I just bought my first wrangler, 1999 with the 2.5l engine and a stick. I have a question about an issue and would appreciate any help.
The jeep has 112K on it, so I replaced the water pump and the thermostat since the pump was just starting to leak. I got everything back together and started it and heard a very loud, very large vacuum leak. The source of this is the throttle body (something I didn't touch or get near) and there is a port on the side that has a 90 degree rubber tube on it that looks like a spark plug boot. The bottom of the tube is wide open to the atmosphere and it sucks in a huge amount of vacuum. There are at least three such ports there, this is the upper one. I assumed I had knocked off a vacuum hose that was supposed to go into this boot but I sure can't see one anywhere. If I plug this port the jeep runs fine. There are no codes either.
Was this a factory plug for an unused vacuum port? (For an automatic transmission, maybe?) And maybe the right angle rubber boot used to have a plug in it and that fell out?
I did notice a couple days before I did this work that the idle suddenly went to 3000 rpm and stayed there on a cold start. I shut it off and it was fine after that.
Many thanks in advance.