I've got an 06 F-150 XLT with the 5.4 V8. The truck seams to run perfect unless I stomp on it to pass a car or accelerate fast. The engine starts spitting and wont rev up, as soon as I let off the gas a little it seams to take off and run good but if I hold my foot on the floor it just sounds like popcorn and just sputters and wont rev. It only seams to do it when I stomp on it and it down shifts, if I accelerate somewhat slowly and allow it to rev up it sounds perfect. Also the check engine light comes on occasionally and then goes back off. Unless the truck is doing this sputtering, then the check engine light flashes and usually flashes for several miles after, then either goes off or stays on steady. I had it scanned and they didn't give me a straight answer as to what the code was, the mechanic said the catalytic converter says its not hot enough. I guess I need to take it somewhere else and get it scanned but there are very few places within 40 miles of me..

I tried running a few different types of fuel injector cleaner through it first, then changed the fuel filter, then took it in and the mechanic just kinda ignored the light and reset it for me but didn't fix anything. I've run several tanks of good gas through it to make sure its not bad gas and that dosn't seam to be the case. It reminds me of the throttle override system on my old yamaha banshees, they would act up if the throttle cable wasn't adjusted perfectly and the motor would spit, sputter and not run until it was within adjustment... I just don't know enough about these motors to work on it and find the problem myself, and Im tooo0oooo busy working 2 jobs... I just wish I could figure this out, I think its probably something simple...

 

shanksyamaha,
I am not a professional mech but "popcorn" That sounds kind of like what a few others on the site have diagnosed as a bad cat. converter due to a fuel injector getting stuck open and dumping fuel, which can cause cat damage. This is a known problem with this engine. I am also thinking fuel filter or plugs. There is a wealth of knowledge in the membership pool here. Getting the codes scanned from a local auto parts store would be key to diagnosing. Also, how many miles on engine, what the vehical history if known, any recent work. Fuel filter would be where I would start. It only takes a few minutes to replace and while your at the parts store you can get your codes read for free. You want the actual code not just the description for example code P402. If you do the fuel filter DIY don't forget the tool cost around 5 bucks. Again I am a novice but this is my 2 cents. Good Luck

Shawn

 

You need a set of plugs. Change them ASAP because the cats dont tolerate misfires very long.

 

Thanks for the reply Shawn... I did the fuel filter allready and it looked original but didn't seam to have any resistance when I blew threw it. It sure didn't hurt to replace it but didn't help the issue.

I was wondering about the cat. myself. The first mechanic who looked at it said he thought it might be the cat but said to replace the fuel filter first since its a cheap thing to try and could never hurt to replace. The truck was owned by a family friend who passed away a year ago and his wife drove it for a year after that and I bought it from her. It was never abused and I don't think they ever knew it had a problem because I doubt they ever stomped it to the floor to pass anyone. It was only driven 55 at the max. Its got 82k on it now, I bought it with 78k on it and the problem has been there since I picked it up.

Is there any easy or relatively cheap way around replacing the cat?? I don't know what one costs for this truck but I know they arn't cheap and I just put $800 in brake parts and odds and ends in this truck....


Thanks guys!!

 

do you think thats the problem??? The truck runs perfect until I stomp it to the floor and it down shifts and hits high R's... It never acts up unitl then... Do you think its possible that the cat is allready bad?? Or should I just do the plugs and then see if that helps?? How hard are the plugs to change on these V8's?? I had a hell of a time with my old V10

 

If you beat on the convertor with a rubber mallet and it rattles inside its bad. Just make sure it is internal not a hanger rattling etc. Ran into the exact same thing on a suburban one time. The bigger chunks can plug up the out let causing it have a misfire under hard acceleration. If it does have a misfire caused by a plug or injector and the convertor is bad you must address this or the new cat will be damaged as well.

 

The plugs can be a chore, be sure to have a removal tool such as the Lisle 65600 or similar. I get the engine warm, soak the plugs in motorcraft carb cleaner (the thick stuff in the metal can not aerosol), and remove with a 3/8 impact. Have not broke one with this method yet. This site is a wealth of knowledge about these sparkplugs so look around see what you think will work best for you. Just dont be surprised if you break a few no matter what method you use.

 

It's the plugs. I work on these things for a living and the gaps I have seen on some of the plugs were so large you could drive a truck through. Put in Motorcraft SP515 plugs and be done with it. Get the Lisle tool just in case any break, change the plugs when the engine is HOT, take out the old plugs with a strong air ratchet or 3/8 impact, and apply anti seize to the area below the threads. I take the PCM out of the way too. Good luck

 

Well good for you. I do too and you are more than likely right but to say 100% without looking over a vehicle or even knowing the mileage that its is sparkplugs and only sparkplugs causing the problem is not something I would say. Seat of the pants diagnosis can and will come back to bite you in the ***. Then you get to sit in the owners office with him and a customer who is madder than a hornet and explain yourself when another dealer finishes the repair and fill them full of bs on how it probably never even needed the parts you put on. Ok im getting off my soapbox now! It has been one of those weeks lol

 

Well I guess I'll try and change the plugs first since its much cheaper than the cat. I'll smack it a couple times with a rubber mallet and see if it rattles also so I can get an idea if it sounds bad..

I have never heard of the Lisle 65600 tool. Is that something I can pick up at any auto parts store or is it a ford thing??? I was gunna ask what plugs I should get, Im sure everyone has their favorite brand but if the motorcraft sp515 is the proper plug for this truck and works well then thats what I'll get....

Thanks for all the help guys, I've been looking around the site at old posts on changing plugs, tons of info just takes a while to sort through it all...

 

I know that Oreilly sells lisle tools but I would think any parts store could get them. They are also available online.

 

Well the lisle tool is $100, I might just take the $100 and have it done for me, Im just so short on time right now with too many projects going.. The sp515 plugs are $25 each so that alone will be over $200, I might go with something a little cheaper on the plugs too, I don't want junk but seams like $25 is alot....

It was also mentioned that I may have a stuck fuel injector that could ruin the cat. How would I know if I do?? and need one fixed??

 

The spark plugs and Lisle removal tool (65600) can be had real reasonable from Rock Auto.com.

 

CB maybe you should re-read the OP. Im not getting into a pissing contest here but what he is describing is misfire under heavy load. A clogged cat wont cause that. Sometimes a "seat of the pants" diagnosis is the best one. The flashing CEL is a dead giveaway of a misfire. The PCM is trying to tell you the cats are at risk of damage.

He did say the mileage and 82K is prime time for worn out 3v plugs. I have seen some with only 60K have a 3/16" gap.

 

Only a couple of things usually cause misfire; fuel system problems or ignition problems. Most of the time it's an ignition problem. With 80K + miles on the clock, I would start by changing the plugs and COP boots. I waited untill the recommended 100K tuneup schedule recommended by Ford on 2 vehicles and I can honestly say I'll never run more than 60-70K miles on a platinum spark plug again. The gap was too wide on all plugs from both cars. If the problem is still present, run a code scan to direct you to the right area. These trucks are known to have fuel pump module problems as well. But that usually give a little different symptoms like cause the engine to quit when warm and a P0191 code.