Blackbox19

I am looking at getting a 05 Gt. Its got CAI and 4.10 gears and automatic. Owner says only thing done to computer is a tuner used to change the CAI and gears and the 20 inch rims and tires.. Not sure if he screwed with shift points, but he said he did not.. as the tuner he had did not give that option.. I have not verified it.

It drives fine at 70 and when at lower speeds than 45.

But when I took it on the interstate as I eased into it to get up to speed I noticed the car seemed to hesitate or stubble or maybe the trans was searching for the right gear or the torque converter was locking or unlocking.. But it was differently not normal feeling.

Is this something to be concerned with..? Car in great shape and low miles 78k..

And in my budget FOR NOW.... Dont want to get a money pit.. I would have rather it been a 5 or 6 spd... BUT for the money and what what I doing with it the auto will be just fine.

Blackbox19

stumble...... Not sure why my spell checker let that stubble fly...
And I can not edit yet soo.,......

Blackbox19

no one?

Derf00

I'm assuming it's an Auto? Try this, turn off overdrive by hitting the button on the right of the shifter (nearest your pinky). You'll know it's off when it the little O/D Off light turns on in the dash by the guages.

Now try driving around and duplicating the problem. If the problem goes away then you most likely have a failing Overdrive Servo. A common issue on the 5R55S/W transmission used in mustangs and trucks and you are around the right mileage for it show up.

Also, do you have records of when the tranny fluid was flushed? It's supposed to be done every 30K miles. Some people stick to the manuals 100K but, let's be honest, if you drive it daily and /or during the summer, it automatically falls under severe duty which is every 30K.

Blackbox19

Thanks for that info.. I will give all that a try and do you know where to get the RIGHT fluid to do the change? I am aware of the way it gets put in and how to get the right amount in there also. Just not what type is the right kind.. So much changes day to month on what fluid works.

JimC

Fixed it for you - Mod Power needed to fix a title!

Blackbox19

Ok.... the guy pulled the TUNE out of it...
Alll that was left was the 20" rims and the CAI...
Did not do it at all this time... SO thank god for that.

I wish I got a manual./././/////

Auto is no fun except in slow traffic and stop and go town driving....

I may get use to it, but I forsee me selling this one and getting a 5 spd or 6 spd from a 11......... 5.0..
Cause I test drove a 5.0 and this one and the 5.0 was BRUTAL compared...
And the 06 has 4.11 gears and the 5.0 had the stock 3.55.................
This is my first modern mustang... So.

Derf00

Mercon V only. It can be found at your local ford dealer or Castrol through Autozone. I'm really hesitant to ever use one of those multi-ATF type fluids especially if you're only doing a drain and refill of what's in the tranny.

Dropping the pan and replacing the filter will require about 6 quarts. Given that you don't know when the last time the tranny was serviced I might suggest a flush from the dealer as it will replace ALL the fluid, not just what's in the tranny. There is no Drain on the Torque Converter and you will have fluid in the cooler and lines that you won't get with a drain/refill.

Why did you have the tune taken out of it? Was that the cause of your hesitation/stumble? Personally, I've found the stock tune to be really laggy in the shifting area and throttle tip-in (throttle lag when you first take off) so I would never go back to it.

JimC

It isn't the automatic that is the problem. The d!ck who put the car back to the stock tune, then traded it in while leaving mods that require a tune on the car; that is the problem. You need to get a tune for the CAI and gears. The computer is trying to adjust but is getting bad information because of the mods. Speed will be off so the transmission isn't going to shift anywhere near properly.

Never understood those d!cks who cheap out and keep the tuner saying "it won't be my problem" when they trade the car in.

Blackbox19

He left the updates to the computer for the CAI and Rims... Just pulled out the performance tune part I guess.. I have not screwed with it any... Its a hypertech or something like that..

Yeah the throttle response is not as good as it was with the tune in there... BUT the stumble has gone away... So I had to know if that was it or not...
Not sure what parameters the tun changed but I think the shift points need cleared up some cause around 55-60 area and climbing it stumbled a little... Never after that tho and not at cruising speed of 74..

Found a 2011 5.0 6 spd that guy wants to trade me... SO may just have found my out on the suckomatic.