Ford Mustang (auto) - Possible transmission prob?

HELP! Apparently I missed the demo on how to ‘properly’ drive an automatic and am doing something heniously wrong. I’ve only owned a grand total of 3 cars - and this has happened all 3 of those times.

My current car is a 2006 Ford Mustang (V6, automatic), nothing wrong / no prior damage. After a year or 2 of constant driving (I put on a lot at about 25K a year), the problem is that I can feel the car begin to shudder intermittently and drop its RPM’s to well below 500 while idling. It feels like I lose all power whatsoever, and then suddenly the car lurches and knocks like the transmission is going to jump through the hood and the RPM’s kick up to normal. It also happens while driving as well, usually while breaking or decelerating the RPM’s will dip and I can feel that something is amiss. I will rev or accelerate and my RPM’s go up to 2-3000+ with no momentum (like reving in neutral), and then suddenly the car will lurch again, boom - shudder a bit and it’s fine.

This morning my car crapped-out at a red light…I mean it just straight-up shut off. When it was happening I felt it and sure enough the car lurched forward and bam, RPM’s hit 0, car died, battery light came on, car behind me honked, the whole shabang. I quickly took out the keys, put them right back in and started the car up fine - then proceeded to drive to work as normal. My car has a body kit and sits VERY low to the ground - I couldn’t bear it if this thing had to be towed one day, it’ll honestly scrape the road like a belt sander.

For some history here I originally had a '96 Cavalier (auto), and a '99 Mitsubishi Eclipse (auto). With both of them the same exact thing happened, so I know the path towards where I am headed. With the Eclipse eventually the entire transmission just died. I must have taken that car into the shop 5 times prior, and each time they told me they “couldn’t replicate the problem” and everything was fine. Sure enough a few weeks later the transmission died and I spent $2500 out of pocket for a new one. Transmission died again 3 months later, had a warranty so it was fine, and then just after I sold the car the buyer called me and it had died AGAIN a week later!

So yeah…I’m doing something bad to my cars. I drive them decently and hard at times - but not too ridiculously and not all the time. Some mornings I just cruise control it to work. Please help me!

How often do you check the transmission fluid level? How many miles currently on the Mustang?

Well, every time I get an oil change they usually check all the fluid levels and transmission fluid has never been low that I remember. Bought the car 1.5 years ago and it had about 19K miles on it, right now it has about 45K miles.

That’s it, no one can help me out? Thought I would get some more support.

I am absolutely no expert, but have you changed the fuel filter, or had the fuel injectors cleaned? Maybe it just isn’t getting the gas it needs?

You want advice but you’re going to have to provide more information.
Ever had any of the vehicles scanned for codes?
Do you maintain the cars well? And by that I mean regular spark plug changes, no driving around for months with a Check Engine Light glowing, or whatever?

Just offhand, I would say that you’re experiencing an Idle Air Control Valve problem. The IAC is a device that determines the idle speed and is controlled by the ECM, or engine computer.

Sometimes cleaning the IAC can help and other times it requires replacement. It’s also possible to have an IAC problem that will not set a computer code but one with a chronic and severe enough problem should set a code.
IAC faults can be a common problem with any make of car.

Thanks for the quick responses, and I apologize for not giving enough information.

The original Cavalier and Eclipse I took in every time a problem came up and a check engine light came on. I don’t recall any of the codes or problems they got back, but both ended up being tramission problems. I maintain the cars well, if a check engine light comes on it’s a big deal for me and take it in immediately. The check engine light and any other error codes have never come up on my Mustang. The only time anything close ever happened was when it stalled out last week and the oil light came on, but when I started it up it was fine. I haven’t taken it in yet but am going to, and plan on getting a transmission fluid flush, changing fuel filter, cleaning fuel injectors, and telling them to check the IAC Valve, along with explaining the prob. Any other suggestions at all? Thanks all.

I’m not sure that all of the problems here can be blamed on one cause; e.g., the IAC valve.
The majority of transmission failures are caused by abusive driving and/or failure to change the fluid on a regular basis, or even by engine overheating. Severe, chronic engine overheating can overheat the transmssion fluid which is normally cooled inside the radiator and heat is a transmission’s worst enemy.

I would advise that you not simply flush the transmission unless a pan drop and filter change is done first.

The current problem still sounds like an IAC problem to me. Over time the throttle body and IAC will develop deposits which affect the IAC operation and cleaning it is always worth a shot.
If the car seems to run fine other than the intermittent stalling and idle problems then I would not worry about spending money (or possibly wasting money) on a fuel injection cleaning.

Changing the trans fluid every 30k miles is highly recommended and fuel filters should be changed every 15-20k or even more often if contaminations is suspected.
It’s unlikely these 2 things have anything to do with the current problem; it’s just a good maintenance practice. Hope that helps.

I will put it more strongly. All the Fords that I am familiar with REQUIRE transmission service every 30K maximum. You can do it more often if you like.

You seem to feel you are causing the problems with the transmissions, so let’s investigate that further. The “body kit” leads me to think you’ve got some aftermarket “performance” items on your car. Folks who want a car to look like a performance car, often drive like they are in a performance car. Quicker than average acceleration, more foot deeper into the accelerator when passing, and quicker transitions from acceleration to braking. All of the above put more load on the transmission more often and cause extra wear and tear.

If the idle controls on the motor are OK, then it seems the torque converter is engaging and disengaging at inappropriate times. The first item to check is your transmission fluid level. You state that this level is checked when you get the car serviced. That is depending on someone else to monitor the fluid level and sometimes they don’t, and sometimes they overfill the fluid. Get out the owner’s manual and see how Ford recommends the fluid should be checked. Often it is to pull the transmission dipstick with the car warmed up and idling in nuetral, or park. Some dipsticks have the proper directions etched into them. The folks that are checking your fluid may be adding the wrong type of fluid which also causes transmission shifting problems and failure. Take your car to a quality local transmission shop and have them drain the fluid in your transmission and fill it with the proper specified fluid. Then drive it for a week or two and see if it works better. If not, then the same shop can do a more through evaluation, but it could be this transmission is shot too.

Another driving habit which kills auto transmissions is shifting from reverse to drive without using the brakes to bring the car to a full stop. In other words your 3,000 lbs of car is moving backward and you shift to forward and the transmission has to stop the rearward momentum and convert it to forward motion. The internal pressures in the transmission are incredibly high when driver’s do this and it causes premature transmission failure. Obviously the same thing happens when you go from forward to reverse. The brakes are for stopping the momentum of the car, not the transmission. In hign school one friend could only lay a patch of rubber by going in reversed a few mph and making a sudden shift to drive as he “punched it” and got on the gas. One day his transmission left the patch of fluid and shattered metal parts when he blew it out. He was a cool dude that day.

Lastly, do you wait an instant for the transmission to fully engage when you shift into drive, or reverse? The shift at the gear lever inside the car does not instantly engage the transmission. It takes the tranny a second or so to engage. If you are on the gas too soon when the transmission engages it will be with a thud, or a jerk. These jerks and thuds send shocks thru the transmission and cause damage. I had to coach my new driving son to give the car a second or so to make sure the transmission has made the shift and is engaged fully before hitting the gas. Some cars have more of a delay than others, but the waiting a bit is important with all cars.

Look at your driving habits, and maintenance habits and see where you can change to get more life from you cars transmissions.

I guess you aren’t familiar with the 5R55S transmission then.

Thank you all for the thought and time you put into your comments, I will certainly do all of the service recommendations above.

To address UncleTurbo, that is some really intuitive and good insight. You’re correct that I’ve done a few aftermarket mods to my car, nothing major though. Just your typical exhaust work and general things like this, nothing big under the hood. I realize what my vehicle is capable of and what it’s not - and I do drive it accordingly. However I am guilty of the occassional rev and quick acceleration. I think part of the problem stems from these intermittent actions, mixed with a killer commute every day to work (~40 miles each way). I think it just takes its toll on the car trans. after a while.

One of the problems on my stang to go into further detail, is that the transmission is quite atypical in terms of a servicing standpoint. I’ve been told this several times, and really don’t remember the full explanation each time but it goes something like this: The transmission is some sort of ‘special’ or limited addition trans. containing no dipstick, and no simple way of changing it. No regular servicing place can do anything with it unless they take the entire thing apart. The only way to service it is to go to the Ford dealership that is equipped with handling this. I do believe it can be checked at a regular shop - just not serviced. Maybe this is part of the problem, they say they’re checking it but really aren’t?

That is very good info. on the forward / reverse momentum. I am generally pretty good about it, and certainly now that I’ve been noticing some issues. I’ll keep that in mind every time I drive in the future.

Sounds like you do have the 5R55S transmission. Ford calls for fluid flush (it’s really a fluid exchange, there is no “flushing”) every 150K miles only. I have shortened that to 75K with good results so far.

Ok so I guess this does sound like my trans, then that potentially changes my diagnosis into excessive/hard driving, IAC valve issue, fuel filter/injectors, or something else. Do you think I should still have a ‘fluid exchange’ just in case? Only about 47K miles now.

Well, a fluid change won’t hurt, as long as it is done somewhere good. I recommend a Ford or Lincoln dealer for this because few other places have seen this transmission and have the right equipment and right fluid. These transmissions seem to be known for solenoid valve failures. (I just had the valve body replaced on one of my LS’s (100K miles or so)) All that said, your issue sounds like engine and not transmission.
As for the IAC, I really doubt that your 2006 has one. Most Ford/Lincoln/Mecury are now throttle-by-wire, and throttle-by-wire setups don’t need or have an IAC.
I believe that your V6 has a nearly hidden PCV. My understanding (don’t have one myself) is that the elbow to the PCV gets old and starts to collapse and split. When this happens, the symptoms are just what you describe. I think the intake manifold has to be removed to get to the elbow. I’d check that if I were you.

Other than pointing out that Ford automatics get pretty touchy if the fluid is not changed on a regular basis, I will have to respectfully disagree that a Ford dealer only should be utilized for a trans fluid change.

Recently my son had this done to his .04 Aviator at a Ford dealer to cure a very subtle and near unnoticeable 2/3 shift flare. He got the vehicle back and it was almost undriveable due to bucking and jerking transmission shifts. According to the service manager the vehicle was “fine”. Right. Slamming you back and forth on the seats is “normal” with most shifts?

After I had some discussions with the serv. manager he admitted the car had a problem and according to him, quote: “We haven’t dropped a transmission pan here in 15 years”. End quote. They simply flush them and call it good.
I proceeded to tell him that their method is not the proper one and that I knew exactly why they did it this way - speed and profitability.

So after bringing his car back in, dropping the pan, and actually cleaning things out the vehicle has been fine up to this point; knock on wood.

After a discussion with a life-long friend of mine (40 years in the transmission business) he said that almost all of the dealers around perform a flush only now with no pan drop.
A number of emails with corporate FOMOCO asking them to clarify Ford’s position on flushing only/no pan drop has led to nothing but fence straddling (“see our local dealer network for the finest technicians, latest equipement and technology, etc”) and a refusal to even clear up what they mean by stating in the owners manual, “change transmssion fluid”.