My 2004 F150 5.4L V8 bogs down RANDOMLY when the throttle is pushed lightly to moderately. I have to push the throttle past a certain point to clear it up and make the engine pick up speed. It has been doing this since new but has gotten progressively worse over time but has been the same for the last couple years. It has 155,000 miles. The Ford dealer has no idea what the problem is. No codes show and they have ridden with me with the computor hooked up but it shows no codes when the engine bogs. They installed a new mass air flow sensor. Exhaust back pressure is normal. All seals around air intake are in place. I've got over $500 in this last attempt to have the Ford dealer fix the problem. It also has the classic surging when at low speeds if I hold the throttle at a constant up to about 20 mph. Any ideas?????

 

What have you and the dealership done so far so that we aren't giving you suggestions of where to look next if you have already done it?

 

Possibly the TB. Take it off and clean it out. If that doesn't work then the electronics on the TB may be bad and you may need a new one.

 

The truck has had all scheduled service requirements icluding plugs and all else. Mass air flow sensor replaced, checked exhaust back pressure, and of course hooked up to computor to look for codes with no faults shown. They did say it shows a fluctuation in fuel intake and they don't know why thats happining.

What is a TB? I will follow your suggestion on that but what the heck is it?

 

Throttle body..... https://www.f150online.com/forums/ar...ttle-body.html

 

I have this same surging with mine. I don't really notice the bogging issue, maybe because my foot is to heavy most of the time. I've been thinking it is my CMCV system that is acting up. If it's sticking that could explain your bogging when you step into the gas slightly and it doesn't pick up since it would be dumping more fuel and not getting the required additional air into the cylinders. Then when you really get into it the runners open up fully and there is no issue.

I'll continue to follow this thread to see if you figure this out. I already have new plugs, injectors, coils, and cleaned throttle body and MAF. I also had my intake off during my motor rebuild and I completely removed and cleaned the CMCV runners and reinstalled them and I still have the surging issue before and after the rebuild. Maybe my CMCV actuator has a dead spot where it is electrically hunting between open and close. I'm thinking of a delete kit now that someone here informed me that they exist for this 5.4 3V. I still haven't found the part number.

 

This ^^^.
Problem is exacerbated if using an oiled, K&N type air filter but cleaning the throttle body may clear up your issue. My truck would bog to the point of stalling so clean the TB...it's pretty easy to do in the driveway. You also haven't mentioned other things you've looked at such as replacing fuel filter, injectors, coil packs, plugs, etc.

 

I am having the same exact same issues. New plugs, boots and an induction cleaning did not fix it for me. I am going to replace my fuel filter and remove and clean my throttle body this weekend.

 

Thanks for all the info. I will follow up on the suggestions and let you all know what happens.

 

Hi, Dealing with the bogging issue here too, have done all maint, plugs, cops, cleaned tb and maf. Anyone get this figured out?
thanks for any help

 

Another bogging issue here too! I have done plugs, TB, fuel filter, ect.... still there.... almost like it doesn't know what gear it needs to be in!

 

I had this issue. The dealer reflashed the pcm and fixed the issue.

 

For me it was throttle body, to help assist I would notice my rpm's going done (dip) and come back up then on occasion rough idle. Could not tell how far it would dip until I installed the edge evo programmer (without flashing) just as a diagnostic and it dipped below 400rpm and then would roll up and down between 400-600rpm usually it sits in around the 500 range but would only drop in slight increments (for example between 528 and 534 and roll between these rpm's).

Cleaned the throttle body and it returned to normal. Bog is gone and I have since flashed to lvl 2.

Still going to clean the MAF and I am due for the spark plugs... so hopefully it gets better.

 

Kinda curious if the OP has any updates. I have had similar issues along with other issues lately (hard starts, low power, crappy mileage, pinging). I notice the surging when the truck is cold and you try to drive really slow but keep the throttle steady (barely touching it). I have also had issues with bogging but that seems more intermittent.

 

Hey guys, I have no new info on fixing the bogging problem but I just read the poster who flashed the pcm and fixed the problem so I plan on having that done this week. Will let you know the outcome asap. FYI the bogging is much worse in the summer so it seems I get by ok in the winter and then get fed up in the summer and try to figure it out. Hopefully I dont have to deal with the bogging this comming summer. thanks for the info.