Scion tC Forums banner
1 - 6 of 6 Posts

·
Registered
Joined
·
3 Posts
Discussion Starter · #1 ·
Hey guys! my 2011 TC has a rough idle when I come to a stop and rpms sometimes drop below 500 and shakes the car a bit. I bought it in April with 87k miles on it. I changed the spark plugs a few months ago and have cleaned the throttle body and MAF sensor twice. the spray cleaning seams to help the situation but ultimately would come back after a few days. So far it hasn't tripped up a check engine light so I don't know what it could be. I was thinking about taking it to a mechanic so they can run through the live data to diagnose the issue but I'm pretty cheap living in NY where I don't feel like being scammed by a dishonest mechanic lol. I've read it could be a bad PCV valve, O2 sensor, or MAF sensor but before I decide, Id love to get some advice from yawl. The problem seams common enough but cant find a consistent fix. Id really appreciate the help. THANKS! :)
 

·
Registered
Joined
·
1 Posts
I have been through the gamut on my 2011 that I recently bought for the same problem. New MAF, super cleaned top to bottom TB, new plugs, new OEM coil packs, new air filter, new PCV, ran through some Lucas FI cleaner last tank....reset....ALL to no avail...... I wish I could find a fix for this.
 

·
Registered
2007 Scion TC 2.4L automatic
Joined
·
62 Posts
Check the 10amp fuse in the engine fuse/relay box. I can't remember if it's labeled aic/iac.

Check the age & condition of the PVC, rubber hoses, alternator, battery, ignition coil packs, ignition coil wires/pig tail harnesses, battery cables, corrosion, looseness, dirty filthy gunked up throttle body, gas cap, level of gas, fuel pressure, fuel pump,

To bench test ignition coils:
Start the car & let it warm up.
Leave in park e brake on.
Open the hood & while the engine is running, gently unplug the wire harness/pigtail on each ignition coil & listen/pay attention to the rpms.
If the rpms doesn't drop when the ignition coil wire is removed, consider that spark plug ignition coil bad.

To verify, turn off vehicle & switch the "bad" ignition coil to another cylinder, restart & bench test again. If the same happens from the "bad" coil, then that coil is bad.

This is a quick way to find out if not able to get to a mechanic, OBD2 scanner, trusted garage & or last resort your local Toyota stealership.

Hope this helps
 
1 - 6 of 6 Posts
Top