96 XJ sputters/jumps/bucks but doesn't die
 

On my way home last week, my 1996 XJ (186,000 miles) started jumping/stuttering which I could physically feel while driving.
What it's doing is hard to describe, but you could also hear a change in the way the vehicle sounds while it's happening.

I had a 30 minute drive back home and despite intermittently (almost every few seconds) doing this the entire way back, I didn't lose any power, it never stalled or died.


I have no check engine light or other warning lights on.


This has me completely stumped.

1. Check your transmission fluid quantity and quality

If that is where it should be, I would next suspect the fuel pump. It really could be a lot of things, but the fuel pump is likely to begin failing without throwing any codes. Other contenders would be a failing crankshaft position sensor, o2 sensor, MAP, or throttle position sensor.

The more details you provide, the more someone might be able to help you narrow it down just a little. Here are some questions:

1. Did you get the impression it was shifting gears?
2. What speed did this happen at?
3. Have there been any other transmission/shifting related weirdness lately?
4. Any changes in start-up time/cranks when you turn the key recently?

Transmission fluid is good and I actually changed the fuel pump a few months back.

To answer your questions:
1. Yes, I believe it is shifting gears.
2. The issue occurs at any speed.
3. No other trans/shifting issues.
4. I have not had any issues starting it up at all.


I'm also thinking it could be a failing sensor. Figuring out which one before I just start buying and changing them is a whole other issue.

Thanks for your advice! Really appreciate it.

To be extra sure you mean what I think. You are saying that you believe when the problem occurs that the vehicle is shifting gears in that moment. Right?