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

my prediction is a headgasket problem. with 2 cylinders next to each other having issues.... hope im wrong!!

And to answer your question of any other work done during the tune up, nope just a tune up. Two weeks before tune up COP on #5 failed so I replaced it. And the same day on my way to work my alternator went out so I replaced it on the job site and the cop. I replaced the drivers fuel module 13 months ago because it failed on my way to work. This truck cant seem to break down on my way home. LOL! Here is alist of the known problem with the truck I dont believe it has anything to do with my current problem but hell you never know.
1.) ABS light is on either one of the front wheel bearing sensors are bad or a short in one of the wires, I replaced the center rear ABS switch and tested wiring all is good.
2.) Heater core is going out. blows moisture on inside of windshield on passenger side. Never over heats does not use any antifreeze or water. I am not ready to tackle that project as of yet its been rather cold here in the evening when I get home and I believe this will take me a good 6 hours.
3.) Rear main seal is starting to show a little oil, but Im a die hard ford guy and I know they all do this at about 100,000 miles so not rush. Dont use oil between changes.
4.) Header is leaking on passenger side at outlet flange, Getting new exhaust once i figure the problem I have now.

Yes, I hope your not right. I have had that thought myself.

Ok guys I ran a compression test I have between 160 and 180 on each cylinder they all register the same the gauge bounces between 160 and 180. Sorry it took so long to respond just been working.

I took the exhaust off at the heades and notice that all cylinder show misfires but negative misfires, cylinder number 8 shows single digit misfires now as low as 1 but like I say they all show negative misfires in the single digits. I am starting to think it is my catalytic converters. I am call and price exhaust shops tomorrow and see what it will cost to have new exhaust installed from the headers back with new cats and mufflers. I will keep you posted. Any other things I should look at in the mean time? Let me know. Thanks

garypuppet1 wrote: Ok guys I ran a compression test I have between 160 and 180 on each cylinder they all register the same the gauge bounces between 160 and 180. Sorry it took so long to respond just been working.

No problem, thanks for getting back to us! Glad to hear base compression is good, nothing catastrophic. If you have the opportunity, it might be worth doing a running compression test on #8, and compare it to another cylinder on the other bank. This will help rule out stuff like worn cam lobes and broken valve springs.

I still don't think you have a catalyst problem, as the fuel trims you posted were pretty even bank-to-bank, but I could be wrong. Maybe do a backpressure check? Before you spend a bunch o' money at the exhaust shop.

How do I perform a backpressure test? also how do I perform a running compression test? At this point any test I can perform that would save me some money would be definitely be appreciated.

garypuppet1 wrote: How do I perform a backpressure test? also how do I perform a running compression test? At this point any test I can perform that would save me some money would be definitely be appreciated.

Since your 5.4L doesn't use an EGR valve, or have a DPFE sensor, your only choice for backpressure is to remove the upstream O2. Well, you could also drill a hole ahead of the catalyst, but that's not a very good option IMO.

Once you have the O2 out, use a backpressure gauge, or a regular vacuum gauge. The only real difference between the two is that the backpressure gauge set will come with an adapter to screw into the O2 outlet, for easier testing. Try renting one from the local parts store if possible? Check this video for more info:



Running compression involves having the gauge installed in the cylinder with the engine running (obviously), with the Schrader valve removed. This ends up being a good measure of how the cylinder is breathing. Generally, the reading you'll see is 1/2 to 1/3 of static compression, so somewhere around 60-85 PSI.

It doesn't have to be inside that range, necessarily, that's just the rule of thumb. Really, I'd just be interested to see how #8 compares to other known good cylinders. If all is mechanically well, then they SHOULD be nearly identical.

what is the engine vacuum? is the needle steady? bouncy? you can also check for a cat problem with a vacuum gauge.

I have not run a vacuum as of yet. I will not be able to perform test on it until this weekend. I have a question could this all be a cause of bad knock sensors? I read they can cause a late detonation in a cylinder by advancing or retarding the cam. How can trouble shoot them I know they are under the intake manifold, is there any test I can perform to rule the possibility of that out?

Cheryl, where is the best place to run a vacuum test, should the needle be steady? Do i perform it just at engine idle? How can I test the cat with the same gauge? Sorry at this point my funds are starting to run low with the holiday coming uo I have to try and perform as many tests as I can with as little specialty tools as possible.

This isn't a ScannerDanner video, but does a very good job of explaining how to use a vacuum gauge and what it's telling you.


This ScannerDanner video shows one method of testing for a restricted exhausting using a compund vacuum/pressure gauge.
The alternative method is to connect the vacuum gauge to a manifold vacuum source. (Thats below the throttle, as opposed to ported vacuum, which is in front of the throttle plate.)
You raise the engine to 3000 rpm. A vacuum decay, or steady reduction in vacuum at 3000 rpms indicates a problem with the engines ability pump air, presumably due to a restriction in the exhaust.

I am sorry its been so long I can not get mother nature to work with me. I ran a vacuum test on the truck while running and the needle is at 17.5ish and does not bobble it stay in place. I removed both cats and installed straight pipe and it has made no difference. So now i guess I am back to an ignition problem. any thing I should look for. Next does anyone have the diagram of the coil wires to the PCM so i can test it at the PCM, also what should the voltahe be at the PCM for each control wire to the coils running or not running? Thanks I really appreciate it.

Ok folks, Again with my boring f-150. What all causes a cylinder to misfire like 9 out of ten times?

I tested the coil on plug connector 1 side is 0.00 and the other is 14.2, if i test a little higher up the connector pig tail i have 14.2 on both wires when running. I unplugged the injector connector and plugged in an old injector and it click when it is suppose to open. So i hooked it back to the new injector while the truck is running and that injector along wit the other 7 click as they are all operating normal. I removed the coil while the truck was running and replaced it with another coil fastened it down and re-connected the connector and still the same problem. Like I say a vacuum gauge while idling stay at 17.5 and does not move the cylinder tries to fire but misses numerous time and then stumbles and continues to miss.

Here is an up date of the testing and work done, I have performed compression on cylinders 8-5 No.- 8 = 177lbs, No.-7 =180lbs, No. 6 = 180lbs, No. 5 = 180. I ran a vacuum Gauge at idle (700 rpm) I have 25 lbs vacuum holds steady "no bobbling in the needle", and it only drops 1.5 -2 at each 1000 rpm all the way up to 5000rpm than rev limiter kicks in. still consistently holds with no bobbling. when I fast snap the accelerator it drops to about 5lbs and then goes up to 29-30lbs and returns to 25lbs vacuum. I removed the valve covers and inspected for worn cam lobes and see no problem with cam or followers or lash adjusters. Valve springs had no noticeable cracks or breaks. I started the engine with valve cover off and watched each exhaust and intake valve spring, follower, and lash adjuster and nothing visually looked any different with the same amount of movement "atleast to the naked eye". Any thoughts suggestions on where I should go from here, testing, repair, ect... I also checked for a worn cam phaser and chain slack. The chain is tight and the phaser was 100% quiet while running with the valve cover off. Truck ran for about 15 to 20 minutes with no valve cover and slung out 3-4 quarts of oil, which im sure my wife just loved seeing on the drive way.

garypuppet1 wrote: . The chain is tight and the phaser was 100% quiet while running with the valve cover off. Truck ran for about 15 to 20 minutes with no valve cover and slung out 3-4 quarts of oil, which im sure my wife just loved seeing on the drive way.

Lol! I was just doing that a Subaru!

I just reread this saga from start to finish, quite an epic.

All the testing consistently shows that there is control of the injector and ignition coil at #8.

You've got strong steady vacuum at idle, which is a good sign for the valve train. (Some earlier posts reported 17.5 lbs, but the latest is 25 at idle. Did something change here?)

Static compression also reinforces the sealing of #8

I'm wondering about a head gasket failure at this point like Cheryl had mentioned earlier.
You said the plugs were wet when you pulled them at one point, are you certain it was with fuel and not coolant?
I'm not criticizing you, just trying to gather all the info can without being there.

I think it may be wise to pull the fuel rails and wire the injectors to the rail so that the pressure doesn't blow them out and put it over some cardboard and do a cranking evaluation of the injectors to see what the spray pattern looks like just because there clicking normal doesn't mean there not plugged it is less common on these vehicles with stainless lines but it can happen. If you don't notice anything off about the spray pattern then rotate those cylinders injector to a different position just to be sure it does not change. What are your codes now do you still have circuit codes or just missfires codes? Circuit codes will be set if you swap coils while engine is running so you may need to clear it and run it again . I would not tear into throwing more parts at this thing unless you can verify there bad it sounds like you have a small fortune in parts already not to mention countless hours! At 1 point you mentioned that coil wire dropped to 8.xx amps while running I assume you meant volts which wires were these readings taken from?

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The first vacuum test I ran was inconclusive because i didnt have a clamp on the hose of the vacuum gauge. When i repeated the test with the hose clamped is when i had the more accurate readings. Yes i am certain I have just fuel on the #8 plug not any antifreeze or coolant.

At this point I have the intake manifold and fuel rail removed from the truck. I did this so I could inspect the wiring harness behind the manifold against the fire wall. No problem found in that wiring harness. but Im currently waiting on parts I ordered before i put it back together I am replacing both knok sensors and the head cylinder temperature sensors and of course the intake gaskets. I have been getting consistent reading in the wiring to the coils and to the injectors and have been comparing them to the numbers that the ford tech website say I should be reading. same with at the VCT's and at the cam positioning sensors. I have probed every pin in the ECM and checked them against the ford tech sites specs and have not had any discrepencies.