Today I changed out the fuel filter on the 98 4.6L. No joy on the hesitation issue. So, I pulled both coilpacks and checked them. They checked a little high on the cylinder-to-cylinder measurement, so I went ahead and replaced them with parts from the local NAPA store (made in U.S. surprisingly enough). I also pulled the MAF box and cleaned it with contact cleaner as recommended on the board.

Test drive and...worse than ever. I guess I'm going to have to drop it at the mechanics unless someone has some more ideas.


The stumbling is very intermittent. There's just no pattern. Sometimes at idle, sometimes not. Sometimes just going down the road, sometimes not.

 

changed the fuel filter yesterday and it helped...a little.

im guessing that i was the first one to change it at 50000 miles. it was almost impossible to blow through, and when i blew through it from the engine side you should have seen the unholy crap that came out of it. it was the color of runny oil, not fuel..

anyway i guess im going to change the plugs next.
i have 2 questions though. what kind of plugs do you guys recommend/not recommend? also, how the heck do i go about getting the far aft drivers side plug out with all the hard lines just above the hole??

i think its a conspiracy, ford doesnt want me to work on my truck, and i dont like it!!!!

thanks again for the help everyone

 

check your o2 sensor or sensors.

 

..

 

The easiest way to get to the driver's side rear plugs is by removing the fuel rail. Relieve fuel pressure at the schrader valve on the passenger's side rail. Then remove the two 8mm bolts that hold the driver's side rail and carefully pop the rail off the injectors. There will still be some fuel leakage! (it will evaporate away by the time you're done). When putting the fuel back, coat the injector o-rings with a light oil.

 

i got around to changing the plugs today with motorcraft, and it wasnt as bad as i thought it would be.. about 2 or 2.5 hours, not bad for the first time i guess. the plugs actually looked pretty good, a little whitish buildup on a few. isnt that a lean indication? oh well, they werent bad..
i did notice that the new plugs had almost twice the threads as the old ones. the P/N was the same as the old ones with the exception of a "p" at the end. anyone know whats up with that? the guy at o'reileys said that they were the ones so thats what i got.

so now comes the test drive, it started, so i guess thats a good sign. it seemed to be doing fine under all conditions.(idle, light load, full throttle etc.) needles to say i was pretty happy, when of course it happened again.... partial throttle going up a hill, and bam, there it is again. not as bad, but it was still there.

oh well, my plan next is to test the O2 sensors and go from there.

what do you guys use to clean the MAF sensor??

BTW: i put a can of seafoam in the tank and didnt really notice any difference, but i guess it didnt hurt right?

thanks again for the support

 

any luck with this? I've got an 01 screw with 5.4l doing the exact same thing. Autozone will scan your codes for free (you can have a code even without a check engine light). I had them scan mine and it showed a misfire on cylinder 5

I replaced plug & coil and it seemed better for a day or two - the old coil had rust all the way up the boot - water got in there somehow.

Now it's doing it again (not nearly as bad though). I'll go get it scanned again as soon as I get a chance.

 

I think I finally fixed mine today. Had a couple of really bad days with it and it set a code (worse in damp weather). Had it read at Autozone; misfire on cylinder six.

Turns out that this was the very wire that I was getting a blue glow from pushing on it the other night. Sooo....

Bought a single wire today from the local Ford dealer (only place to get a single wire I could find) and installed it (pulled the plug and examined it first, but it looked good). Managed to get everything put back together before dark, jumped in and fired it up...&^%$&!! Now I've got a dead miss somewhere. Oh yeah, it would help if I plugged the fuel injector plug on Number Six back in.

Taa Daa...no more miss and smooth as silk on the test drive. Hopefully that will continue.

 

I changed my plugs lastnight and the back two cylinders on the passenger side (3 & 4) were filled with antifreeze.

It's running better now, but theres still a little miss - could those coils be fried from the antifreeze? Where could it be coming from? I saw a heater hose that runs right over them, but no trace of a leak...

 

I have to take that back - it's no better

It seems to only happen under load, and I've noticed that it backfires at WOT shift from 1-2. I had the computer checked and there are no codes...I don't know what to do now.

I'll try changing the fuel filter tonight - any other ideas?

Would a dirty MAF throw a code? What should it be cleaned with?

 

I had the same problem on my 4.6 (99). I lived with it till one day I changed the spark plugs.......It never happend again and its been over 10.000 miles since.....I belive one spark plug had a foul at certian throttle positions, Like I said, changed the plugs, it went away.....

Mike

 

i know u guys pretty much have this thing down to plugs, coils, or maf system. and some have been fixed and some not. but i keep hearing all this stuff about the fuel filter. maybe its a problem with teh fuel injection system on the truck. i recommend bringing it to ford and getting it diagnosed. then bring it home and fix it youself.

 

I have done all the things that most of you have suggested and mine is still doing the same thing. ( with no check engine light)I have a friend that works at auto zone and is a mechanic. He suggested replacing the Throttle position sensor (TPS), or the EGR, but most likely the TPS. Said it worked on his E150

Does that sound feasable to anyone else?

This problem really seems to be a nuisance for Ford Trucks.
Even on new ones, so I've read.

Here's what I have done so far:

Changed plugs, wires, cap, rotor, fuel filter, air filters, O2 sensors (L&R banks), PCV valve.
Cleaned MAF sensor, flushed fuel system.
Engine flush with oil change, fuel system cleaner additive, heat, high grade gas.
Changed tranny fluid and added friction modifier.
Changed tranny filter and modulator.

NOW WHAT! I love my truck, it's my first one, I want it to run right.
Why is this so hard to trace?
I'm tired of spending $$$ on stuff that doesn't fix the problem. So..... TPS or EGR? (TPS= $32.00 EGR= $72.00)

Someone has got to have found a solution to this. Please step forward and tell us what to do, plz!!!!

:<

 

I brought my truck to a mechanic and he couldn't find a problem....

He says if the coils get wet (like mine did) they should be replaced. The coils breakdown over time and getting them wet accellerates that. Even if they test fine, they may have a problem.

I mixed the two that were wet in with the two that were not wet (on the passenger side), so I don't know which two they were...I'm ordering 8 from Mike T monday - he's got an awesome price on them.

I'll post again with results after I install them.

 

ok, another update.....

i checked the pcv valveand the maf sensor (i think..) yesterday.

the results?? same old stuff...

the pcv valve was sucking like a champ at idle, so its good right?

maf..... is the element the one just downstream of the airfilter? in the convuluted pipe that goes from the filter to the intake? if so, it was clean as a whistle....

i cant believe that as common as this problem seems to be on the 4.6 that there is not one suspect component in the system.. how dissapointing.
overall i love my new truck, but this is ridiculous.. a miss before you even hit 60,000 miles?

another question, can the computer set a code without illumionating the ses light??
if so, ill have autozone check for me before im forced to take it to the dealer and have them tell me they cnd, or tell me that its my fault.........

the saga continues