Weird growling/burping/farting noise

92 4.0
It usually happens:
Only after start up, when I start moving.
Warm or cold.
Only going forward.
For just a fraction of a second.

Doesn't seem to be related to turning.

It doesn't affect performance, it's just weird.

Has anyone else noticed this or does my XJ have gastrointestinal issues?uke:

Leave the wife and/or the dog home and take it for another test drive.

The clutch fan make a loud noise during startup and goes away shortly.

Also, the engine is in retard (ignition) for the first 30 to 60 seconds to warm up the cats.

Try to wait that long before driving off.

What year is the XJ?

It could be the HVAC doors moving around (vacuum actuated). It's sometimes more noticeable when you have a vacuum line leak and the doors move to default.
Is the noise coming from under the dash or up front under the hood.
The power steering pump is often noisey until it warms up a bit. New power steering fluid often seems to help some. Power steering fluid does get thinner over the years from shear.

Thanks for the input.

It's coming from under the hood, I can feel a very slight vibration in the steering wheel when it happens.

If I just sit and idle, nothing happens, so I don't think it's the fan.
It is related to just when I start moving forward, maybe at 5mph.
And it's just the first time I move forward after starting the engine.

BTW:
I have never heard my wife fart in the decade+ I have known her, strange huh?
(I, on the other hand, fart enough for the both of us)
Our dogs are debarked.

Is it auto tranny or manual? What size engine?

92 auto 4.0

i could be way off here, but sounds like it could be a brake hanging up a little. do you usually set the parking brake? if the rear drums are out of adjustment they could be over expanding when you use the brakes or ebrake and they will not release when you come to a complete stop like that. my 94 d35 used to do it a lot when the brakes were out and my 87 does it now too every now and then. 94 has disc rear now =D just a thought, could even be a front caliper perhaps but less likely