Stumble, unstable idle, no related codes

Tiny
JEEP2002
  • MEMBER
  • 2002 JEEP GRAND CHEROKEE
  • 4.7L
  • V8
  • AWD
  • AUTOMATIC
  • 180,000 MILES
I have code for B2S2 voltage to high I don't think it is related as you know this sensor only monitor's cat efficiantcy however it acts like it is a vacuum leak stumble at idle and revs up intermittently to 1000 rpm I have a scan tool and have watched the fuel trims there is little change in short or long term fuel trim when this happens +/- 5 % the long term dose creep up over time to +14 % during idle Map is reading 30 or so Kpa that is about 8.8 in hg I think but comes down when accelerating or cruising (Like a vacuum leak) but I can not find a vacuum leak also it blows smoke it dose not do it predictably like ring or valve guides would but just at random I have replaced the PCV. And clues as to were to look next
Tuesday, April 21st, 2015 AT 2:49 PM

1 Reply

Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
See pic for diagnosis we only get a p1492 code for that no b2s2 code listed. Also try cleaning throttle plate on both side and iac hole with choke cleaner and look for air leaks as well like between maf and throttle plate, any grommet not sealing on engine.
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Wednesday, April 22nd, 2015 AT 8:11 AM

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