I have seen a lot of post refering to a shuddering in the last gear. Some say it is a coil and plug and others say it is your torque converter. I am confused. How can you tell the difference. What if there is no codes showing up. Here is my scenario.





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I have a 2001 4.6l f150 supercrew (76,000MILES)and i have the same problem as you stated.. I have taken my f150 to the dealership 3 times and they can't seem to reproduce the misfire or whatever seems to happen betweeen 40-50 mph. I only happens under a load( like going up an incline)and moderate to mild acceleration. It also only occurs when shifting into the overdrive gear. If you acclerate hard it goes away when you pass 1500 rpm. I tried to take it in to the dealer and on the way a plug and coil went out. The error code came up and they thought they fixed the problem but it still is not right -but it is a little better. It is really frustrating. This happens everyday atleast 20 times(no codes though). I can almost eliminate this from happening by turning of the overdrive.???? Is that crazy?I wonder if changing all of the plugs might help? all of the coils too? I only have 75000 miles on this engine and it really makes me mad that the ford dealer can't figure it out. This has been going on for 1.5 years! I looked around and didn't see any fluid leaks.

Since this post I have changed the #1plug,#8plug, and the pvc valve. The boots were fine and the plugs looked okay. I have changed the trans fluid and cleaned the injectors twice.
Should I just change all of the coils and plugs? is this a waste of time?
what about the cables?
should i make the dealer change the torque converter?

 

sorry...cant answer your question...but damn, ur truck is still running after 760,000 miles? lol

 

Our conditions are certainly different, but the buckin and all is what you'd get if your fuel filter was partially plugged. Mine was doing that same thing, under a load, and the wife had the filter changed and it quit that for a long time.
It's about time for another oil change and it's bucking a little from time to time.

 

If it's not the fuel filter:

Had a similar problem with my 4.2 V6. Usually happened when under load, on hills, in 5th (od) gear. Hooked up my laptop (with AutoTap scanner) to the OBDII and it showed what was called "Low Word Cummulative Misfire" on the #2 and occasionally the #5 cylinders. Could only feel the mis on #2 and it never threw a code and no one has been able to tell me what a "low word" misfire means. Checked the primary and secondary systems with an Ohm meter and all looked okay except the aftermarket wires were not to OEM spec. Changed all the wires (not a COP) with OEMs and it helped for about 200 miles. I know with the coil-pack the plugs fire on both opposing cylinders at the same time. Have since swapped the wires for the #2 and #5 at the coil pack and the shudder has gone away. Not exactly sure why but happy it's gone.

Given that you have a COP system the only thing I can think of is checking everything with an Ohm meter. If you don't find anything specific you'll probably need to replace them all. With 76k I assume you're running the original plugs?

 

I had the same problem you described, Missing under a load or moderate accleration. Otherwise the truck ran fine. My 98 4.6 has spark plug wires and a new set of wires fixed it. Not sure if this info will help since your truck has cop.

Good Luck

 

"Low Word"??? Could that be programmers jargon for the least signifigant digits of an 8 bit word? (some octal systems used an offset to get two words into one memory line)

Maybe meaning, when the PC left the closed loop to the open loop, the load increased, and the first thing the PC noticed was a Low current condition to the Coil, or a low O2 sensing? That might be the first word?

Not enough of something the PC expected to see, but it was a soft error and corrected itself quickly.

So get in there with your laptop and read out the Rom's and decode them with your emulator. Then we can guess some more, but with some more meaningless facts to cogitate with.

 

Thud, I'm not sure why my head hurts after reading your last, lol.

I thought it might be something related to current to the plugs which is why I switched the wires at the coil-pack. Whatever, it worked. Though I still get random low word mis readings occasionally, I can't feel them.

I wonder how sensitive the system is to wire length.

 

Nope! One of the systems in an R n' D lab I toured was like that. Three Processors, in wall cabinets. Multiple Disk Drives, redundancy and all that stuff. Very high speed stuff. Signal timing had to be soooo correct.
Every wire in the Processors was precisly the same length. All white too.

Our little PC is probably an off shoot of something like a 10Mhz processor. It's sleeping in between I/O functions at that speed.
Somebody knows what those 'Low Words' are. The names come from jargon. I dont think the phrase 'Low word' is an kind of industry standard phrase.

 

is it smart to switch COP wires ie 1-4,2-5,etc Do you think that may take the shudder/slip out of the high gear.

 

bdski,

Unless you can find some one who can pinpoint the mis I think changing the plug/COP wires is probably the best place to start. I'd recommend staying with the OEMs.

The only way I know to find a random mis is to have a realtime scanner hooked into the OBDII while driving. If you're in New England, not to far, I'd check it out for you.

Thud,

Just wish some one would let us in on the jargon.

 

My 01 supercrew 4.6 V8 had a "shudder" problem when under load, up a hill, or when shifting. It turned out to be water in the back two spark plug wells. My neighbor (service manager at the local Ford store) told me that sometimes rain water leaks onto the engine from the joint in the cabin intake (where windsheild wipers are). My back two had about an inch of water in them and never threw a problem code. I sealed the junction and have not had the shudder problem again. Also make sure to clean the COP boots because they will continue to arc. This may not help you, but it sure did me.
Of course now I have the P0401 code. <see post>

Richard

 

Don't rule out torque converter "shudder". Changing the trans fluid should help.