My 02 Disco 2 has a sudden power loss and rpms start jumping when in between 3k and 4k, and im not entirely sure whats causing. I just recently replaced cylinder head gaskets and the intake manifold gasket and it seemed fine for a bit until this issue popped up out of nowhere. I cant seem to locate the issue as ive tried checking for vacuum leaks, cleaning the throttle body, replacing sensors, etc. Its somewhat on and off but its mainly a constant issue with small breaks of maybe an hour. Any idea whats causing this?

 

Any codes?

Does sound like a vacuum leak. Pull spark plugs and look at them, they will also gove more info. I had an intake on a dodge one time and the vacuum leak was internal, pulling air (and oil) from the valley. Would be very strange, but if all else fails may be something to look into.

I'd want to see some codes and live sensor data.

 

I shoulda mentioned it in the post but there's no codes, at all. That's part of the reason I'm having such a hard time diagnosing it. Ill check out the spark plugs tomorrow as well and see if I cant get some live data. Thanks for the suggestion!

 

If no vacuum leaks, check iac valve and clean it

 

Also, what are you using to check for vacuum leaks? If it's brake clean, I have used brake clean that didn't show anything. I recommend starting fluid to be sure.

I personally doubt IAC because of the missing - IAC air would still be metered and should just idle at the wrong speed without missing. Doesn't hurt to clean though.