Hi I am relatively new to this site and am reading about issues similar to mine. I have a 2006 Lincoln Mark LT that seems to have an intermittent misfire. The truck is not throwing any codes either. Any ideas out there?

 

I've moved your thread to the 2004 - 2008 F-150 forum. Although your truck is the Lincoln version, the two have the same engine so someone here should be able to help you out.

 

I'm not sure of all your symptoms and or maintenance history but I had a similar problem and it was a bad coil. These engines have a coil for each spark plug. Depending on mileage you may be best to change all 8. My mechanic was able to drive the vehicle with a laptop connected to it to determine which cylinder was misfiring. It's not a huge investment but its worth checking out. A good way to know if your problem is similar to mine is to follow this scenario. Find a long uphill grade. Let the vehicle shift into overdrive and as you climb the hill very gently try to accelerate without the truck downshifting. If its like mine you feel the misfire pretty regularly. Not sure of your tire size or gearing but 39-42 mph is the sweet spot for this test.

Good luck.

 

90% of all miss fires are due to a bad coil (COP).... figuring out which one is the problem. Some readers will do that without the code... sometimes you can play with the throttle and make it give you a code eventually....... or you can change out a couple coils and see if it goes away... If not, put the two removed coils back on in a couple other spots and eventually go thru till you get the right one changed out.

 

With a scan tool perform a cylinder contribution test a negative reading on a cylinder is your misfire. -15 seems few down to dead -30. From there could be coil, plug, fouled plug boots from antifreeze or water soak. Sometimes a injector. no drop in rpm from unplugging injectors or coils your own risk one at a time is another way without a scan tool

 

@babe69vw


I have an '04 5.4L 3v Triton. Having been through similar symptoms - I have done a LOT of work "hacking" the OBDII system trying to get (at least) a little smarter than the ECU on my truck. You mention that you have NO DTC. However, in addition to "freeze frame data" generated at the time a trouble code is stored, the ECU maintains a good bit of real time data relating to misfires.


If you have, or have access to, a scanner that will query specific or custom parameter ID's (such as the Troque Pro App), these PIDs might prove helpful. The following Table is information I have uncovered about HEX PID's from which the ECU will respond to a Mode 22 request and provide additional information the ECU has stored about the most recent Misfire incident. Disregard the comments in { braces } as they are hex or decimal readings from my spreadsheet for my own vehicle information.


Command Response Acronym PID Description Units comments
Cmd: 2216d3 response:6216D30A48 MFF RPM 16D3 Engine RPM at time of Misfire RPM {logs 4755, 5788 later}
Cmd: 2216d4 response:6216D411F4 MFF LOAD 16D4 Engine Load at time of Misfire % {logs 6888, 7888 later}
Cmd: 2216d5 response:6216D500 MFF VS 16D5 Vehicle Speed at time of Misfire km/h mph
Cmd: 2216d6 response:6216D638 MFF IAT 16D6 Intake Air Temp at the time of Misfire Degrees {logs 56 – 37 later}
Cmd: 2216d7 response:6216D70005 MFF SOAK 16D7 Engine-Off Soak Time at time of Misfire Minutes {logs 162}
Cmd: 2216d8 response:6216D8FF MFF RNTM 16D8 Engine Running Time at time of Misfire Minutes {logs 10 }
16d9 16D9 MFF EGR 16D9 EGR DFPE Sensor at time of Misfire Volts {logs "-"}


There are numerous factors that lead to misfires under the conditions cited by @srb1194 . Low RPMs (1100-1250 RPM), Light engine load (50-60%) presents maximum challange to the 5.4L Triton theory of operation. Requested VCT retard is at Max 60º+ retard, VCT Solenoids are at > 50% duty cycle, phaser oil pressure is at minimum due to the low RPM's, the Intake Manifold Swirl Control (IMRC) Valve is about 75%-80% closed to create maximum "swirl" in the intake air stream above the intake valve hoping to better atomize the fuel mixture richened by increased short term fuel trim, and ignition timing is retarted to about 3º BTDC (or 0º on first knock sensor indication). EVERYTHING has to work perfectly to avoid miss-firing!!!!


I do not agree that "90% of all miss-fires are due to a bad coil (COP)...." as @steve(ill) suggests. (That's an over simplivication) Plus, someone needs to explain to me what wears out or even deteriorates in an epoxy sealed COP constructed of two coils of wire wound around an iorn core!!!! I do agree that it needs to be clean and free of cracks, moisture, greasy-oily finger prints, and poor electircal connections from corrosion or high resistance connections. But I think 99% of all replaced COPS are needlessly replaced.


@Mohawkwoodman's comment are complete hygrolyphics to me and make no sense at all, but unplugging injectors or coils isn't going to tell you a damn thing about a random misfire under light load at 45 - 55 mph. If you suspect a coil, invest $10.00 in an AMPRO High Energy Spark Tester from Amazon ( ) and save all that money for COP's.


Additional thoughts on the subject of random misfires that might be helpful are included in the following two posts.
5.4L 3V Spark Plugs Engine Build Dates before 10/09/07 - Page 86 - Ford F150 Forum - Community of Ford Truck Fans
5.4L 3V Spark Plugs Engine Build Dates before 10/09/07 - Page 86 - Ford F150 Forum - Community of Ford Truck Fans


As you can tell from the above posts, I suggest you start with a good, clean, well executed spark plug replacement. And make sure to clean COP connections / streech out springs and replace (or at least clean Boots) and use dielectric grease on both the Boot and the primary connector. REPLACE any of the plastic primary connectors that have broken latches.


Sorry for the winded response, but I think you were being mislead.


Good Luck

 

I wrote a way to diagnose misfires. The cylinder contribution test is where i start. It shows you which cylinder is having misfire problems. You have to at least id that to narrow things down.
Babe69vw have you tried changing fuel stations?