When I got the XJ both hoses from the valve cover to the intake and the airbox were trash. I had this yellow hose laying around and thought I would use it. When I put it on the rear of tge valve cover and hooked it to the motor, the engine idled down and ran rough for a couple seconds then ran good (decent, see next paragraph) again. Could I plug that intake port and plug the valve cover port or put a filter on it?

Next, the motor runs a little rough on idle but great on acceleration. (When I say rough, I mean a little rougher rhan smooth.) I checked the plugs and they all look good, a light brown. Could tge injectors be clogged? I put some sea foam in the tank and it ran so smooth I had to check the RPM gauge to make sure it was running, then the next day it was running rough again.

Help on both of these would be great. Thanks.

 

Sorry for the sideways pic. It loaded that way. Didn't take the pic that way. It would be the TOP hose now. Lol

 

As long as your yellow hoses are snug and aren't leaking they should be fine.
I wouldn't block it off.

As far as the rough idle, I've been battling the same issue. First thing to try is to clean your throttle body and Idle Air Controller. That works for some. Didn't work for me. Some people have had some success with putting seafoam in their throttle body (slowly!). Others say changing out the pre cat O2 sensors (didn't work for me).

Now that hot weather is here my AC Is on almost all the time and the AC keeps my idle much smoother (higher) so I don't really notice is as much.

 

Well I was just thinking, when I put sea foam in the tank, the engine runs smooth. The sea foam doesn't touch the TB, it goes right to the injectors and into the engine. So wouldn't that rule out the TB? I also might try a different gas station this weekend and see if that helps. Something without ethenol mix.

 

The hoses you replaced are the PCV or CCV hoses. I don't know which term is right but I recently had to replace mine.

 

Need to run half a can threw the throttle body and clean sensor or valve before you do it.

 

Well after runnin it with the new hoses yesterday for bout an hour on the way home, it was runnin smooth this mornin. But something else I noticed was my temp gauge. When I throttle up, the temp gauge goes down and when I let off it goes back up to normal. And it does this quickly, not slow. And also when at idle, it goes down to the first mark and is jumpy.

 

Probably need a new temp sensor or a wire is loose.

 

While on break I unplugged what I thought was the temp sensor in the thermostat housing. The gauge didn't move. All it did was turn on the check engine light. Where would the temp sensor be?

 

That's the temp sensor.

 

Any clue qhy the gauge didn't move? It was running at operating temp. Shouldn't it have went to zero?

 

Did you remove it while the engine was running?

 

Yes.

 

Thats probably why the gauge stuck where it was at, the ecu no longer got a signal so it gave you the cel.

 

A new sensor will run you about $25. Wrap the threads with teflon tape and don't torque it in too much or the probe will bottom out and crack and possibly leak.