MReesePT

I recently updated my 2003 Mustang GT Convertible with a 2006 Mustang GT convertible but have a problem that seems to be getting worse. I am a Newbie to this forum and need some advice, please.

When I test drove the car the first time it seemed to lack acceleration from 3000-5000 rpm's, but the more I drove it, this seemed to go away. I dismissed it as the car hadnt been driven in a while and bought the car.

Now that I have about 1000 miles on the car I am loosing significant acceleration. This loss was intermittant at first, but now it happens every time I drive it after the first time through the gears.

To explain further.... I start the car up and take off with great power the first time through the gears, but after that, it is very sluggish from 3000-5000 rpms not having that "kick" of acceleration. If I stop and shut the car off, start it right back up, it then has the power that it had initially but only for the first cycle through the gears. This is very frustrating because I can see how much power the car should have and it will not run that way all the time.

My car is a 2006 GT with 85,000 miles with all stock equipement. I have changed the plugs, cleaned the mass air flow sensor, cleaned the TB, reset the gas pedal all as described in this forum with no success. I am planning on gettting a CAI and tune but I would like to get it running "back to normal" before modifying and improving.

I would appreciate your thoughts. Thanks

Menace

There are TSBs out for faulty fuel pumps. Typically lack of acceleration after extended trips, and I had to have mine replaced. Since you are well beyond the warranty range I'm not sure if Ford will cover this. It might be worth looking into though.

JDWalton

on a side note, its hot as ***** out in our area right now, it could just be heat soak currently. Sounds like you did all the normal things I would think of. You changed the plugs yourself? I would reseat the COPs just for piece of mind.

i would go ahead and get the tuner and CAI combo anyway. Not only will you see a power gain but the software to data log is not hard to set up, if you get a SC3 combo from brenspeed you can even capture the data log and see if they can help you troubleshoot.

Things that would be useful for you now would be:
Maf voltage
Fuel pump duty cycle
actual fuel pump voltage
fuel rail psi
TPS position
Throw in RPM

You get a data log with something like those paramaters and it can tell a whole lot about your car without having to bring it anywhere. you just need the tuner, a usb cable, and a laptop.


Also, if you get a tuner like that through brenspeed, seeing as your out of warranty anyway, if it turns out to be fuel pump, its not that hard to throw a GT500 fuel pump at it while your in there, and have brenspeed send you a updated tune for that. Future proof your car you know?

Goldenpony

Have you checked for trouble codes?

MReesePT

I have not checked for any codes. (I am not that good, but no engine light on)

What has me confused... is the fact that the car not running right (not rough but just lacks that "punch"), I can shut it off along side the road, start it back up and it runs like a champ but for only one time through the gears. If I stop and punch it again, it then runs like a sluggish dog again. It almost seems like it is being held back at 3000 rpm and something is not opening up. Even when it is running bad it will go to 5000 but very slow from 3000-5000 while when it is running good, it snaps you back in your seat between 3-5000.

I am not much of a mechanic and I just cannot figure out why it runs great one time and then not the next.

I have not changed the fuel filter any thoughts on that being the problem?

I did change the plugs myself with one piece Champions (thanks to the other posts), but I did not change the coil packs. Could the coil packs sound like the problem?

Thanks for all of your thoughts.

Nuke

The fuel pump issue/TSB mentioned above has symptoms of significant hesitation/bogging under hard acceleration AFTER steady state cruising; it's not what you seem to describe.

Other than recommending you reset the Adaptive learning (battery disconnect for 20-30 minutes), I can only concur with the possibility of heat soak. I'd also do some other typical PM items in addition to those that you've already done such as fuel filter replacement and run a can of SeaFoam thru the tank once or twice. My only other thoughts are clogged cats but I'm not sure that they'd flow cold and then plug-up hot.

Menace

Despite him not doing any extended periods of driving, these are the EXACT symptoms I had before I took it in and they replaced the fuel pump. I wouldn't ward it off just because you don't have the EXACT symptoms, but it's your choice.

MReesePT

No help!!! (I have changed plugs, cleaned TB and MAS)

I changed the fuel filter, a little dirty but no help to the performance

I reset the pedal, no help

I also just got a Steeda CAI with tuner. I tried the tuner with a 93 tune without any improvement. I dont want to instal the CAI until I figure out what is wrong.

Also No Codes according to my X3 tuner

Just using a stopwatch when my car is running "good" vs "bad" it is 2 seconds slower to 60mph. It has no zip from3-5000 rpms. Most times runs better if I shut if off then start again or if I dont punch it from a start but rather go a little then punch it.

I am leaning towards the fuel pump but not throwing any codes

ANY THOUGHTS??? Help!!!!

I dont know who to even take it to, a stealership??

Nuke

Unfortumately, I think a dealership might be your best option unless you find a shop that knows Stangs inside out. Anyone else would just be guessing.

JDWalton

is the 93 tune, a 93 tune written for the steeda intake you got? Its a different MAF size so I would assume so and NEEDS to be installed as that tune is calibrated to the much larger maf size. With the smaller diameter stock tube, the velocity through the intake is much higher, and the maf being calibrated for the larger diameter tube, with that velocity through it, is going to be telling your computer your getting significantly more air then it is. As a result will pump significantly more fuel, and run rich, making very little power.

Install the intake and the tune that is for it, download the software to monitor what I told you from SCT, and if your still having problems, send the data log to your tuner.