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Author Topic: Help with diagnosing a misfire problem  (Read 3149 times)
Bub
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Posts: 1405

#13 STC Chevy Turbo Sonic


« on: May 15, 2015, 01:10:49 PM »

My 2012 Chevy Sonic 1.4 turbo seems to be giving me hesitation / misfires (mostly noticeable when accelerating when the turbo is being used more heavily).  Had Oreilly do a code check and it is a P0449 and online that seems to be a pretty ambiguous code... supposedly EVAP vent valve control circuit open.  I had it do this within the past few months and ran some lucas and techron injector cleaner through it and it was fine for awhile.   

Car is under used / certified warranty, but not their $150 general diagnostic.. heh..  Seeing if there is any way I can get it figured out without taking it to them.  (Dave Gill)  Seems that my Aveo had the same or similar code, but it was a hard start issue.. once it ran it was fine. 
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Bub
Crashtest Dummy
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Posts: 1405

#13 STC Chevy Turbo Sonic


« Reply #1 on: May 18, 2015, 01:30:26 PM »

Seems that a few of you have read this, but had no input.  FWIW I've put about 280 miles through it after adding a bottle of Lucas injector cleaner and just within the last 50 miles or so I noticed all of the hesitation went away... how in the world does that engine check code equal what fixed it.  The check engine light is still on, but like my Aveo once I put on the air intake it was pretty much on solid for my entire ownership... nothing new there. 
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torquejunkie
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Posts: 2


« Reply #2 on: August 09, 2015, 09:35:52 AM »

If your CEL is still on give this a quick look..

http://www.gmtruckclub.com/forum/threads/how-to-fix-code-p0449-evap-pics-video-and-part-s.110446/

I don't see how the evap solenoid could be related to a misfire. I have seen it cause no start conditions immediately after refueling.. but I doubt that applies here.

You should have logged a misfire code.. and the way things are monitored these days I'd be surprised if a flakey injector wouldn't get flagged and logged...

Any chance you have a weak / loose coil pack?
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90 Jetta Coupe - 31 STF
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