i recently began to have a rough idle and the tech at the dealership said the spark plugs needed changed. so i just changed the plugs and the rough idle happens more often and it now idles at 500 rpms, was around 700 or a little higher before i changed the plugs. the plugs i used are the oem (stock) ngk plugs and they were gapped at .041 so i left them at that. i checked the air filter and it is fairly clean. anyone have any ideas what is wrong before i venture back to the dealership for another 2 hours and get told they can't find any problem? the car has 20000 miles by the way. Thanks.

 

Mine does that same thing if I'm sitting at drive through, I just tap the gas and it jumps to 2k then it goes down to normal idle

 

Install a grounding kit. I never had what I would call "rough" idle, but I never had nice smooth idle until I installed my grounding kit. It was a DIY job and I used 4ga wire and all gold connectors. Read over this thread:

https://www.evolutionm.net/forums/sh...threadid=30385

Even though thats for Evos you should get the basic idea. I just laid out the cable, cut, crimped the connectors (and with 4ga, that ain't easy) and screwed in. You do have to get an terminal adapter like for an amp for the negative battery post. It took me about 2 hours to do, but would go shorter if you had the cable pre-made. Somebdy in the post says they make kits for like $40. I would post pics, but I don't have a digital camera. Hell, I don't even have a cell phone.

EDIT: P.S. I have a manual, but I don't think it would be different for an automatic.

 

did u try resetting the ECU yet?

 

bad gas?
water in your gas?
clump of something in your fuel fliter?

 

Man, I am having the EXACT same problem and it is freaking me out pretty bad. I really don't want to go to the dealership because it costs me at least $100 every time I go there no matter what the problem seems to be. My CEL came on yesterday. My car was running at a higher than normal idle(10-12k) for the last week, up until I changed my plugs and now I have NO idle speed it seems. Twice it didn't even kick before the engine killed. It just went down the powerband after I revved and then the engine died immediately. A few times it struggled but dies shortly after. My CEL is still on also. I have reset my ECU and put the old plugs back in to see if that was the problem. No luck still. Does anyone have a real idea about what the problem could be???

 

sounds like a problem I had.. I had to get some injector cleaner, and also a new tank of gas seemed to be my problem.. if you have sheets i suggest u never go there crappy gas.
After that my problem was fixed..then i began the world of problems with turbo

 

Your injectors should not be dirty or clogged on a 1-2 y/o car unless you have some seriously high mileage.

I had a similar issue when my car was NA. It really only happened after I changed to Denso iridium spark plugs. The car never stalled or anything so I didn't bother fixing it, but it does seem possible that it's electrical/ground related. I had similar problems after my car was turbocharged as well, but so many variables made it even more difficult to diagnose.

 

i wonder if he got it fixed?

 

I have this same problem and it drives my freakin nuts. I dont know if its due to the cold weather or what but ill be sitting at a stop light, and my car will random give little shakes. does it in neutral and drive...i have 6500 miles, never put any fuel injector cleaner in and running on my stock plugs....what do you guys suggest? Bad gas? Upgrade the plugs and wires? Clean my injectors? Any help is appreciated!!

 

I had the same problem and noticed that my throttle cable had loosened up and had way too much slack, so I moved the positioner and took out the slack and that took care of it.

 

how would i go about doin that bro...whats the positioner look like and do i just like unclip it from the throttle cable, pull the slack out and reclip it or something?? I have no idea how it works

 

I'd bet on bad gas first including water in the gas etc... If you are getting a CEL that means you are more than likely seeing poor emissions or fuel problems 90% of the time... Try and dump in some good quality gas from a good shop. Throw in some higher octane fuel just in case what is actually happening is your car is stumbling as it is trying to fight what it thinks may be knock. The ECU can do that to a certain extent... mixing in some higher octane can help that (will not give you any more hp, or mpg or anything so don't think that!)

 

earth your engine for better idle and throttle responce.