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2001 Jeep wrangler Engine runs rough

the engine was running rough when it hit 2K RPM only. above and below it is fine. replaced the injectors/O2 sensor and it ran well for a couple of months but it is doing it again. when engine hits 2K rpm it will sputter and run rough. engine light gives me code 171 engine running rich or lean. dont know what else to look at.

Did you change the fuel filter when you changed the injectors?

Replacing the injectors and O2 sensor and seeing immediate improvement is a big clue. I’d guess either you have got some bad gas, or a faulty fuel filter, and the injectors clogged up again, or there’s something that’s damaging your O2 sensor. Is the engine burning much oil? Any abnormal looking smoke coming out the exhaust? Did you use any RTV (silicone rubber) sealants during recent engine repairs?

maybe the fuel filter, I will check that out. engine does not burn oil, no smoke. i didn’t use any RTV sealant other than the anti sieze on the exaust manifold when i replaced that. but i did that months before the injectors/O2 sensor. The 2K RPM only though has me confused. is it possible to have an O2 sensor go bad so quickly?

What engine is installed in your Jeep? 4cylinder or 6 ?? The 6 is the old Rambler 242 (4L) relic…You might try tightening all the intake manifold bolts and studs as these can loosen and cause vacuum leaks, destroying the idle…Also, a malfunctioning EGR valve can cause the kind of problems you describe…

Inspect the cam position sensor shaft housing, check the hold down clamp for signs of movment. These shafts have been known to bind, the housing will rotate sending the cam/crank signals out of sync. Performace problems are most noted @ 2,000 RPMs, the transition from low speed to high speed adaptive fuel cell occurs @ 1,984 RPMs on a JTEC controler.

Caddyman, It has the 4 cylinder. no EGR valve. it idles great, just the loping at 2K RPM
Thanks Nevada545, that is much appreciated to try and solve the 2K riddle.

If it was a cam sensor malfunction, it’s hard to understand why replacing the O2 sensors and injectors would have helped. But that might have been a coincidence.

Ignore that, I was refering to the 4.0L engine. The 2.5L has a conventinal distributor. But at least we solved the mistory of how many cylinders your wrangler has.