No codes ever to read. Never even threw a code once... the truck has horrible throttle response yet you can gradually input throttle fine all the way up to high RPMs. If you are quick to throttle there is hesitation that feels more like speed limiter. Sometimes a stumble at idle or when driving.

I have once replaced the coil packs (for a different symptom) with Motocraft about 18 months ago along with wires and plugs. I have only stock computer and no chip/program. Is this the coil packs arcing? Should I buy Accel?

Could the MAF sensor be flakey (I've cleaned per order of other posts)? Once again no codes. And yes I have repeatedly reset the computer after half hour disconnect of battery. Nothing to go on here. Maybe fuel injectors? Fuel Filter has been replaced with no difference.

4.2xl2001
Std. Short bed 5 speed 96k miles
Gibson Super Truck
Air Raid intake
4.10 Gears
18" Toyo Proxes on Fake L wheels
Mark VIII elec. fan
ASP pulley
Rhino liner/ Downey Cover

 

Check fuel pressure? Clean injectors? Can't believe its not showing a code if it's running that poorly.

 

Maybe you are clearing the PCM before it completes a drive cycle. Try to keep driving it longer to generate a code.

 

Hi

Sounds like the same problem I had on my 2002 5-speed at 59,000 mi. Never had any codes. New plugs and BG Induction System cleaner fixed it.

Harry

 

I have cleaned TB and area leading up to it including MAF sensor. Last time I checked plugs all was fine.

I haven't lost significant amounts of coolant since new (maybe added a quart total) however I have seen some dark coloring to the coolant. I am really interested in ruling out the lower intake gaskets which have never been replaced. Once again I have owned this truck since day one and most mods except for ASP pulley and E fan were done in the first year.

 

I have seen this post a few times on this forum. There have been a few suggestions but never a hard answer. It sounds like you are having the same issue as I am. I also replaced the coil pack, plugs and wires late last fall. I was just about to make a post asking if anyone has pulled the intake manifold to clean the EGR ports. I did this on my Windstar last summer. It made a huge difference but pulling the manifold on the F150 seems a little more daunting than the Windstar so I have been trying to eliminate all the other possibilities first. I cleaned my MAF last fall also but I am thinking about replacing it now. No codes at all here either so it is tough to chase down the problem. This seems pretty common with these engines so I am surprised it is so hard to chase down the problem.

 

You sure are right. I would buy the new Accel coil pack if my replacement Motorcraft is at fault. I may try my original coil pack (which I saved) if only to rule out the old part. Cleaning/inspecting plugs may buy some time too. Fuel pressure is something I haven't tested. Maybe pulling each fuel injector one by one and cycling ignition power will allow an inspection of spray patterns.

But the problem is I don't have a clue what to look for in general for this hesitation/throttle response problem.

 

I almost waited to take this to the dealer for a quicker solution.

While inspecting my old coil pack replaced a year ago, I decided to swap out the one I replaced it with. After removing the replacement part to compare part numbers and verifying my replacement was the updated MoCraft part #, I decided to inspect the plug connection and ground. They were fine. Finally, I insected the three 7mm bolts that hold down the coil pack. They were corroded in all the right places! Scotch brite and a wire brush fixed this complexing problem. I reinstalled the good part with the newer part #. Now I can mash the pedal in fourth gear at 30MPH with smooth acceleration again.

I hope Accel supplies new bolts with their upgraded coil packs for everyone.

 

Did your engine ever run real rough after a rain (or snow) storm. Mine does this. It runs like someone pulled a plug wire off. After about 2 or 3 minutes it smooths out except for the hesitations descibed earlier.
Glad you got yours running good. I will have to check out those bolts also.

 

Yep Dan,

The hesitations were worse as it the air got dryer.

tom
4.2xl2001

 

The bolts started to corrode again and the hesitstion came back very slightly this time. To cure this, I used a piece of audio amp supply wire to strap from the coil pack (under one screw) to the chassis. I also used an adhesive/sealant to keep the clean connections water tight.

hope this helps anyone else.

 

I got mine fixed but I think it was my own doing. I just started using dilectric grease in my spark plug boots last summer when I changed plugs last. I think I added to much grease and was getting the intermittent hesitations because of it. About a month ago I bought the Autolight Iridiums and installed those. I cleaned out the wire boots real good and just used a thin layer around the inside of the boot this time. I thought I had a bad plug as one of the old plugs that came out was black around the threads and the tip but I think NAPA just sold an older version of the same plug as the blackness wasn't oil deposits. After I cleaned it up good it was the same plug just a different look to it I guess. Anyway, all is good with my truck so far. My wife just took the passenger mirror off the van by way of a construction barricade. Funny how stationary objects tend to jump out at her when she drives. The fun here never stops!!