Disconnecting sensors
 

Hi CF,

I'm having an intermittent power loss issue with my xj that has gotten pretty bad this past few days, it feels like it's stalling, can be quite jerky, like it's fighting for fuel, air, or something. I suspect it's electrical as the issue is intermittent, but there's a number of issues it could be. I'm wanting to test if it's a sensor issue before moving on to other possibilities.

I'm not a mechanic by any modicum of imagination's stretch - is there any reason why I couldn't unplug one sensor at a time, drive the truck around, to see if the power loss issue goes away? Would this help pinpoint a particular bad sensor causing my problem? For example, could I unplug my TPS and drive it around to test if the power loss problem goes away? If so, which sensors could I do this to and still have it drive, and is there any sensor I couldn't do this with? I realise removing a sensor will cause the engine to maybe run rich/funny, but my thinking was if the power loss goes away, maybe that's a culprit sensor.

Thank you advance for the help.

(Cherokee XJ, 1999, 4.0 petrol, 5sp manual)

You would be a lot better served to get an elm327 for a few dollars, put it in your OBDII port, load the Torque app on your phone and read the sensor data in real time. You can make graphs as well as guages which would make a sensor drop out really plain to see. If you had a pre 96 things would be harder to deal with.

Thanks, doublechaz, I have an obd2 scanner, but it's a basic one, mostly just for reading codes. Obviously not really helping in my current issue. I've ordered an elm327, as you suggest, and I'll give it a play around. My idea with disconnecting sensors was - in theory, could it work to diagnose if one of them was the problem issue. I'm not a mechanic/electrician, but I do like to learn and work through stuff myself as opposed to bringing it to a shop.

If you're not getting any codes set and it's worse after warming up, I would put money on a failing crank position sensor.

Most of the sensors you could unplug and still have the engine run, won't cause an intermittent stumble like you described.