Misfire under light load
07-27-2011, 09:35 PM
#11
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I found a TSB related to 5.4 misfire but it says for 07 and 08 years. TSB 07-24-8 ENGINE MISFIRE DURING CRUISE WITH OR WITHOUT DTCS Publication Date: November 28, 2007 FORD: 2007-2008 Expedition, F-150, F-250 LINCOLN: 2007-2008 Mark LT, Navigator ISSUE: Some 2007- 2008 Expedition, Navigator, Mark LT, F-150 and F-250 vehicles equipped with a 5.4 3V engines may exhibit engine misfire during cruise, rough run, hesitation, buck jerk, with or without diagnostic trouble codes (DTCs). ACTION: Follow the Service Procedure steps to correct the condition. SERVICE PROCEDURE Use Motorcraft® Carburetor Tune-Up Cleaner to clean engine combustion system. Disconnect canister purge line from the intake manifold. Attach a vacuum line to the purge port. At hot engine idle, allow the engine to ingest about a 1/2 to 2/3 of a can of Motorcraft® Carburetor Tune-Up Cleaner. Use caution not to ingest too quickly due to potential hydro-lock issues. Read the entire label on the Motorcraft® Carburetor Tune-Up Cleaner. Shake the can well before using and make sure to use at room temperature. Shut the engine off and allow it to soak for one hour. Start engine, allow the engine to ingest the remainder of the Motorcraft® Carburetor Tune-Up Cleaner. Reconnect canister purge vacuum line. Cycle engine between idle and 2500 RPM for about 5 minutes. Inspect the spark plugs for abnormal fouling. Replace fouled spark plugs. Re-gap the spark plug to .035" (0.9 mm).
07-28-2011, 06:31 AM
#14
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To change the plugs including decarbonizing, read the spark plug sticky at the top of this forum as it has great information on this complete subject.
It still amazes me in how many parts are suggested to be changed for a post such as this. Spark plugs, COPS, injectors, cam phasers and cat converters. If your dart gun points at the spark plugs as the first part change and that does not correct it, I'd suggest getting it diagnosed by a qualified tech before changing anything else.
These forums are great for getting support, and all the suggested diagnosis would be valid parts that could be causing your problem, but when you read that "mine did the same thing, and I changed <enter your part here> and it now runs great" in two or more replies, it's time to have it looked at by a qualified tech.
Just my opinion in trying to save you money. You can keep tossing money into it by changing parts; sooner or later you will correct the fault, hopefully before you simply replace the engine!
It still amazes me in how many parts are suggested to be changed for a post such as this. Spark plugs, COPS, injectors, cam phasers and cat converters. If your dart gun points at the spark plugs as the first part change and that does not correct it, I'd suggest getting it diagnosed by a qualified tech before changing anything else.
These forums are great for getting support, and all the suggested diagnosis would be valid parts that could be causing your problem, but when you read that "mine did the same thing, and I changed <enter your part here> and it now runs great" in two or more replies, it's time to have it looked at by a qualified tech.
Just my opinion in trying to save you money. You can keep tossing money into it by changing parts; sooner or later you will correct the fault, hopefully before you simply replace the engine!
Last edited by Mod (Ret.); 07-28-2011 at 06:35 AM.
07-28-2011, 09:59 PM
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My experience with " Qualified Technitions" is they are more likely to throw parts at my truck and waist my money than I am. There is a proper way of trouble shooting any discrepancy and in my experience, a Tech will bypass all trouble shooting and throw parts, that the have had problems with, into my vehicle costing big bucks. The Forum is a wealth of knowledge and Know how that surpasses any "Tech's" knowledge. Sure there are guys that will tell you to pour a quart of transmission fluid down your intake to fix the problem but most of the information is quite helpful.
"If you build it, they will come"
"If you build it, they will come"
07-29-2011, 07:05 AM
#16
Moderator (Ret.)
My experience with " Qualified Technitions" is they are more likely to throw parts at my truck and waist my money than I am. There is a proper way of trouble shooting any discrepancy and in my experience, a Tech will bypass all trouble shooting and throw parts, that the have had problems with, into my vehicle costing big bucks. The Forum is a wealth of knowledge and Know how that surpasses any "Tech's" knowledge. Sure there are guys that will tell you to pour a quart of transmission fluid down your intake to fix the problem but most of the information is quite helpful.
"If you build it, they will come"
"If you build it, they will come"
I know many people that hold an ASE certified training degree, and bypassing diagnosis and tossing parts was in no way their method of training. My friends that have gone through this training and are now certified ASE technicians are proud of their knowledge, and are very good at troubleshooting and repairing. In no way do they "toss parts" to fix a problem. Rather this something I usually see happening here on these forums.
I'll agree that forums such as F150Forum are good places to get advice and help in resolving a fault, but when you receive several suggestions on a diagnosis to a problem, there comes a time when you stop "tossing parts" and get it repaired by a good ASE trained technician.
Hopefully you have better/other repair facilities with qualified techs in your area that you can use other than the ones you describe in your reply.
Last edited by Mod (Ret.); 07-29-2011 at 07:09 AM.
07-29-2011, 07:29 AM
#17
'08f150stx
X2 Bucko........I took certification training but have not worked in that field for awhile. I was very proud that I could diagnose problems, even without the use of diagnostic equipment. Now you MUST use that equipment. And yes, early on in your post it sounded like it was spark related. I would have gone plugs, if that did not fix it, I would have gone to an ase certified mechanic.
Good luck if you throw parts at it, I hope you hit it sooner rather than later.
My son, 26, throws money at problems. Ends up costing him more than going to a certified mechanic. And of course, he won't listen to Dad.
Look at what you might do and spend all the money for no fix;
Injectors, cats, O2 sensors, you already did cops, and there are more.
Good luck if you throw parts at it, I hope you hit it sooner rather than later.
My son, 26, throws money at problems. Ends up costing him more than going to a certified mechanic. And of course, he won't listen to Dad.
Look at what you might do and spend all the money for no fix;
Injectors, cats, O2 sensors, you already did cops, and there are more.
