My 2007 GT has about 8k miles and just started to develop a problem where the rpm's hang and do not drop like it used to. Best way to describe it is the rpms drop slowly. So when driving, you let off the gas you normally feel the engine slowdown due to backpressure etc, but now if feels more like the engine coasts if that makes sense. I had a similar problem with my 2000 GT and replaced one of the sensors on the TB (was a well known issue when these sensors went). Just wonderring if this is a known problem with the newer 4.6 3v engines as well? Am going to have the dealer service it, but wanted some feedback before going in. Searched the forum, but found nothing on this.

 

I know what you are saying, and it sounds different than the typical rpm hang that is so common. I know mine when it was stock would "coast" for the first 4-5 seconds after letting off the gas, then it would start slowing down. If that is not the case, try taking off the neg. battery cable for 30 minutes to reset the engine's computer.

 

Couldn't hurt taking a look behind the butterfly valves in the TB, maybe it needs cleaning up. That took care of a similar problem I had.

 

I'll try disconnecting the batterry and see if that makes a difference. I wouldn't think the TB is that dirty yet with only 8k miles, but and easy thing to check. Thanks for the suggestions guys!

 

I've had this issue since new, and I thought all Mustangs suffer from it to some degree. I had read about it before I bought one and even noticed it even during the test drive.

Are you saying that for 8000 miles the revs dropped normally and suddenly started hanging?

I've been told a tune will reduce the hang, but haven't tried it yet.

BTW, I've sort of become used to it...unlike the clunky clutch, which I will NEVER get used to.

 

Yes, this problem started just recently. Although it has never dropped the rpms quickly like other engines I have driven, it wasn't this noticable before.

 

Mine satarted to do this just after installing a new tune with my XCAL, so went back to stock and its now OK. So it's realated to my tune.

I'm waiting feedback from my tuner about this !

 

Mine also does it after installing a tune ... almost like cruise control is always on ...

 

Which tune do you use ?

 

Mine's like dmhines as well.

Like it drives it's self.

My idle climbs from time to time as well when stopped (like over 2,000 rpm).

I'm presently waiting for the dealers "flight recorder". I'll post once we figure out what's causing this. By the way, it's done it since day one on mine (V6, 5 speed).

Took it in once already... NFF


Mike

 

As to the hanging RPMs, did you try "clearing" the PCM? There have been previous posts on this forum about how to do it -- as I recall it involves turning the ignition to the on position (without starting the engine), flooring the pedal, and steadily releasing, or something like that.

As to the clunking noise when shifting, I had the TSB work done for the low speed groan in the rear end when turning. That involved replacement of the clutch packs, and that seemed to do away with a lot of the clunking as well as the groan.