Bucking and Surging During Idle - Chevy Cobalt Forum / Cobalt Reviews / Cobalt SS / Cobalt Parts
Problems and Service Talk about any mechanical problems you are having

 
LinkBack Thread Tools Display Modes
post #1 of 10 (permalink) Old 08-04-2019, 02:29 PM Thread Starter
Newcomer
 
Join Date: Jun 2016
Posts: 7
Garage
Bucking and Surging During Idle

I honestly don't know what's going on and it's getting slightly irritating now. For the past two years since December 2017, my car likes to buck like it wants to take off by itself when sitting at a light and idling. The list of things I have done to try and fix this problem is:

Replace MAF sensor
Clean the throttle body
Replaced the throttle body with a used one
Replaced spark plugs
Replaced coil pack
Replaced Brake booster and hose
Replaced intake snorkel that attaches to throttle body to air box (4 times)
Replaced intake manifold gasket(twice)
Replaced valve cover gasket
Replaced TCM (that actually failed though lol)
Replaced PCM and ECM combo
Replaced Fuel Pump (twice, never ever buy GMB brand fuel pumps ever again. Sticking with OEM)
Replaced Fuel filter
Replaced Fuel injectors
Replaced Purge Valve solenoid
Replaced MAP sensor with a used one
Also replaced both O2 sensors and catalytic converter with ZZP downpipe and cat combo.

I'm honestly lost with what in the world is going on with my car and I refuse to give up because I love it so much. After I replaced the Fuel pump my hesitation under acceleration had stopped and I'm finally getting the correct mpg my car is supposed to have and long term fuel trim is between -3 to -12. Anything would help. Thank you for taking the time out to read my post!
ZRJO is offline  
Sponsored Links
Advertisement
 
post #2 of 10 (permalink) Old 08-04-2019, 04:52 PM
Prospect
 
user00265's Avatar
 
Join Date: Sep 2018
Location: Winona, MN
Posts: 15
Is it throwing any codes? CEL on at all?

I can't think of much more to check other than transmission, PCV system entirely... He'll, even low refrigerant on the A/C as that can cause the clutch on the compressor to engage/disengage causing a similar effect.
user00265 is offline  
post #3 of 10 (permalink) Old 08-06-2019, 07:27 AM Thread Starter
Newcomer
 
Join Date: Jun 2016
Posts: 7
Garage
Surprisingly no DTCs. It used to throw p0442 and p0172 but I replaced the fuel pump which was causing my car to throw p0172, but, P0442 just went away by itself. What would cause the transmission to make these symptoms occur? What park of the PCV system would cause a vacuum leak to do this? Lol I wouldn't be surprised if my A/C was causing it, but it blows pretty cold, especially when the car has been running for like 5 mins. Also thanks for the quick reply!
ZRJO is offline  
 
post #4 of 10 (permalink) Old 08-06-2019, 02:01 PM
Prospect
 
user00265's Avatar
 
Join Date: Sep 2018
Location: Winona, MN
Posts: 15
Clutch slip. Converter slip. Surging when it re-engages. Transmissions are very... Interesting on how they behave when they're having issues. Varied. Might not even be that, but I've experienced surging with a bad transmission.

As for the PCV/Vacuum, well, anything. Loose hose, loose fitting, cracked assemblies... Only real way to know is to put a gauge somewhere in the vacuum system and see what it does.
user00265 is offline  
post #5 of 10 (permalink) Old 08-06-2019, 02:15 PM Thread Starter
Newcomer
 
Join Date: Jun 2016
Posts: 7
Garage
Would a transmission low on fluid also cause it? And I checked my crankcase hose and it might be the culprit but, I'm going to buy a new one and see if that fixes it. Because I've replaced basically everything but the transmission and the engine itself. lol
ZRJO is offline  
post #6 of 10 (permalink) Old 08-06-2019, 03:52 PM
Prospect
 
user00265's Avatar
 
Join Date: Sep 2018
Location: Winona, MN
Posts: 15
I'm not the authority, I only speak from experience... But it could be. There's so many other little things that it can theoretically be that... Well... Yeah.
user00265 is offline  
post #7 of 10 (permalink) Old 08-08-2019, 11:53 AM
Newcomer
 
Join Date: Jul 2019
Posts: 2
Don't overlook the throttle position sensor. Just a thought. Good luck!
Rcfitch is offline  
post #8 of 10 (permalink) Old 08-13-2019, 08:19 AM Thread Starter
Newcomer
 
Join Date: Jun 2016
Posts: 7
Garage
Thank you everyone for your replies! Quick question though but, can a massive exhaust leak cause this problem?
ZRJO is offline  
post #9 of 10 (permalink) Old 08-13-2019, 08:53 AM
Prospect
 
user00265's Avatar
 
Join Date: Sep 2018
Location: Winona, MN
Posts: 15
Quote:
Originally Posted by ZRJO View Post
Thank you everyone for your replies! Quick question though but, can a massive exhaust leak cause this problem?
Yes... Sensors on the exhaust can be giving the car feedback about air in the exhaust making it do so.
user00265 is offline  
post #10 of 10 (permalink) Old 08-13-2019, 08:55 AM Thread Starter
Newcomer
 
Join Date: Jun 2016
Posts: 7
Garage
Okay that makes a lot of sense because yesterday on my way back home, my exhaust manifold made a huge exhaust leak and made my car sounded like a pissed off lawnmower lol
ZRJO is offline  
Sponsored Links
Advertisement
 
Reply

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome