First off, Awesome site. Glad I found it and it has walked me through the first part of this witch hunt.

Unfortunately I have hit a wall.

2001 F250 4x4, 5.4 with 214,XXX on it. I had the infamous bucking show up under light load 1100-1700 RPM and changed the plugs and boots as soon as I did some research here. The truck ran great afterwards...until about a week ago .We are back to square one with the bucking but now it is worse and I also have a weird starting problem. A few days a week when I start the truck it will immediately start to stutter and die. Crank it again and she is purring like a kitten.

I went out today and checked all of the Coils with a HEI spark tester (All fired fine) and went ahead and had a buddy brake torque it so it was under load and unplugged the COPs one by one...No bad one found. Also cleaned the MAF, You can eat off of it.

The starting problem lasted around 3 days, Did it every time I started it hot or cold but then went away. Hasnt done it at all the past 4 days. The stutter however is here everyday, every night, hot or cold.

I am looking for the next thing to check because I do not want to have a shop crawling around on it for 3 days racking up the bill. Can I test the EGR, O2 sensors or look for a common vacuum leak that would cause this?

On a side note, When you rev it up in nuetral to around 2400 and let off it has a slight "bird chirp" sound right at the moment you let off. This also happens when you start it. Almost sounds like a belt slipping for half a second but the belt is only a month old.

P.S. - No CEL, No codes stored.

Any help would be greatly appreciated guys and gals. This thing is driving me nuts.

 

Also, When I was in there checking for spark I did not see any oil or coolant in the plug wells. All were clean and dry.

 

LOL...Also, Not sure if this is a common noise on these trucks but if you hop in and turn the key to on (engine off) and wait a second it will let out a good "sigh" 5 or so seconds later. Coming from the firewall, Drivers side. Vacuum booster? Should it do this? Could this point to my problem?

That should be the last one, Wanted to get all the info on the table at the beginning.

 

The sigh you hear I believe is the evaporative control on the fuel system opening, relieving any pressure and admitting fuel vapor into the induction system for the afterburner effect.

As for your bucking problem----do you have an Idle Air Control valve? Check its operation. I know that will definitely affect the idle but not sure if it can affect the above idle performance as you describe.

Also I've had that same bucking or rough idling issue but it was due aftermarket COP's temporarily shorting out when outside temps dropped below 28* overnight. Fire the engine rough idle and CEL of course. Warm up to operating temp, shut engine off and immediately refire---all is well---until next cold night anyway.

Might be smart to check the individual spark plugs----its possible one or more of them have failed. I'd think if that were the case though you'd thrown a code of some sort. Maybe measure the exhaust manifold at each cylinder to check if you have balanced combustion?

Not sure what else to suggest at the moment..................

 

I've got the same problem with my "05 5.4. Comes in around 1200 rpm. Prior to buying this truck, I told the dealer that it had quite the hesitation on acceleration. Supposedly fixed it. I wonder if its all tied in together? It also threw a 304 code which is related to #4 plug. Cleared the code and it hasn't happened again. Couldn't see the darn plug although I know its in there somewhere. This is a slightly lifted FX4 so its a problem getting around the engine area. Gonna build some steps to hang on the wheels. I'm going to clean the IAC, MAF and the EGR and see if this all helps. Plugs are next in line, especially since I don't know when they were changed last.

Here is a tip for you guys, I have used the Case IH anti-seize & lubricant (read gray lead) on spark plugs, nuts and bolts, etc. especially wheel studs and have never had a galling problem leave alone a seized nut or bolt. Its great stuff. We'd use several cans when putting a Case tractor back together. Works on diesels or gas rigs. Any nut- - -any bolt!

 

dWell now this is getting interesting. Can't find the EGR but it has a cooler? Don't have a MAF either. Hmmmm- - - -strange.
Cleaned the IAC, blew out the garbage from around the plugs and on top of the engine. Will have to pressure wash around the plugs as it has "mud" and dirt that won't blow out.

I will check the # 4 plug COP to ensure operations- - - - but?
Will have to get a better shop book that covers the late model 5.4s.

 

OK- - - it don't have a cooler for the EGR! Apparently it sthe diesels- - - -

 

If I can jump into this thread please....I am new to the form and been looking for a conversation of this nature of the 5.4 stuttering when cold at idle and when trying to accelerate. I have an 03 Expedition with the 5.4.

The engine runs rough when it is cold and actually behaves the same way when it rains a lot...almost like it has a moisture issue at times? I changed the plugs, coil packs and the IAC Vavle..and it still runs rough first thing in the am. I brought it to my mechanic friend and he stated it has everything has to do with slow oil flow getting up to the cam and throwing off the variable timing...I am only repeating what he said, I am not knowledgeable enough to go beyond that.

My question is this: The check engine light has been on for 2 years because the code it keeps throwing is for an o2 sensor and the catalytic converter. Could that cause the truck to run rough when cold also.

My mechanic friend is confident in his diagnosis and said just drive it until the engine dies since it is not worth the $$ to do all the cam, timing chain and a screen at the top of the engine that gets plugged, supposedly stopping oil to flow up to the cam.

The engine has 240,000 mile and actually runs great when it warms up. I have been running MC 5w-20 in it as recommended for years. I can turn a wrench, but I am not knowledgeable enough or experienced enough to dig deep into an engine.

I am still trouble shooting and hoping it is not the oil flow issue up to the cam. The engine does not make any knocking noises at all.
Thoughts?