My '90 XJ is running like a fine Swiss watch but I have noticed one thing that puzzles me a little. I would love the thoughts from some of the experts out there. I should clarify that I implemented all of Cruiser54's recommendations and I doubt that there is a '90 XJ in existence with better grounds than this one.
The issue appears as a high idle immediately after start but this doesn't seem to be the same as previous threads because I can completely eliminate the issue if I simply leave the key in the "on" position for 4-5 seconds before I crank it. If I turn the key immediately to the crank position, it will fire right up but I will often see the idle jump to over 2000 rpm and will then want to settle down around 1200 rpm (in Park) and will idle at 800-850ish in Drive. If I show a little patience and wait the 4-5 seconds in the on position, it fires up and the idle drops almost immediately to 800 rpm and it will idle nicely around 450-500rpm in drive.
I am starting to think this is normal because it works like this every time. It is almost as if the reset of the IAC gets interrupted with the quick crank and it considers that wherever it stopped must be base setting. On the other hand, if i give it enough time to fully reset, it happily runs at a proper idle.
Thoughts? Is this normal or should I start looking for a fix?
I should add that when I restored this old girl a couple of years ago, I did a complete clean up of the throttle body so I know that there is no buildup in the IAC area.
The issue appears as a high idle immediately after start but this doesn't seem to be the same as previous threads because I can completely eliminate the issue if I simply leave the key in the "on" position for 4-5 seconds before I crank it. If I turn the key immediately to the crank position, it will fire right up but I will often see the idle jump to over 2000 rpm and will then want to settle down around 1200 rpm (in Park) and will idle at 800-850ish in Drive. If I show a little patience and wait the 4-5 seconds in the on position, it fires up and the idle drops almost immediately to 800 rpm and it will idle nicely around 450-500rpm in drive.
I am starting to think this is normal because it works like this every time. It is almost as if the reset of the IAC gets interrupted with the quick crank and it considers that wherever it stopped must be base setting. On the other hand, if i give it enough time to fully reset, it happily runs at a proper idle.
Thoughts? Is this normal or should I start looking for a fix?
I should add that when I restored this old girl a couple of years ago, I did a complete clean up of the throttle body so I know that there is no buildup in the IAC area.