Ok so i just bought this 2000 Eclipse GT and it looks all fine and nice, but when im driving around and i have to stop at a red light for more than 10 sec the RPMs start to like jump but not high, it barely makes it to 1, but its enough that you can feel the car sort of jump.. idk what it is and i cant really figure it out.. if anyone else is having this problem or anyone knows what it is and how to fix it please tell.. thanks

Also if anyone could tell me how or what could make my muffler rattle, it sounds like a nail or a screw is in there, but idk..

For your idle it could be any number of different things. But does it rev up and back down then back up and back down until you start moving or does it just rev up and stay there til you keep moving?

And for your exhaust it could be as simple as you have a hangar loose that is rattling around or you could actually have something in your exhaust.

when im stopped, it just goes up to 1000 rpms and drops back to half, then jumps again, and again.. several times till i start driving..

how much would it cost to fix my muffler if its a lose hanger..?

If its an auto it might be your torque converter starting to lock up.

but whats funny now, i just got done sitting in my car and in park the RPMs starting going from half of one, to like 1 and a half.. and then drops to 0 and kicks back up to one again.. its kinda scary

idle control is messed up, i dont know if we have a whole unit with valves and sensors that control it or its the ECU. The throttle positioning sensor could also be messed up or simply the air sensor keeps sending wrong signals of how much oxygen there is in air which makes the injectors inject more or less fuel. Anyway, clean it the Mass airflow sensor, its connected to you air intake, its the square part with cables on it. get the cleaner for it, dont put water there.

The MAF, Idle speed controller, or like previously stated, the torque converter of an automatic transmission.

It's not expensive for a hangar, Id say no more than $25 or $30 to weld one back on, unless they have to put a new hangar on, which if that's the case it should still be under $50. Take it to any local mechanic and have them check the hangars, if it is a loose hangar, they'll simply weld it back on and it's fixed. If it's not that just have them check the entire exhaust system.

alright well ill try all that and see what happens.

thanks

Thats very similar to what happens when you disconnect your mass airflow sensor. dirty or defective sensor most likely

Do you have the AC on?

Yeh Mounts?
Get Prothane inserts if so.
Easy to replace as long as u got a floor jack and winch.(hacksaw to cut the remaining of stock mount insert)
Prothane mounts dont need grease or Pressing.
So yeh.
Like 60-80 bucks.
FYI-if this is the problem watch out for the studs on the tranny mount they like to go up when releasing.(took me 30 mins to fix them :-/)

ya well if i turn the AC on it does start to act funny too.. but also when i drive without the AC on it does it... the AC turned on makes it do it alot more... now the Tach will fall down to 0 and the car shuts off.. i could be at a stop light and it just turns off.. the check engine light came on the other day.. so idk

TPS or the ICS

went to get it checked and it was the MAF, Idle Air, and Random Misfiring of Cylinders.. so its going to cost like 1 grand to fix it all..