Ok for thoes that rember i rebuilt the motor in my sidekick , about 2k miles ago, still runs great and has max compression all the way around,  but i have a knock comming from inside the intake, i listened to it with a stethiscope,  not from the motor itself but from inside the throtlebody, and smetimes when you are sitting at a light it will rev up to about 2500, and then drop to 900, and then rev up to 2500 and drop to 900 but when you start to accelerate you have no problembs, and sometimes it will do it at the next light sometimes not,    it does not burn oil, or smoke,  runs realllly well.

I am thinking of running a supercharger, and want to get the knock in the intake and the idel thing take care of before i bolt one on.

Whoa

     Theres one I haven't heard before...you are sure the knock is in the intake?

The idling up and down is not uncommon...hunting...IMO one of two things typically.
- Vacuum leak
- Something causing the engine to go rich at idle

Vacuum leak
- Check all hoses, connections, EGR, all the gaskets and anything that connects to the
  intake. Check, Check and Recheck....most cases it's a vacuum leak with that symptom.

Rich at idle
- Could be a sensor (Coolant, O2 or other)
- Check for codes, when it's doing it. (Yeah I know, never does it when you want)

There is a very long shot......could your cam timing be out? I can sometimes give this type of symptom.....but it's a real long shot.

Those are my best guesses

The knock in the intake I've never run into....but man find out whats wrong before making any more changes..........or you'll be ssssoooorrrrrry!

Zag

Ok for thoes that rember i rebuilt the motor in my sidekick , about 2k miles ago, still runs great and has max compression all the way around,  but i have a knock comming from inside the intake, i listened to it with a stethiscope,  not from the motor itself but from inside the throtlebody, and smetimes when you are sitting at a light it will rev up to about 2500, and then drop to 900, and then rev up to 2500 and drop to 900 but when you start to accelerate you have no problembs, and sometimes it will do it at the next light sometimes not,    it does not burn oil, or smoke,  runs realllly well.

I am thinking of running a supercharger, and want to get the knock in the intake and the idel thing take care of before i bolt one on.

What year is your Sidekick? Here's a common problem with the earlier FI systems. What happens is that they have an "idle up" that when any accessory is on (head lights, heater, etc...) the system idles the engine  up and the injectors are obnoxiously loud. The air box does a good job of quieting this down but if you have that off and have a gauze filter or nothing you'll really hear it.

The second deal with the huge swings in the idle can be caused by the TPS (throttle position sensor) being out of adjustment [refer to FSM for adjustment] and/or if the MAP (manifold air pressure) sensor is faulty. Since it is intermittant, I'd first check you vacuum lines to the MAP sensor... they maybe cracked or streched really far and broken if you have a body lift.

-Eric

The 'Throttle Up valve' is located on the back of the throttle body and opens the butterfly a little. If the noise is irregular it could be this that you can hear, otherwise I think Eric is right and its the injector you can hear. There is also an Idle Speed controller on the throttle body, its worth checking the vacuum pipes to this and to the EGR valve. It might also be worth pulling the EGR valve off the end of the manifold as these can get coked up. The TPS also has a switch built in to tell the ECU that the motor is at idle. The FSM is a very good investment, it has around 120 pages devoted to the Fuel Injection system.

Thankyou verry much, and yes i know that the knocking sound is in the TB part, no nois from the oil pan, and only the verry slight  tick tick tick on the valve cove with a stethiscpoe, now you put the thing at the base of the TB and CLATTER CLATTER CLATTER, but no noise any were else, cam timeing, not beyond posible but not likely new timing belt, and timing light says every things is perfect, and it does not miss, or sputter at all and when it is warm and not  verrying the idel  it idels right at about 850 rpm  smoth as can be and will run smooth all the way to redline,   the exhaust leak is anoying but ill fix that when i go 2.5 all the way back.

and it does not miss while the idel is jumping and going down, and only really does it if the lights radi or heater is on.

EEEEExxxxcccceeellleeennnttt... more information

     From your last post I think Eric's diagnosis is the winner, check out that idle up issue.

Zag