Hey guys so i have a 2002 mustang gt i picked up recently with no cats, long tube headers, no o2 sensors, flowmaster 10’s, a jlt cai, 70mm throttle intake, smaller cams, larger injectors and has 70k miles. You can definitely smell the gas when it is cranked, and im not sure what the easiest way to find out how to see if it was tuned to run rich. Could getting a 78mm throttle intake help with getting more air in? I want to leave the cams alone, but dont mind downgrading to smaller injectors. Also, is it not good to run the engine rich as it is? One final question, would it be better in terms of cost to try the throttle intake or focus on engine afr tuning?
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New Member
Aug 11, 2020
Kansas City, MO
I have a similarish setup in a 02 GT and I have a Diablo custom tune. I have been using the “race” tune for about 4 years (they give you 3 tunes) and it runs pretty rich accompanied with plenty of fuel smell. I’m not an engineer but she runs pretty strong and at 122000 and still shredding clutches. You must have a tune current on the car or I doubt if it would run with your upgrades. It may be an aggressive tune, I’m would look into a less aggressive tune if the fuel smell is unacceptable.
The only negative I understand to an excessive rich condition, besides fouling plugs, is that the excess fuel washes lube out of cylinders.... ??


5 Year Member
Apr 16, 2015
Do you have a tune or is it running off the stock computer? I would think any computer or tune would need the O2 sensors for it to run right. Not having them would easily explain running rich.