I have a 2007 screw, 5.4L with 58k miles. I've been noticing a weird vibration when I'm driving on the highway in overdrive. I don't notice it when I turn the overdrive off. It happens when I go to accelerate and it shifts down, right after it shifts. The vibration almost feels as if I ran over the rumble strips on the side of the road, but not quite as intense and just for a split second. Any ideas/suggestions on what it could be or what I should look into?

 

I had the same thing happening to my truck. Mine was under warrenty I took it in and they had to replace a bunch of parts and my transmission case. I guess a shift silo. cut into the case and damaged it. Get it to the shop ASAP if your still under the powertrain warranty. They said if I waited much longer the case would have come apart but the problems your having are the same I'm having.

Jon

 

Thanks for the reply, I think I'm going to head to shop this afternoon. I bought the truck used and i can't remember how long the powertrain warranty is

 

What you have is a coil pack that's beginning to fail. I had the same exact symptoms and dealer was ready to dig into tranny, I said no thanks. You are probably getting this at around 50 mph and it will come and go intermittantly. If it were a rotating mass that were out of whack it wouldn't come n go. What you can do to try to get ecm to put out a code is turn of OD and gun it. This will cause bad coil to misfire and direct you to the cylinder with the problem. This has worked for me a couple of times. Or wait about a month before it gets worse and throws code. Just b very careful about letting dealer tear into it, they aren't selling cars so they will look for any excuse to stick you with unnecessary repairs

 

Yeah that's why I'm being very cautious and trying to do research on the possible causes. I had a coil go bad on my old camaro so I have an idea how that was. The only argument against the coil I have is that I never notice the vibration any other time other than on the hwy with the OD on when it down shifts. I can put the pedal to the floor with the OD off and not feel anything?

 

Stock powertrain warranty I 6-60. Your covered. Take it. Trust me it's the transmission. You get it only SHIFTING out of OD. That's what I had. If it's a coil pack going bad your problem will happen in any gear not just OD. Like I said, no matter what it is your covered under the powertrain warranty. You have any worries call your local dealership and tell them what you have year and miles and that you got it used and they will say yeah it's under warranty bring it in.

Jon

 

I'm Taking it over in an hour, no taking any chances

 

When your torque converter locks in over drive and the rpms drop It puts a big load on the motor which will make it missfire with a bad coil. You have a bad coil bud.

 

And when it downshifts to 3rd that strain is takin off the motor which means no more missfire.

 

That makes sense. I dropped it off at the dealer earlier since it's still under warranty. Going to see what they come up with and then go from there.