[DEBEST]

2003 MUSTANG GT
OK, first off, I am a new member and I am extremely glad to be a part of this website. Enough said, now on the my problem.
When the car is first started (cold) it does not have this problem, only once the car had reached operating temperature will the problems start.
Again this only happens in first and second gear (once warmed up). If I'm at approx 2000rpm's and floor it, it feels like the car loses 2/3 of its power, its still accelerating but at an extreme loss of power, 2nd gear is identically the same. However if I gradually wind the engine to 4500rpm's and THEN floor it, there is absolutely no hesitation (in both 1st and 2nd). So if I wind 1st gear up to 4500, then floor it and snatch 2nd, it will run like a raped ape unless my rpm's fall under 4500 when shifting into 2nd.
I can shift early into 3rd gear (1500rpm's or so) and floor it and there is no hesitation.
Its really hard to tear out of the hole when you can't gag 1st or 2nd gear. All mods on the car were done before I got it.
My local performance shop said I need a tuner and custom tune, but he answered the question alittle too fast and for 600 dollars I would like a second oppinion. Also, CEL is not on.
Again this is my first post, so please be gentle and ask for any info that I forgot to post. Thank you in advance for all your time and help.

My Car:
MAC CAI
Underdrive Pulleys
70mm BBK Powerplus TB
3.73 gears

 

[03silverMustang]

you most likely do need a tune. it will get rid of any bogging and also give you a decent amount of hp and tq boost.

 

[wmburns]

Is the MAF clean? Use only products made for the job.

What are the IAT readings? Are they reasonable for the outside air temperature?

I would also be interested to know the IAT readings when the motor is hot. For example, is the IAT sensor being heat soaked? This could be causing the PCM to pull timing.

This can also be crossed checked by looking at the timing advance. Compare the timing at similar RPMs. An ODB2 scanner is very helpful.

The other cause of poor power is excessive EGR flow.

Recommend starting by inspecting the vacuum lines to/from the DPFE sensor.

Next move on to the EGR valve. One quick test is to disconnect and plug the EGR vacuum line to see if there is any improvement. Note, the test is not conclusive if the EGR valve itself is leaking/not fully closing.

What are the results of a compression test?

I'm assuming this is a manual transmission. FWIIW, it's not reasonable to expect the motor to make the same torque at 2k that it does at 4k. Everybody has different expectations but on my own car, it pulls much harder from 4k than it does from 2k.

 

[DEBEST]

Please forgive my ignorance, but how do I find out my IAT readings ? A dyno ? I called American Muscle and they said it sounds like a timing advance problem, but may be as simple as a partially clogged EGR.
What does it mean for the IAT sensor to be heat soaked. Again please forgive my ignorance. Thank You.

Only attempts I have made was to clean my MAF sensor and replace my fuel filter. I do realize the torque curve would be higher around the 4k range, but I can actually feel the power get cut back if I dump the throttle. The car has more power at 1/2 throttle than WOT in 1st and 2nd.

Yes its a manual transmission. And dont think I'm missing a cylinder, cause 3rd and 4th will hold you back in the seat.

 

[wmburns]

The easiest way to find out IAT (Input Air Temperature) is with an ODB2 scanner that can monitor operational data.

An ODB2 reader usually only reads DTC codes.

To say a sensor is "heat soaked" means that it has absorbed heat from the surounding area and it's reading is incorrect because of the heat soak.

The OEM's make many intake parts out of plastic to reduce the effect of heat soaking.

The PCM will alter timing depending upon how hot the input air temperature is. So can you see how an elevated IAT reading can reduce performance?

Do you have an open air filter? This could be a source of hot engine bay air that is raising the IAT readings.

I need you to bear with me for a moment. On a manual transmission Mustang there are no electronics to interface with the transmission. What this means is the PCM has no way of knowning what gear the transmission is in.

This very different for the automatic. The PCM is in direct control of what gear is selected.

What does this mean? For a manaul application, the PCM can not take any special action that depends upon a SPECIFIC gear.

So....IF there is a difference in performance between 1&2 and 3&4, it has to be because of factors such as RPM, engine load, and throttle position.

 

[DEBEST]

Maybe another dumb question/statement on my part, but does it matter that my ABS light is on and my traction control doesnt work (push the TC button as much as I want and it never lights up, yet I can rev the engine and dump the clutch and burn out all day long.) Ford said that the button should light up and I should get a picture of a car and squiggly line under it...but I dont.

 

[wmburns]

Traction contol relies on ABS to work. Therefore, if ABS is broken, then traction control is broken as well.

No ABS=No traction control

IMO, the ABS problem is not related to the loss of power because traction control is not operational.

 

[drifter18533434]

sounds like your timing is goofy--Geta tune and that should fix it

 

[AMChrisRose]

I don't think getting a tune will fix the underlying issue. There's no doubt that any 96-12 Mustang needs a good custom tune, and will benefit. However, in this case, I'd take a look at some other things.

Make sure to clean the throttle body and MAF sensors. I'd also replace your fuel filter, so that it's not an octane degrading issue. Make sure that you're filling up with good fuel from a reputable Sunoco, Shell, etc. Don't fill up at a convenience store like Sheetz, Wawa, 711 or whatever. Give that a shot, because it sounds octane related to me.

New fuel filter (cheap), new plugs (fairly cheap), clean MAF and clean throttle body, use the best gas out there, 90% of the time you'll find your issue. Could be condensation in the gas tank. Try running through a good fuel injector cleaner.

How many miles on the car?

I also agree with wmburns, the TCS/ABS problem is a second issue.

Hope this helps! Luckily, this stuff is all cheap, so knocking this stuff out of the way can be done for under $100 and may make the car feel like new!

After it's fixed: GET A BAMA CUSTOM TUNE! You'll find even more power!

 

[DEBEST]

thanks for the input guys. Might be a week or 2 before I can come up with 600 extra bucks for a SCT x3 tuner and dyno run. but I will post my results when any are found. I will also check the post daily for any more comments/suggestions. Thank you all so much for your time.

 

[AMChrisRose]

600 bucks!?!? :nono:

379.99 with free shipping and free tunes for life from Bama. On top of that, a dyno run should be between 50-100 dollars in your area just to check out tunes. And our tunes are going to be proven tunes on thousands of Mustangs just like yours. Give the Bama team a call at the number/hours in my signature for more info. We're the largest SCT dealer in the world.

As for the tuner, it's worth it - but I still think you need to fix the underlying problem, which is definitely there.

 

[drifter18533434]

well, ok Chris--your the expert--But instead of spending
abunch of money on a tuner, just hav the engine timing checked. Onlycertain RPM's areactingup..Try theleast expensive way first


NDETC..

 

[mustangsvt281]

well, ok Chris--your the expert--But instead of spending
abunch of money on a tuner, just hav the engine timing checked. Onlycertain RPM's areactingup..Try theleast expensive way first


NDETC..

or get the tuner and benefit either way, and also be able to datalog what is going on with your motor. that will also help diagnose the problem.