Well yea i was sitting in my blazer the other morning before school. and i felt it starting to shake like it was gonna stall. So i did the standard stuff checked the gauges and made sure it was in park (its an automatic btw) When i looked at the RPM's it was only running at 400. thats four hundred! now normaly just sitting still in park its at 600. is this something i should be worried about or should i just leave it alone?

 

So you were sitting in it with it in park. Was it hot out and was the A/C on? It is possible that the IAC valve is gummed up and took a little bit to compensate for an increased load on the engine. When the A/C kicks on, the IAC valve is supposed to open up more to slightly increase the idle. If it were gummed up, it would be difficult for it to make the fine adjustments quick enough.

Maybe try removing the throttlebody and giving everything a good cleaning (passages and all).

 

it was like between 55-60 outside with no a/c or heat or anything running. I'm really not sure on this kinda stuff. im more on the aftermarket stuff. I'll open the throttle body up sometime this week should i just like use a wet rag or do i need a certain thing to clean that? also if this low idle continues could it damage my engine?

 

Worse it would do is stall. I guess it may be possible that your engine fan locked up to cool the radiator down (it's thermostatically controlled by the air temp going through the radiator) and that caused the same scenario as I laid out previously...

To properly clean the TB, it really must be removed. Clean with sensor safe carb cleaner (throttle body cleaner) and possibly an old toothbrush for the IAC passages. The tb isn't all that difficult to remove, just a 10mm socket and something like a 6" extension. You'll need a torx bit to remove the IAC valve to clean it and it's bore.

I do suppose that it is possible that you could have a bad tank of gas that makes the addition of load to the engine more noticeable, but that's a stretch. A can of dry-gas will take care of that. I run a bottle of dry-cas through my vehicles every other tank in the winter time, and every oil change they get a bottle of Chevron w/ Techron fuel injector cleaner.

 

Could be a vacuum leak as well?

 

I have no clue wut that is. I know im such a noob on this stuff sorry lol. but how would i fix that stuff?

 

To fix a vacuum leak you would have to find it first. Could be as simple as a hose fell off the fitting, or as difficult to find as a leak in the intake manifold gasket. There are several methods to find vacuum leaks.

Every vehicle has a vacuum diagram in the engine compartment, find it and trace all hoses. If they are cracked, hard, brittle, borken, etc. Replace them. Most auto parts stores will gladely sell you hose by the foot. Measure it and take a hunk of the old hose with you to get the right size.

If that failed to find the leak. Try the mechanics sthescope (sp). Use a pice of hose. stick one end by your ear and move the other end around the engine compartment, carfell of hot parts and moving parts. Or buy a mech stehtescope and use it.

Still haven't found it. Spray ether around the hoses, engine compartment. If the idle goes up, you found the area of the leak, now you just need to pin-point it. Ether can explode, so use it with care. We use it off-roading to seat tire beads. Spray a mist inside the tire and toss in a match. The ether explodes and seats the tire on the bead. I have also seen it blow the tire completely past the bead, and that was a 44" tire. Make on hell of a loud explosion and draws in the neighbors, especially in a campground next to the off-road park. If I new how to post video, I would show you want I mean.

 

If you don't want to be playing with highly flammable liquids like ether you could use a little bit of water in a spray bottle with the engine at operating temperature spray water around where the hoses attatch or where you suspect a gasket to be leaking, depending on the size and location of the leak you'll hear the idle either smooth out or get really rough. A little water getting sucked into the air intake won't hurt the engine any, one forum I visit occasionally has a thread several pages long where members argue that cleaning the combustion chamber with water (that's right pouring water slowly into a vaccum line) is as effective as using seafoam. Personally I use Seafoam for cleaning the combustion chamber and water or carb cleaner for checking vaccum lines, whichever is easiest to grab at the moment. My dad used to use anything from wd-40 to rubbing alcohol before we learned that certain chemicals can break down rubber hoses and gaskets.