Hey guys, 100400k miles 2005 6MT;

My car's been idling rough at red lights, and sometimes will drop RPMs and sound like it's bogging down. It'll sometimes also shut off, even when my foot is still on the clutch.

The idle will usually hover around 7-800rpm, then dip below 5 before bouncing back up. But once it dips it definitely sounds like I'm going to stall, despite being in neutral. Any idea what the cause is?

 

Oh and no codes, which makes it impossible (at least for me) to diagnose

 

Clogged/bad EGR valve is my guess.

 

Coil packs were the source of my misfire, but the RPM never dipped like that and the car never died.

Plugs and EGR are also good places to start looking.

 

fuel pump?

 

Is your A/C running? How's the battery and its ground?

 

I don't think it's the fuel pump; doesn't happen when the RPMs are high. Would EGR issue not throw a code?

Battery is 1 year old, ground is tight and the positive cable was replaced within the last half year as well

 

EGR is inactive (fully closed) at idle.

 

I had this happen before it was a carbon deposit holding open egr valve. Funny enough I had this happen again today the exact symptoms you said. I think it was the same problem but this time the carbon must have dislodged itself because it stopped dipping after 10 minutes. It takes two nuts and 10 min to open the egr up and see if a carbon rock is holding your valve open.

 

It may take some time for the code to appear.
My TL had the rough low idle issue for 3-4 days of daily driving before the CEL appeared due to a bad EGR valve.

 

Brought it to the family mechanic, said he didn't think there were issues with the EGR. He did say that the intake and exhaust valves needed to be adjusted though; after I got the car back there hasn't been any issue. I bought a standard motor EGR valve off amazon anyway for $60, figure if the problem starts rearing it's head again I'll just change the whole thing.

 

I see you have it fixed but I had similar issues with the car wanting to stall at a red light. It ended up being my A/C compressor taking a dump on me. once it was wasted the car acted normal. replaced the compressor and no issue since.

 

Interesting...did you do the replacement yourself?

 

No, had my mechanic do it. Parts/Labor = $550 OTD

 

check your EGR and make sure its clean, if its still there then check the main relay.