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2003 Volkswagen Passat Rough Idle

Tiny
DAVEK24
  • MEMBER
  • 2003 VOLKSWAGEN PASSAT
  • 126,000 MILES
2003 passat 1.8t awm 126,000mi b5.5 Rough Idle a few minutes after starting. Codes p0300.0301, 0302,0303. Cleared them still reappearing. VW replaced coils, I replaced spark plugs. Still same results. Checked for vacuum leaks. Found cracked pcv oil breather hose. Did not install yet. Could this be the problem. Have not checked the pcv valve under the manifold yet. All other hoses seem ok. Am also getting suction when I remove the oil filler cap when running, could that be the pcv valve and the cracked hose or am I missing something. Dave
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Saturday, August 24th, 2013 AT 9:15 PM

9 Replies

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Pcv hose would cause this.

Did you do a compression test? I would start there.

The vacuum in the oil cap could indicate a vacuum leak from the intake manifols.

Roy
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Sunday, August 25th, 2013 AT 6:13 AM
Tiny
EXOVCDS
  • MECHANIC
  • 1,883 POSTS
Had the same issue on a passat last week... here's a video of the faulty PCV Check Valve:

http://www.youtube.com/watch?v=UH5LD7HP0YM

Feel free to do a compression test first... if you want.

Thomas
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Sunday, August 25th, 2013 AT 11:32 AM
Tiny
DAVEK24
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  • 23 POSTS
Roy, did a compression test and is in specs. Reset the codes today. Put new gas. Premium about eighth of tank and poured in about a pint of acetone. Ran the car hard. Ran great on the road with no cel. Came home and let idle. Idle better, then cel started blinking again and got two extra codes besides the p0300, 0301. Etc.P1176 and p0299. But still have not replaced the pcv oil breather hose or the pcv valve under the intake. Will come in mail this week and will replace but cleared the codes again and ran great while driving then on idle. Rough. Got the p0300's again. But not the other codes. Hopefully the pcv and the oil breather vacuum hoses are to blame. Dave
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Sunday, August 25th, 2013 AT 3:35 PM
Tiny
DAVEK24
  • MEMBER
  • 23 POSTS
Thomas, did a compression test and is in specs. Reset the codes today. Put new gas. Premium about eighth of tank and poured in about a pint of acetone. Ran the car hard. Ran great on the road with no cel. Came home and let idle. Idle better, then cel started blinking again and got two extra codes besides the p0300, 0301. Etc.P1176 and p0299. But still have not replaced the pcv oil breather hose or the pcv valve under the intake. Will come in mail this week and will replace but cleared the codes again and ran great while driving then on idle. Rough. Got the p0300's again. But not the other codes. Hopefully the pcv and the oil breather vacuum hoses are to blame. Dave
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Sunday, August 25th, 2013 AT 3:45 PM
Tiny
EXOVCDS
  • MECHANIC
  • 1,883 POSTS
Disconnect the pcv hose at the manifold and plug the manifold end with your finger (like in the video). Let me know what happens at idle.

Thomas
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Sunday, August 25th, 2013 AT 4:22 PM
Tiny
EXOVCDS
  • MECHANIC
  • 1,883 POSTS
Any luck yet?
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Friday, August 30th, 2013 AT 4:38 PM
Tiny
DAVEK24
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  • 23 POSTS
Thomas, Have not gotten a chance to look at it again, but will tomorrow. Just got all the parts in the mail to replace, it's my daughters car and she needed it for school. Will replace the cracked oil breather hose along with the new pcv valve and surrounding hoses. Will post my results in a few days. Thanks again. Dave
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Saturday, August 31st, 2013 AT 3:48 PM
Tiny
EXOVCDS
  • MECHANIC
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Thanks. Sorry about nagging you for updates!

Just want to be sure you get it solved.

Thomas
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Sunday, September 1st, 2013 AT 10:59 AM
Tiny
DAVEK24
  • MEMBER
  • 23 POSTS
Success. Runs better than good.I knew the oil breather hose was cracked but the pcv valve just fell apart. Replaced both. Cleaned out hoses and replaced one check valve, cleaned out the others and new hose clamps. Idles smooth and no more CEL. Thank you everyone for their input. Dave
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Tuesday, September 17th, 2013 AT 9:48 AM

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