Alright y'all,
I've been scratching my head over this one for a while now. I am the proud owner of a (mostly) stock 1996 XJ. I bought it with 164k miles just a couple months ago and so far have just done regular periodic maintenance and I just finished installing a 4" rocklink long arm lift. Here's the thing that's got me stumped though: The entire time I've had it, it's idled around 1100-1200 rpm. I thought "vacuum leak, no problem..." Couldn't find one anywhere. TPS sweeps from 13.7% - ~80% from no throttle to full throttle. Calculated TPS based on manifold pressure tracks with this. A couple of times I've noticed at a stop sign that the idle is down where it should be, somewhere below 1000, but that's few and far between. Just today I had the thought of pulling up a "tach" on my Torque app, and low and behold it reads ~750 - 780 rpm pretty consistently. I look at the dash and boom, 1200 rpm again.... What gives? All the dash gauges function, I haven't noticed anything weird. The ECU and the tach both take input from the same thing right? I would imagine CPS or cam position based on the distributor. Anybody dealt with this before?
I've been scratching my head over this one for a while now. I am the proud owner of a (mostly) stock 1996 XJ. I bought it with 164k miles just a couple months ago and so far have just done regular periodic maintenance and I just finished installing a 4" rocklink long arm lift. Here's the thing that's got me stumped though: The entire time I've had it, it's idled around 1100-1200 rpm. I thought "vacuum leak, no problem..." Couldn't find one anywhere. TPS sweeps from 13.7% - ~80% from no throttle to full throttle. Calculated TPS based on manifold pressure tracks with this. A couple of times I've noticed at a stop sign that the idle is down where it should be, somewhere below 1000, but that's few and far between. Just today I had the thought of pulling up a "tach" on my Torque app, and low and behold it reads ~750 - 780 rpm pretty consistently. I look at the dash and boom, 1200 rpm again.... What gives? All the dash gauges function, I haven't noticed anything weird. The ECU and the tach both take input from the same thing right? I would imagine CPS or cam position based on the distributor. Anybody dealt with this before?