils around to coils I knew was firing correctly, Still No. 8 misfire. I replaced both VCT "Variable Cam Timing" Solenoids both CPS "Cam Positioning Sensors", fuel filter added Seafoam to the fuel. I flushed the motor which the oil was not gunked up. The valves on top of the head looked clean when i removed the grommets that go around the VCT's. I ran Seafoam direct spray injector cleaner for five plus minutes and shut the vehicle off to let it bake. Drove it down the road and still no change in No. 8. When the key is on the on position my amp meter shows 12.4 amps on both wires of the coil on plug on cylinder 8 when running it shows 14.4 amps. what are your suggestions? I replaced the PCM with a new one with all the updates, and the problem still exists. I did however have other codes for primary and secondary circuits A-H throughout this whole process. I have not tried a back pressure test on my catalytic converters yet but my temperatures on the pair of them driver side and passenger side cats are running at the same temps at an idle around 867-870f, as I increase throttle the temperatures of each one increase within a degree or two of each other. Any ideas or pointers of what i can trouble shoot next?

have you checked compression? also what I do on ford since there misfire counter sucks and I have a misfire at idle ill unplug all coils one at time and check cylinder contribution. also does it misfire under idle? I think I read it right. maybe the egr valve is having issues if the miss goes away under load

also did you gap the plugs to spec?

The plugs have the solid ground strap. Yes it misses at idle and severe miss under load. I have yet perform a compression test but that is my next step. I have unplugged each coil one at a time while running to see if there is a noticeable change in idle number 7 and 8 does not see to make a difference unplugged as well as number 3. The triton engine does not have an EGR due to cam phasers and VCT solenoids. I appreciate your input though and will be checking the compression soon, just waiting for the gauge I ordered to arrive.

did it do it before the new coils/plugs? kkep us posted

quick question did you put a noid light in place of the coil and see if it flashes? im trying to figure what the next move is

Yes it had a slight miss prior to tune up only under severe load, I mean throttle to the floor in gear. Also it had the shudder that these tritons are know for from misfire due to coil or plugs, that is why i decided to give it a complete tune up. Like i said not only did change the plugs once but i changed them twice and have rotated the plugs as well as the coils to see if it follows the plug or the coil, it made no difference. I also used a mechanics stethoscope down the valve covers and heard no noises like valve springs. the phasers are relatively quiet no excess noises and ran the stethoscope down the front timing chain cover and no noises. I thought maybe i had a stuck valve or valves on cylinder 8 but Im not sure how to trouble shoot or diagnose it means how I have no valve noises.

yes, I ran a noid light on the coils and on the injectors and it shows spark and pulsation for the injectors.

I really appreciate all of you taking time to read and respond to this problem. Any pointers are appreciated. Thank all of you and Happy Thanksgiving!!

Hey sir, Happy Thanksgiving!

I'm curious about the readings you took at the #8 coil connector:

When the key is on the on position my amp meter shows 12.4 amps on both wires of the coil on plug on cylinder 8 when running it shows 14.4 amps.

Are you sure you meant amps, and not volts? 'Cause those readings suggest a dead short in the circuit. A voltage reading of the same value would make sense with the engine stopped and running. Not trying to nitpick, just want to be clear

So, this thing had the typical 'fishbite' ignition misfire before, and definitely runs worse now? Pretty sure the coil connectors aren't long enough to mix up between cylinders... You've moved coils and plugs... Noid light says control is there... Power balance test backs up the code... Love the testing you've done so far! All stuff I'd do in the same situation.

I see that you have an Actron scanner, does it have access to scan data? Even good ol' Global data will work. Mostly I'm interested in the fuel trims. This can give us an insight into how the engine is breathing. Speaking of, you could remove the upstream O2 sensors to check for a plugged cat. BUT, that's a huge pain on these trucks, so I don't want to suggest that yet

A quick relative compression check would be easy to do. No scope required, just floor the gas pedal, crank the engine, and listen to the cranking cadence. If there's an low compression problem, then you'll hear the engine 'skip' the low cylinder as it cranks. FYI, this test doesn't completely rule out mechanical problems, but it's a good direction test. Here's an example:

well what you could do is put the original coils back in and if it runs better you would know theres a problem with the new coils. and not with the truck simple and cheap that is if you kept them though

garypuppet1 wrote: Yes it had a slight miss prior to tune up only under severe load, I mean throttle to the floor in gear. Also it had the shudder that these tritons are know for from misfire due to coil or plugs, that is why i decided to give it a complete tune up. Like i said not only did change the plugs once but i changed them twice and have rotated the plugs as well as the coils to see if it follows the plug or the coil, it made no difference. I also used a mechanics stethoscope down the valve covers and heard no noises like valve springs. the phasers are relatively quiet no excess noises and ran the stethoscope down the front timing chain cover and no noises. I thought maybe i had a stuck valve or valves on cylinder 8 but Im not sure how to trouble shoot or diagnose it means how I have no valve noises.

If you're concerned about a sticking valve, it would show itself with a vacuum gauge. Even with a lean or ignition miss, a vacuum gauge would have a steady reading. A sticking valve would be indicated by a steady ticking of the gauge.

Also, when I first got my Navigator, I went batty looking for the cause of a wot skip. It felt just like when a Ford cop was going bad, but only under heavy acceleration, like when passing on the highway. Long story short, it had a junk tire, so I replaced it with one of the correct size, but that was worn considerably less than the other 3.
There is no 2hi mode on the transfer case, only A4WD (automatic four wheel drive). It didn't like that one nice tire while it was trying to split torque between the front and rear axles and felt just like a misfire.

I meant amps not volts, nice catch. The Actron scanner data is as follows:
ABS LOAD(%) 16.9
ABS TPS B(%) 20.0
ABSLT TPS (%) 13.7
ACC POSS D(%) 19.6
ACC POS E (%) 29.8
ACC POS F (%) 19.2
BARO PRS ("HG) 30.4 , I live in Ohio, i think this should be higher
CALC LOAD (%) 20.8
CAT TEMP11 (F) 895
CAT TEMP21 (F) 894
CLR DIST (mi) 0
CLR TRPS 0
CMD EQ RAT 0.999
COOLANT (F) 153
ENG RUN (m:s) 04:39
ENG SPEED (RPM) 674
EVAP PURGE (%) 15.3
EVAP VP (H2O) -0.034
FUEL LEVEL (%) 48.2
FUEL SYS 1 CLSD
FUEL SYS 2 N/A
IAT (F) 34
IGN ADV (o) 10.0
LT FTRM1 (%) 0.8
LT FTRM2 (%) 3.1
MAF (LB/M) 0.82
MIL DIST (mi) 0
MIL STATUS OFF
O2S11 (V) 0.100
O2S12 (V) 0.395
O2S21 (V) 0.050
O2S22 (V) 0.785
OBD2 STAT CA
OUT TEMP (F) 12
REL FRP (PSI) 39.23
REL TPS (%) 2.0
ST FTRM11 (%) 2.3
ST FTRM21 (%) 5.5
ST FTRM1 (%) -2.3
ST FTRM2 (%) -0.8
THROT CMD (%) 3.1
VEH SPEED (MPH) 0
VPWR (V) 14.653

Man, it's cold up there in Ohio, huh? :lol:

Fuel pressure looks good, and the trims are surprisingly reasonable for having two misfires. I was honestly hoping to see higher trims on bank two, suggesting a lack of spark or fuel A restricted injector is still on the table, but you'd have to move it to another cylinder to confirm.

Any luck with the relative compression test? I also like Noah's idea of the vacuum gauge. I saw that you listened to the valve covers, but I know that broken valve springs are common-ish on this engine, so it's still on my mind. We can also go further into mechanical stuff once you get the compression gauge, of course.

Okay, this is what my Actron test shows for misfires:

Misfire count cylinder 1 : 7
Misfire count cylinder 2: 6
Misfire count cylinder 3: 0
Misfire count cylinder 4: 0
Misfire count cylinder 5: 5
Misfire count cylinder 6: 1
Misfire count cylinder 7: 194
Misfire count cylinder 8: 2131

These tests was after 5 minutes of run time on engine. I did notice they do not exceed these values even with longer run time. The highest cylinder 7 ever registers is 197, I am guessing for cylinder 8 that must be as high as it goes before reset.

I typically do not use mechanics to fix my problems because I have been working on cars for 25 years, and this Ford has me stumped I am really considering after four weeks of working on it. I will definitely be purchasing a Snap-on Verus in the real near future. When I first performed the tune up it sat and idled for twenty minutes with out a miss noticeable and when I backed it out of my driveway and started up the street I went maybe 100ft and just stomped the gas to see if it would respond faster and it just fell on its face and had this problem ever since.

well let us know what the compression is when you get time

I'm wondering if this is a separate failure from the issue you were addressing with the tune-up, Gary Any other work performed at the same time?

Thinking about an injector problem, maybe you could pull the #8 plug again and see if it's wet with fuel? This would at least tell us that the injector is spraying something.

I have pulled the plugs and they was wet, I also changed the #4 and #8 injector. i have tested the injectors and they are working properly I used a noid light and they pulsated as they should. I also ran noid lights on the coils and they are firing as they should. I have already changed the plugs and that did not make a difference, i even rotated the plugs from cylinder to cylinder to see if the problem follows it. the trouble was still cylinder 8 and cylinder 7. I am convinced now it is either a compression issue, valve issue, or catalytic converters. Tomorrow I will receive my compression gauge in the mail and will perform a compression test on all 8 cylinders and if that results no issues, I will remove both cats from the headers. The misfire before the tuneup was only noticeable under heavy acceleration, like extreme passing situations. I did save all my old parts and have tried to reuse them to see if that took it back to the before results and it did not. I also plugged an old coil into each coil connector inserted a spark plug into the coil and started the engine it has spark on each cylinder, the arc jumped about 6" to ground on each cylinder.