I'm having a problem with a bump between 45 and 50 miles an hour or 1500RPM. As it goes through acceleration and get to this point it will bump 2 or 3 times pretty hard. I can turn overdrive off and it doesn't do it. There is no code, check engine light nothing. At highway speed it runs fines.

Am I looking for an ignition problem or a transmission problem? Need a starting point please.

 

Some details I left out. 148K milage, transmission was serviced 40K ago and plugs have about 50K on them.

 

Ignition. It's a low grade misfire, bad plug(s) or cop(s).

 

Listen to GLC on this one. Had the same problem with my 5.4 in overdrive trying to speed up at around 45. Feels like the transmission I know, but turned out to just need plugs. But like he said, may be a bad cop also.

 

Cool. Thanks for the input. Now I know where to start.