I have a 2008 Scion tC. about a week ago it started to idle real rough. Its so rough it actually rattle my exhaust. I also have real bad valve chatter.
Anyone have any ideas about what could be wrong? Mods done to the motor are:

HPS short ram intake
Alpha Werks Header
Megan racing mid-pipe
Skunk2 Cat-Back exhaust
Greddy Emanage Blue

If anyone has any ideas please help me out. I hate my baby running like this.

 

bent valves? have you miss shifted?

 

idk but it might be something that you can see physically too....ummm check your vacuum hoses for splits

 

mmm I have the same too. Almost sounds like a chattery motor mount, but when i popped my hood to check it sounds like its coming from the valve train. It dose not do it all the time which is weird because i figured if it were the valves it would do it all the time right?

 

i have the same problem, ive also notice if my car is uphill it makes the noise but downhill it doesnt, my car like to idle rough every couple of months and when driving itll bog but i figure its my maf sensor going bad so i always just reset ecu and im good to go =]......GHETTO WAY AT FIXING A PROBLEM=WIN

 

ok stupid question but why are you using the Emanage blue........and the 08 computer I thought relearns its tune if you change it........not sure 100% onthat but it is possible.

check your vacume lines and your EGR valve on the back of the valve cover,it may be loose..........

other than that toyotas have noisy valve tranes......and if you have AC on it will shake a bit and get louder.

could also be you damaged the MAF installing the CAI.......coupler loose on the CAI,man there are a lot of things that could be wrong.

 

yea the other day i tigthemed my egr and my brake booster line because thats where my vacuum block is taped into and it fixed my problems....as far as noise...its not the usual valve train chik chik chik its a chik chik chik..click chik click click chik its kind alike a beat...but then when given more rpms is dissapears and also ac being on eliminates the noise

 

mine is a actual chatter from what sounds like my exhaust valves. I'm going to take off the header and see if anythings bent this week. The chatter comes and goes at idle in 5-10 sec incraments off and on. I wish i member the post but another had some bent valves and was hearing a clicking sound. I have 16k miles on my motor thou

 

you gotta take out that huge stage 3 cam you got.

i notice in camry's the motor is very shaky. check your oil. maybe next oil change throw in a qt of lucas?

 

idk, The timing was checked before the car was started and it ran fine and quite till now. It almost sounds like a belt chatter but its coming from my exhaust manifold. And you can hear it from outside of the car with the hood closed. I hate driving around and my car squeaking at red lights. lol When i pop the header off i'll know for sure

 

i'm actually having the same problem as the OP.
its been like over 4 months or so since i've noticed the rough idle.
i didn't think to much about it, but after scanning the forums.
i thought i should ask for some help.
i have similar mods as the OP.

Injen CAI
Alphawerks Header
Full Skunk2 Exhaust w/ a 24in Magnaflow Resonator

i'm thinking about reseting the ECU.

any thoughts?

 

yeah check al the things I listed as they seem to be the most comman causes for shaking idle.

bent valves could be cause of chatter,even worn cam could do it,timing chain stretched......cars are a pain at times.....lol

o2 sensor on the header could be wearing out or damaged too......that is a spendy pain there.

 

well i'm using an automatic trans.
and i've only had the for about 22k miles.
so i don't think worn cams, timing belt, and valves could be the problem
lol, even if they were i don't even know how to get to those parts on my car.

my o2 sensor was replaced like a month ago, i bought it from someone from SL.
so, i doubt thats the issue too. lol, maybe i'm a little to trusting in used parts?

i did get T-Boned sometime in November.
maybe its a faulty motor mount?

who knows i should get my mechanic to take a look at it.

 

check the o2 sensor and make sure it is not loose,also could be a motor mount......