I've got a 2007 Night Runner. We were coming home from our trip for Christmas and we came across a weird issue.

We were cruising at about 75 mph and you could let off, the rpms would drop off low and when you hit the gas again you could feel re-engagement and a bang noise.

It hasn't done it again since it did it repeatedly during our drive. The D has 41k on it. I don't know if it's a lockup issue or what. Any ideas?

 

Did the check engine lite ever come on? And have you checked for any stored codes?

 

No CEL or previous codes. I have HP Tuners and I scanned it and there wasn't anything.

 

Possibly the universal joint?
FF

 

That wouldn't make the rpms drop like they did. They were about 2200 and dropped down to 1600. You give it gas, you get the bang, and the rpms come back up.

 

Throttle position sensor,
FF

 

Is this what were talking about?

Vehicle Issue Slight engine RPM flare up noted at 3-4 shift point.;Applies to 2006 - 2007 models equipped with 545RFE automatic transmission. Slight engine RPM flare up may be noted at the 3rd to 4th gear shift point.
System or Component Upshift / Downshift Issues;Customer Concern (No DTCs);3-4 Upshift;Yes - Intermittent,Yes - Continuously
Recommendation The cause of the slight engine RPM flare up at 3-4 shift point is a controller software modification made in 2006 which now performs the 3-4 shift while the torque converter clutch (TCC) is in partial lockup mode. This is normal operation and was implemented to improve fuel economy. Generally, the engine speed increase during this event should not exceed 150 RPM.

 

Not really. This occurs while we were on the interstate in traffic. We would be cruising at 75-80mph and have to slow down, so you let off the gas. Once you get back on it, the bang occurred. Not during a shift because we are already in 4th gear.

 

There was an earlier thread about a weird noise during acceleration and it was the sway bar bushings needed replaced. My Demon would do the same and the control arm needed tightened,
FF

 

I would like to hope that it was something like that, but I looked underneath and I didn't see anything that looked abnormal. The rpm drop leads me to believe it's mechanical or computer related.