2003 Mustang GT with Vortech Supercharger.


New Member
Jul 16, 2023
Good morning

So I have a 2003 Mustang GT with a Vortech Supercharger. I bought it new in 2003 and did a ton of upgrades to it. In 2009 it had to go into ford because it stopped running. they claimed the ECM had failed and put in a new one. It had run but always seemed a little different than before it failed but I kind of shruggged it off at the time. In 2011 I bought a new car but kept the Mustang. A few months later my daughters boyfriend really wanted to buy the car from me so I worked something out. He was making payments to me however unfortunately him and my daughter broke up and he failed to pay off the last part of the deal so I ended up keeping the car. However while he had it he changed out the throttle body with a BBK unit and took the car to a dyno tuner. They apparently had difficulty tuning the car claiming there was something not right and couldn't figure it out. He had provided them with an SCT X4 for a custom tune to be uploaded with. This was all in like 2014. So the car has been sitting in storage since that point in time. Fast forward to today. I took off the BBK throttle body to get the engine back to the way it was before I sold it. The car starts and idles great with no chip in it. The SCT X4 is not married to the car so I assume that the stock tune is in place in the ECM. And I don't see a custom tune in the X4 to apply. I have 2 different SCT chips, one was the one provided when I installed the vortech supercharger which always got by ok before however I wanted it to be better so I had taken the car in 2004 to Dynolabs in San Ramon and they dyno tuned it for me and put the tune on an SCT red chip. If I plug in the SCT red chip that was dyno tuned the car starts and idles well but after about 15-20 minutes at idle the car dies and will start for a few seconds and then die and then will stop starting. As soon as I remove the red chip the car starts right up. So I assume the red chip may be bad. If I plug in the original chip that I got from when I bought the vortech kit the car starts, and stays running but idles super rich.

So if there any way I can tell if the stock tune is in play on the ECM? I'm trying to get the car ready to sell but don't want to invest a ton into it. Unfortunately in California I have to smog it. Any other ideas. The car only has 102k miles on it and other than some clear coat issues is a great car.
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