Whats up? I have a sweet '91 RS. It has a 305,TBI,auto and T-tops. It only has 19K on it, but I want more go!! I dont want to totaly gut everything so I installed a HyperTech ThermoMaster chip, a 180 deg. stat, a fan switch and low restriction exhaust. But when I'm cruzin' down the interstate my check engine lite comes on. It also dropped my shift points about 400 RPM. I drink gas like its going out of style. What the heck is going on? Anyone got any ideas?

 

I have an idea, its the chip!!!

i have the same chip in my l98 and it does the exact same thing, the check engine light should be a lean at cruise code which is 13 and its running overly rich on the freeway because it thinks the motor is lean.

 

I have an idea, its the chip!!!

i have the same chip in my l98 and it does the exact same thing, the check engine light should be a lean at cruise code which is 13 and its running overly rich on the freeway because it thinks the motor is lean.

 

I had the same thing with my LB9, and the stock chip. I just bumped up the fuel pressure, and no more engine light!