Hello fellow Ford people. I found several posts about this problem but I tried most of the fixes but cant figure it out.



I bought an 07 F150 5.4 4x4 with 135k on it about 6 months ago. Shortly after buying the truck I began experiencing a shudder when lightly accelerating up a hill. Also when accelerating hard it would misfire. Thinking that it was plugs or COPs I changed the plugs and coils. That fixed the missfire issue but it still shuddered when accelerating up a hill. I decided to take it back to the used car dealer where I bought it so they could fix it. On the way there the fly wheel broke. The dealer replaced it and thought that it was the cause of the problem but on the way home I still experienced the shudder. I took it back and they "scoped" it and found that the torque converter was bad. They replaced the TC and now there is no more shudder BUT now I have a new problem.

Now if I am driving at highway speed and let off the gas it feels like it immediately down shifts for a few seconds then shifts back up and coasts along until I give it gas again. There is enough resistance that it feels like a jake brake or that the breaks are being applied. Also if driving along at 30 - 40 mph and just holding the gas in the same spot maintaining 30-40 it feels like it down shifts and up shifts over and over until I either give it more gas or let off all together. Also a few times pulling away from a stop I will get a thump.

I have an appointment with a transmission shop in a few days but today on the way home I put it in second gear while going up a hill so it would not shift and it seemed like it was coughing and sputtering. So now I am wondering if that is what is happening and either feeling like or causing the down shift up shift issue.

Any ideas? If it is a missfire issue why would the new torque converter cause this? It has all new motor craft plugs and all new after market coils.

There are no check engine or other warning lights lit on the dash. I have a cheap ODB scanner and it shows two codes. B1676 which apparently is a Battery Pack Voltage Out Of Range or ABS voltage issue. The voltage is showing at 14.2 volts and there is no noticeable battery issues. The second code is a P1000 Drive cycle test not complete. (this code has been showing for some time the 1676 code is new since the torque converter swap)

One side note: after the TC change every time I start the truck the radio/cd changer cycles though all the CDs. like it it is checking for a disk so it clicks and pops around from a moment. The only time I heard this happen before was after having the battery disconnected. The clock is not reset though like I would expect if it was losing all power. May not be related but who knows.


Thanks in advance for any help.

 

Today pulling away from a stop sign it felt like it slipped then a big thump and it took off. something definitely is amiss....Well its at the tranny shop now hope to know the cause tomorrow.

 

Well I took the truck into a transmission shop and they did some test s and determined that it was the transmission. Apparently this transmission is known for a problem which allows the transmission shift to from a gear to natural for a split second then slam back in or to shift back and forth between gears randomly when not under much load.



2500.00 later the transmission has been rebuilt and it seems to be working great. So all the money that went into the torque converter was wasted because they had to replace the TC in order to warranty their transmission rebuild. So my advice if you are having this issue would be to take it to transmission shop to get checked out before letting your mechanic just replace the torque converter.