I'm working on a 2003 4.6L Mustang with a vortech charger. After the tune it ran perfect. It cam back with a melted plug, no other damage to the engine thankfuly. I installed a wideband 02, and the afr is 14.7:1 at idle, and goes as high as 17 on the meter, plus I hear detonation. fuel presure is at 40 psi. any ideas,

Thanks in advance for any help.

 

Under what conditions (load, throttle position, rpm, gear, etc.)?

 

Did you upgrade injectors? You may be at the limit of their capacity, at given psi.

I do know that the same injectors will deliver more if you can raise fuel pressure, but you will need to revisit your tune.

 

the idle a/f is fine but the 17 is scary if thats under throttle...pump pressure might be alittle high for idle...but we need alittle more info man

 

The idle A/F really wont hurt anything its the underload number that can be scary, my wideband fluctuates between 14-17 at idle.