2011 SHO. Shuttering on the highway with a/c on

[diponyou]

I've noticed that when on the highway with the a/c on and I attempt to give it some gas (3/4 full throttle) the car shutters quite a bit. It is an intermittent issue, most of the time it's fine.

Yesterday my fiance and I were driving to dinner and I got on it while on the highway and it shuttered really bad and it was like the transmission forgot what it was supposed to do, the revs went way up but the car didnt accelerate than it shifted really hard into gear.  :-

I am doing plugs either tomorrow or the next day, and its going into the dealer tomorrow for a ptu fluid change and oil change. They are going to see if it has been reflashed, and there has been a dragging noise coming from the driver front wheel that sounds like brakes.

Any ideas? 

[BiGMaC]

Check the TSB on the tranny and the one on the half shafts... They are posted here.  Larrylu has had these symptoms and TSB seemed to fix it by replacing some tranny valving.  This fix is over and above warranty.

As far as the tuning... They can tell you accessed the OBDII (like with an MX or an Aeroforce gauge... But would need more specialized software to see what was done.  At 88k aren't you out of your warranty?

[diponyou]

Check the TSB on the tranny and the one on the half shafts... They are posted here.  Larrylu has had these symptoms and TSB seemed to fix it by replacing some tranny valving.  This fix is over and above warranty.

As far as the tuning... They can tell you accessed the OBDII (like with an MX or an Aeroforce gauge... But would need more specialized software to see what was done.  At 88k aren't you out of your warranty?

Yes I am out of warranty but I do have an extended warranty that will cover that stuff if that is the problem.
It isn't tuned yet so there shouldn't be any issues there.

I heard someone say that you have to wait 30 days to use the warranty because they will blame it on the dealer I bought the car from. I really don't know if that is true but I don't want to deal with that.

I am hoping it needs a reflash, that will get me through until the 30 day mark at which I will bring it back in if the symptoms continue.

[diponyou]

One thing to note, it doesnt do this with the ac off

[ZSHO]

Best of my knowledge there a 30 day lemon law in most states,that reputable Dealer must perform any mechanical issues that come to arrise for 30 days even internal engine problems which many warranties wont cover,good luck and hold off on the tune until you get these issues rectified,

[diponyou]

Unfortunately arizona lemon law for used vehicles only covers you for the first 500 miles or 15 days. I've surpassed the 500 mile mark.

[wasinger3000]

You should try to watch a few engine parameters while you wait for the 30 day mark. See what's going on.

[diponyou]

So here's an update.

The ford guy called me and said the shop foreman won't change the fluid in the PTU because it's not recommended by the service manual.

He also told me that the PTU was replaced at 60 thousand miles.

It was also never re flashed. I asked the guy what the re flash would do and he didn't know. He said that it doesn't tell you what it's doing.

[SHOnUup]

So here's an update.

The ford guy called me and said the shop foreman won't change the fluid in the PTU because it's not recommended by the service manual.

He also told me that the PTU was replaced at 60 thousand miles.

It was also never re flashed. I asked the guy what the re flash would do and he didn't know. He said that it doesn't tell you what it's doing.

Customer service seems to be a long lost art, unless talking to Torre or EPParts from what I see.

[kinder]

Shouldn't matter if the PTU is 'due' to be flushed as it is a customer pay thing. That's like you bringing the car in for an oil change after 3000miles and they say they won't do it as it's not recommended till 6000.  Maybe a new dealer is in order?

Does the shuddering happen only on the highway or does it also happen at certain rpm ranges at lower speeds? You can use sport mode to test that.

[diponyou]

That's what I said. I argued for a little while telling him to just pump it out and the foreman said no dice. Looks like I'll be doing it myself and saving some money.

Seems to only happen when the ac is on at higher speeds.
I can test it out once I get the car back from the dealer.

[Brucelinc]

From many dealers perspective, the PTU lube change is never "due."  Dealers in my area will not do it as a routine maintenance item, either.

Regarding your situation only when the A/C is on:  Obviously, the A/C puts a little more drag on the engine.  Are you sure it is not the compressor engaging and disengaging?  It could be low on refrigerant. 

[SHOdded]

Be sure your PCM calibration is up to date as well.  Spark plugs would be my first guess also, though.

[diponyou]

Update v2
Got the car back after the re-flash on the ecu and holy hell what a difference. It feels like the replaced the transmission. The up shifts are perfect, firm but smooth at the same time. Before the down shifts were slow and kinda clunky. Now they are smooth and on point.

I got on it while on the highway with ac on and no sign of any shuttering. Did the same in a safe area while going about 20 and it was perfect.

Not sure if it's just placebo but the car just feels much more tight with both shifting and throttle response.

Besides them not doing the PTU I am very happy.
Not to mention that I just got the email that my torrie tune, 3bar map and 170 tstat just shipped.

[SHOnUup]

Great to hear. Has to settle the thoughts a bit. Cmon package now!!!