tetrad
NAXJA Forum User
- Location
- Hesperia, CA
My 99 XJ started having intermittent surging at idle and power loss on acceleration. The surging at idle was rhythmic at about 1 cycle per second, which made me think one of my O2 sensors might be giving a bad signal. And the power loss on acceleration felt a lot like a problem that was fixed with new O2 sensors a couple of years ago.
I unplugged the upstream O2 sensor, and took a few short trips (with the engine already hot). The problem seems to be gone: I don't have any hesitation on acceleration and I haven't had any more surging at idle. Also, normally when my AC compressor cycles my RPMs bump up by about 250 and the Jeep will often overcome the brakes and start moving forward if I'm not really stepping on them. That seems to be completely gone -- with or without AC I'm pegged at 750 idle.
The Jeep just passed CA smog a few weeks ago, so the O2 sensor couldn't have totally failed (?).
Does this sound like an O2 sensor? If not, what else could it be? I also considered that my TPS might have a dead spot, but I replaced it within the last few years with a dealer part. The last time I had my exhaust manifold in my hands, there was a bit of a crack at the collector. Could that, or a bad mating between the exhaust or intake manifolds and the head, be giving the O2 sensor a bad reading?
I unplugged the upstream O2 sensor, and took a few short trips (with the engine already hot). The problem seems to be gone: I don't have any hesitation on acceleration and I haven't had any more surging at idle. Also, normally when my AC compressor cycles my RPMs bump up by about 250 and the Jeep will often overcome the brakes and start moving forward if I'm not really stepping on them. That seems to be completely gone -- with or without AC I'm pegged at 750 idle.
The Jeep just passed CA smog a few weeks ago, so the O2 sensor couldn't have totally failed (?).
Does this sound like an O2 sensor? If not, what else could it be? I also considered that my TPS might have a dead spot, but I replaced it within the last few years with a dealer part. The last time I had my exhaust manifold in my hands, there was a bit of a crack at the collector. Could that, or a bad mating between the exhaust or intake manifolds and the head, be giving the O2 sensor a bad reading?