Here's the problem.. I have a 98 tj 4.0 that I've been battling with a hesitation above 2k mostly noticeable in third gear. A year ago threw a code #1 cyl misfire. 158k miles so I started inquiring what could cause this. I quickly found out that only a thousand things could do this. Here we go.. I've replaced exhaust front to rear with magnaflow high flow cat and muff. New 02 sensors, clockspring, all sensors on throttle body, and fuel pump. Bit the bullet and pulled the head. Aha.. burnt valve#1 cyl. Replaced the head with atk from 4wparts. Upon setting engine to TDC noticed that at TDC Rotor on distributor was about 8 deg from directly at #1 on cap. Could this b my problem with hesitation. Can this advance make it run rich to the point of burning valves?
04-25-2013 04:02 PM
Weak valve springs were a common problem in '97-98 4.0L engines which could cause a burned valve or valve seat. Since the the engine timing is totally under control of the engine computer, I doubt what you saw would/could have caused the burned valve.
04-25-2013 08:06 PM
Thanks jerry. Actually it was one of your posts I read that helped me diagnose the weak valve springs. New head is working well. I appreciate the input. I just wanted to cover all the angles after putting in so much blood sweat and tears. Welcome to owning a Jeep.. right;)