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Misfire and rough idle

Tiny
ANDREA KING
  • MEMBER
  • 2011 CHEVROLET TRAVERSE
  • 3.6L
  • V6
  • 2WD
  • AUTOMATIC
  • 160,000 MILES
Two weeks after routine oil change, drove car an hour then left running in idle for about 10 minutes. It started idling really low and rough around 500 rpm's and check engine light came on. Ran codes and they are random misfire, misfires in 2 4 and 6 cylinders. P2187 and p2190. We changed spark plugs, checked for any noticeable leaks in vacuum lines. Used fuel injector cleaner. Cleaned throttle body and MAF sensor, changed an O2 sensor that was showing pinned at.96. Fuel pump shows 45 psi. We've cleared the codes after these and the same ones return. In cold start it starts right up and idles about 1300, sounds great and then it drops to 500 and starts misfiring. After warmed up and turned off it doesn't want to start back up, but will if you press the gas while cranking. Hasn't stalled at all. Once its started it will run. Barely, but runs. The rpm needle seems to bounce all the time and when you press gas pedal rpm's go down before going up you have to give it more gas than normal to speed up. Please help!
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Sunday, December 8th, 2019 AT 11:38 PM

4 Replies

Tiny
SCGRANTURISMO
  • MECHANIC
  • 4,897 POSTS
Hello,

Okay so I would inspect your vehicle's Mass Air Flow sensor [MAF], and the air filter along with the air intake tract to make sure that there is no unmetered air leaking in. Check that there are no bugs or foreign debris in the MAF sensor. You can purchase special MAF cleaner manufactured by CRC at any auto parts store and clean your vehicle's MAF by spraying the small wires that run across inside the MAF. Be careful though, as they are delicate and cannot be broken. In the diagrams down below I have included the diagnostic troubleshooting guides for both Direct Trouble Codes[DTC][s] P 2187 and P2190 from the vehicle manufacturer. Please go through these guides, check the components, and get back to us with what you find out. We can go from there.

Thanks,
Alex
2CarPros
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Monday, December 9th, 2019 AT 3:02 AM
Tiny
ANDREA KING
  • MEMBER
  • 3 POSTS
Thank you. We cleaned the MAF again with no change. I've read a lot about the PCV on this vehicle getting gunked up messing with the vacuum. I watched a video that said you could remove the PCV hose while idling and feel for suction. So I did and there was no suction at all and was gunked up with oil, also the other end of hose where it attached to the nipple on the air mass meter boot, the nipple broke off of it when I tried to remove hose, I wasn't rough on it so I'm thinking that also was cracked. I'm going to have my mechanic remove the cam shaft cover and clean out the PCV, replace camshaft gasket and replace air mass meter boot. Just want your opinion and if you know anything about the PCV's in these vehicles getting plugged and if that sounds like my problem to you.
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Wednesday, December 11th, 2019 AT 1:19 PM
Tiny
ANDREA KING
  • MEMBER
  • 3 POSTS
Picture of where nipple broke off of air mass meter boot.
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Wednesday, December 11th, 2019 AT 1:46 PM
Tiny
SCGRANTURISMO
  • MECHANIC
  • 4,897 POSTS
Hello again,

That would definitely do it. The Positive Crankcase Ventilation [PCV] is a system where the crankcase gases get circulated into the engine and burnt with the normal combustion of the engine to keep the pressure in the crankcase down and the environment in it as clean as possible. The PCV valve has a ball in it that is used as a check valve and gets sucked up and down with the vacuum from the engine. They are prone to getting plugged up with oil from the air in the crankcase. If there is a leak anywhere in the intake/vacuum/EVAP systems on your vehicle, it will allow unmetered air, or air not accounted for by the PowerPoint Control Module [PCM] or "computer", that will cause unstable idle, driveability concerns, and if it gets to bad can cause catastrophic engine failure in the way of your engine going lean and self destructing. Please get back to us with how everything turns out, and I hope this helps.

Thanks,
Alex
2CarPros
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Wednesday, December 11th, 2019 AT 6:58 PM

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