Mattstruck

I have the same problem. I received a P0430 code for catalyst under eff threshold in bank 2.
Do you think changing the cat would correct this SHUDDER as well? or should i change out the COP's and Plugs?
I am not getting an engine light for the coils or plugs, but i am for the Catalyst eff below threshold. Just so happens, that i also have a bad SHUDDER like going over a washboard when i am in lower part of the gear, like when accelerating at 1100 rpm or on a little hill...
the person i bought the truck from said they changed the coils for me before i bought it, but now im thinking there is NO WAY...
can changing the cat fix the shudder alone?

Please PM me if you have some info. Thanks in advance.

Birds Nest

Update.... turned out to be the plugs and COP's. I finally got it to trip a code, so I had my local mechanic put it on the reader and it came up with a #4 coil misfire. He changed out the coil, and it ran fine for a few days, but then the problem started again. Took it to the Ford dealer (Sunrise Ford in Ft. Pierce, FL - highly recommend) who suggested unless I changed the plugs, the coils would keep failing. I had the all the plugs changed, and the #2 coil replaced as well. They also recommended having the throttle body cleaned. Add in a new fuel filter and we're out the door for $995. Everything seems to be running well now. Keeping my fingers crossed.....

ekonkjack

Last Thursday my 05 F150 with the 4.6 started to run like s**t. Big loss of power and a very disturbing shudder when trying to accelerate. I was about to bring it to the dealership but decided to change all the plugs and inspect the coils while I'm at it. After all, I have changed spark plugs in every motor that I've owned since the mid sixties. First off came the coils or COPs. The ohm meter readings were the same on all but one and when the plugs came out the plug under the different reading coil was pretty nasty looking. New plugs and one new coil and all is well. About $80 and three hours worth of work.

Steven P. Banks

I bought a 2006 expedition recently and I was having this same problem, I checked the forums and it seemed to be a regular problem that a lot of people where having. I took my truck back to the dealer on four different occasions for a misfire problem. I found out about the spark plug issue when they did a tune up on my vehicle. I found out how difficult it is to do a tune up on the 5.4 triton engine, which ford should take full responsibility for but won't. Well after a long and exhausting search, I thought I was just going to have to put up with the shutter until the truck just eventually shut down completely.. But luckily I took it to my old mechanic and they found the issue, The intake manifold was leaking coolant into cylinder #3, so if you have done a tune up, and your still getting that shutter at 40-45 mph check your intake manifold, it might be leaking, be prepared to pay. it's costing me a grand. but hey at least it's fixed finally.

LEN671

Any updates on this situation?