Topic: misfire under load

[Steve2002TJ]

I installed my Stage 1 chip on my 2002 Jeep Wrangler 2.5 4-cylinder and it's made driving much easier. However, I'm getting what appears to be a misfire when climbing mountain roads under full throttle between 4,000 and 5,000 rpm. My TJ has approx. 36,000 miles on it and it's received routine servicing from my mechanic. I run premium fuel with a  K&N filter, but otherwise the motor is stock. Any ideas?

[yellowta]

You need to run a higher octane gas. The chip has your timing advanced too far, and it is causing detonation. The higher the octane, the higher the resistance to detonation. With the minor miss you are describing, it shouldn't take much to correct. Try running the mid grade gas instead of the regular and see if it helps.    

[Bounty Hunter]

I run premium fuel with a  K&N filter, but otherwise the motor is stock. Any ideas?

[Jeffy]

So if you take the chip out does it still have timing issues?

[yellowta]

I run premium fuel with a  K&N filter, but otherwise the motor is stock. Any ideas?

Oops, well guess you could also check your plugs.... mine had a nasty little miss under heavy load when my gap was too large