so two new issues i have been noticing lately...

one is when starting up first thing in the morning or after it has been sitting for a while over night or so, i get the waterfall sound in the dash, now before you all go jumping to tell me its my heater core(i thought this too initially), i have not lost any coolant, i am up, the over flow is up, and i do not over heat. the carpet on the passenger side is dry, always is, there are no visual indicators outside of the vehicle under the truck that i am leaking any coolant. after it warms up to operating temps its fine, no more running water sound. at first i thought this was just simply the drains from the sun roof, but it has done this several times with out it raining for several days in a row, so i know its not from that. also my heater works fine, blows hot, both front and back, and never had an issue with the cooling system. i have tried burping the system but it just simply wont take any more...

issue number two, again start it up first thing in the morning and it runs rough, like ive got a bad plug or injector, but i get no codes, nothing is triggered or stored. with in about 30-90 sec this clears up and it runs fine. my last tune up was about 30k ago so im almost thinking its time to replace some plugs on this thing again. -i run 92 in it almost all the time, will go through a tank of gas every 3-4 days so i know its not just a bad batch of gas, have a brand new air filter, and clean MAFS fuel filter was changes about 30k ago as well

any thoughts or ideas guys?

Before I'd rule out a air pocket in the heater core I'd recommend a few things...

How are you filling the coolant? simply adding to the radiator and overflow like any normal dude would?

It is quite possible to get a very difficult to burp air pocket trapped in the top of the heater core and not be able to fill anymore.
Because the heater core is higher up than the radiator you need to in some circumstances create a higher point for the air to go by either back filling at the heater hoses themselves or using what I prefer. something like this...
Lisle 24610 Spill-Free Funnel : Amazon.com : Automotive

With that contraption on it you can fill it and run the vehicle with the heat on which will circulate the coolant and any air pockets would find there way to the new highest point which now would be out of the sealed funnel dooohickey.

worth a shot before getting too crazy anywhooo.


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The rough idle:

Do you have a scan tool capable of reading fuel trims and/or specific cylinder misfire data?

I know its a long shot but it's pretty much a guessing game without being able to see that data in the morning when its going on. It may eventually store a code though.

i might have to give that or something like that a try...

any thoughts on the rough idle at cold start?

i have noticed no loss in power or MPG so im kinda thinking its not a plug or wire issue or injector issue...

Kid,

I don't know if you have looked at the IAC but I had one on an Acura go south on me on could starts due to a connection inside the solenoid plunger. If it has never been cleaned, it may be worth a shot.

What kind of reading for RPMs, Volts, etc are you getting on these cold starts?

i have not had a chance to look at volts ect, the problem does not last long enough for me to check, by the time i pop the hood and open it its done. RPMs are normal and the tac shows no sign of rough idle(needle holds steady at normal range 600-750).

i can pull the IAC off and take a look see at it, maybe clean it..."? anything youd recommend to use or not use? i have some MAFS cleaner or electromotive cleaner.....

I usually just use a Carb cleaner that is O2 senor safe since the 4runner is not the only auto I deal with. I'd find the electrical specs on how to test it per the FSM and see if it meets the requirements.

Find an app that can be downloaded to see live data if you can.

I am apt to agree with Kyle that sooner rather than later you will see a code, maybe an injector, but don't want to put the cart before the horse per se.

That rough first start thing seems like over fueling. When was the last time you ran a injector cleaner through it? Like techtron. Unless you have a chevron gas station to go to.

When you remove the rad cap its up to the neck. Correct? It should be.

With the heater on you should be able to do a few hard accelerations to redline when the engine is fully up to temp and push that air pocket to the rad. From their if your expansion hose is sealed correctly at the filler neck and no cracks or holes in the hose it should make it to the expansion tank over a few heat cycles. Your tank level should increase 1/4 to 3/8 inch between a cold engine and a fully hot engine. (Fully hot means you can't squeeze the upper rad hose and see the fluid level shake around in the expansion tank)

If you remove the rad cap and its full to to tippy top...........may be you want to get your coolant tested for combustion gasses. It may be the beginning of a bad head gasket.