1997 zj 4.0l bought with 160k miles,now has 274k plus.been solid.until now.started off with two codes,po132 and po740.replaced the up stream 02 sensor still had the light did re scan and came up with po171 and the old girl drinks gas like it grows on trees.my question would be what have other people found to be causing this in the real world?any insight would be great.

 

First of all, I wouldn't worry about the P0740 Torque converter clutch. Mine hasn't worked in 3 years and the only difference it makes is about 200 rpm at 70 mph. I've already replaced the solenoid so if it's the clutch itself, I'm NOT pulling the converter out just for that.

You may have some bad injectors. Those old Siemens are junk to begin with and 2 of mine cracked at about 190K miles. I replaced mine with 4-hole Bosch for about $140 for reconditioned ones.