2004 Mustang GT issues after bolt-ons added

[Leo090]

Hi everyone, I have a 2004 Mustang GT, 4.6, AUTOMATIC, it has 142k miles on it. It ran just fine , never any issues and I wanted a little more power, so I added some bolt-ons - A
-SR performance cold air intake
-SR performance 70mm throttle body
-SR perfomance plenum
-SR perfomance intake spacer.

I have minimal mechanical knowledge and this was the first time I ever did anything with an engine. I could not get the old TPS off and used a new one from a reputable aftermarket website.

My issues are as follows, rough idle, and sometimes surging.
Then when I drive, I definatley feel more power , but my car doesn't want to shift into 5th gear (or whatever the next gear is on an automatic.) It will shift at a much higher rpm point (3,500) then previously prior to adding the mods. Sometimes it doesn't shift at that point but when it does it finally gives a strong kick / jerk and shifts. After the car warms up, this issue becomes worse as the vehicle struggles to get over 20mph.

I tried getting a tune, I purchased a BAMA X4 and programmed a basic custom 89 octane performance tune. Did not fix issue at all.

What could be my issue, Please help. I wanted to make my car better and practically ruined it .

 

[jay99914]

I'd say make sure you plugged everything back in correctly such as MAF and everything else that goes to the throttle body. You could also have a vacume leak from the spacer/TB. Did you torque correctly, and use new gaskets?

 

[89ripper]

I agree, spacers especially can create a leak. I would check there first

 

[Leo090]

I agree, spacers especially can create a leak. I would check there first

But would a spacer vacuum really cause a vehicle to not shift gears propertly upon accelleration? I used a smoke machine, although not in the best way and didnt see any leaks in the tb or plenum. I wil ltry again with an improved method. I tried tightening down the plenum , which did not help my issue. Could a poorly placed or voltaged TPS cause these issues as well?

 

[89ripper]

What trans are you running? Im assuming most of it is electronically controlled. Your symptoms reminded me of vacuum leaks with regard to your idle issue. I run a spacer on mine and it took me a bit to get right. I did skim over that part about your tps. If its anything like the foxbody, you just need to make sure its not out of range. Sorry im not well versed on that for your particular year.

 

[Leo090]

What trans are you running? Im assuming most of it is electronically controlled. Your symptoms reminded me of vacuum leaks with regard to your idle issue. I run a spacer on mine and it took me a bit to get right. I did skim over that part about your tps. If its anything like the foxbody, you just need to make sure its not out of range. Sorry im not well versed on that for your particular year.

Its the stock auto trans that came with my 2004 mustang gt v8, 4.6.

 

[89ripper]

Do you recall when the transmission issues started? Before or after your intake mods?

 

[Leo090]

Do you recall when the transmission issues started? Before or after your intake mods?

100% occurred after the mods, I havent been able to drive the car after my mods. It is just too dangerous and I dont want to risk burning the transmission. also, I must add, the issue gets worst once the car warms up fully.

 

[89ripper]

Gotcha. Just good to know where to start troubleshooting...odd that it was driving fine before that. Can you post a pic of your engine/throttle body setup?

 

[Leo090]

Gotcha. Just good to know where to start troubleshooting...odd that it was driving fine before that. Can you post a pic of your engine/throttle body setup?

PLEASE DISREGARD THE DETACH MAF SENSOR, the pic was taken prior to attaching it.

 

[Leo090]

Gotcha. Just good to know where to start troubleshooting...odd that it was driving fine before that. Can you post a pic of your engine/throttle body setup?

Also, with these SR performance throttle bodies, it comes with a small little black circle grommet to place in the hole where the tps goes. Is this necassary? and could that be causing the issues?

 

[89ripper]

To answer your question, im not 100% sure. I would be curious what would happen if you returned everything to stock. Also if you havent pulled codes i would be interested in that as well considering your trans which could be a separate issue you are dealing with.

 

[Leo090]

To answer your question, im not 100% sure. I would be curious what would happen if you returned everything to stock. Also if you havent pulled codes i would be interested in that as well considering your trans which could be a separate issue you are dealing with.

There is no check engine light.

 

[89ripper]

Doesnt necessarily mean anything. Just part of the process in troubleshooting your car.

 

[Leo090]

Doesnt necessarily mean anything. Just part of the process in troubleshooting your car.

So there may still be codes? ok Ill do an OBD scan in the next day or two and let you know if I get anything

 

[89ripper]

Its possible Leo. These pcm/ecus can act funny with mods sometimes. It would be worth a check. By then someone else might be able to chime in....im only slightly familiar with your particular year.

 

[Leo090]

Its possible Leo. These pcm/ecus can act funny with mods sometimes. It would be worth a check. By then someone else might be able to chime in....im only slightly familiar with your particular year.

I had my mechanic friend remove the original TPS from the original throttle body and I attached it to the new throttle body. It fixed my shifting issue for the first 20 minutes (the car shifted exactly where it needed to), however after the car warmed up the vehicle did not want to shift at all, I had to drive home at 15 mph . My mechanic friend suggested I go revert back to stock part by part and testing the car along the way, if fully stock and I still have this isssue he recommends getting a new transmission. It is just weird that I never had this problem until I decided to add all these bolt-ons. Also, did OBD scan,,, no codes after this last failed test drive. It seems I fixed my tps issue, but still transmission doesnt shift when vehicle gets warm.

 

[Noobz347]

I would suggest [not] buying a new trans. Find a good trans shop in your area. For the money of a new trans, you can get yours rebuilt and [improved] at the same time.

Also: Has the TV cable and mounting points been thoroughly inspected?

 

[Leo090]

Where would I find the TV cable on a 2004 mustang gt?

 

[Noobz347]

Where would I find the TV cable on a 2004 mustang gt?

My mistake... 2004 has electronic shift control.

Can you tell I'm a Fox guy?