Post Reply 
 
Thread Rating:
  • 0 Votes - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5
07 Colorado rough idle
09-15-2014, 09:08 PM
Post: #1
07 Colorado rough idle
I have been having rough idle troubles with my 07 Colorado. Recently got flash code P1400. Started when braking, RPMs would drop to around 500 - 700 and once stopped would settle at around 900 idling fairly rough. I have cleaned the throttle body and changed the plugs with a little improvement to RPM but still having a rough idle and what feels like a misfire. My guess is either vacuum leak or in the coil packs but not certain as to my next steps. also where to find all my vacuum lines to check. Thanks for any help in advance. Also running much louder now sounding like an after market exhaust on acceleration. not sure if this is just the CAT burning off excess fuel.

Already tried:
Cleaned throttle body and changed sparks plugs. Also has a new air filter and can see no blockages.

Forever missing my 78 Camaro, things where so much simpler then.
Find all posts by this user
Quote this message in a reply
09-15-2014, 10:11 PM
Post: #2
RE: 07 Colorado rough idle
This code typically means there's an issue with vac leaks or someone has replaced the air filter with a non-stock unit. These engines are rather fickle in that department so I am told. Same goes for aftermarket spark plugs. If there are no other codes then you can forget about looking for new coil packs or similar. If they fail or if there's really a misfire that will set it's own code. Random misfire and single misfire have different codes too so you can pick them out. Either of these must happen for at least 10 seconds and after the engine is warm to set a code.

Here's what I would do... You say you have cleaned the throttle body but did you do a good cleaning of the IAC? (Idle Air Control) It's that small passage just in front of the throttle plate and it allows a controlled amount of air to pass as the ECM dictates. The internal works get gummy and hang up, which may cause your odd idle condition. Clean that up (2-3 times to be sure) and try again.

Also, these engines are fickle about the fuel they use. Stick with "regular" because it burns better. Run a tank or two and see how it goes before looking into possible vac leaks on the manifold gaskets. (if you still have issues)

Oh, the actual meaning of that code has to do with cold start / fast warm up systems. If the stuff I just pointed out isn't right you can get a false code.
Find all posts by this user
Quote this message in a reply
09-16-2014, 01:54 PM
Post: #3
RE: 07 Colorado rough idle
Could you possibly send some visual help so I know what I'm looking for. Thank you

Forever missing my 78 Camaro, things where so much simpler then.
Find all posts by this user
Quote this message in a reply
09-16-2014, 08:49 PM
Post: #4
RE: 07 Colorado rough idle
I just cleaned the MAF sensor as well. I've been having trouble finding information on where exactly the IAC is for an 07 Colorado if this model even has one. Cleaning the MAF sensor seems to have helped a good deal at first glance and that pesky light finally went off. Still it feels like there is still something amiss. Do I need to disconnect the battery to let the computer reset or would that be pointless?

Forever missing my 78 Camaro, things where so much simpler then.
Find all posts by this user
Quote this message in a reply
09-16-2014, 09:17 PM (This post was last modified: 09-16-2014 09:21 PM by Rupe.)
Post: #5
RE: 07 Colorado rough idle
Here's a couple of short videos, generic in nature but good advice, especially if you have "drive by wire" and not a throttle cable. The first one shows the throttle body removed from the car but you probably don't have to do that. The second one is showing what I was trying to explain, cleaning the IAC while on the car. The port is in different locations depending on the car but they all do the same thing and are right in front of the throttle plate. If you poke around YouTube you can find more details on exactly how the IAC works but I didn't find any specifically for your vehicle.

https://www.youtube.com/watch?v=XrcaDh4xDLs

https://www.youtube.com/watch?v=i82s4ZfR2js

Edited to add: disconnecting the battery will not help anything and may cause the engine to run slighty rough till it goes through a complete cold / hot cycle. Best thing to do is attempt these fixes then take a trip to someone with a scanner who can clear the codes. Drive it for a few days and see if everything is ok. If the light comes back on then anything in memory will be a fresh problem and you can post the codes here for more discussion.
Find all posts by this user
Quote this message in a reply
Post Reply 


Forum Jump:


User(s) browsing this thread: 1 Guest(s)