- Why Does My Car Run Better With O2 Sensor UnPlugged?
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    1. 02-18-2008 01:51 PM #1
      I just bought and wired up a New Sensor and it is starting to give my tiny backfires. It runs like a top without the O2 Sensor. What is wrong??/

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    3. Member V-TEC this!!!'s Avatar
      Join Date
      May 4th, 2003
      London, Ont/Krakow, PL
      2002 Jetta TDi, 1990 G60 Corrado
      02-18-2008 03:22 PM #2
      Check the wiring that goes to the o2....I had the same problem....wires were very corroded!!!!
      Ran a new plug on both ends and it runs good!!!

    4. 02-19-2008 08:51 PM #3
      if fouled the sensor will make the car run rich. replace it with a new one. its part of normal maintenance.

    5. 02-20-2008 12:21 PM #4
      Check all the ground wires in the engine bay. That was my problem after having the same issue.

    6. Member Snowhere's Avatar
      Join Date
      Jul 26th, 2007
      BV Colorado
      one Chevy, one Audi, one VW, one Beemer, dead but not forgotten, and one Suzuki
      02-20-2008 12:22 PM #5
      I was reading your other thread on this and it could be you have a problem elsewhere in your wiring. Have you verified that the proper wires are getting power at the plug?

    7. 02-20-2008 11:48 PM #6
      bad wiring; blown ecu op-amps; bad grounds
      variable crankshaft timing or bad timing.
      you can use the boost gauge or mfa to test idle hg.
      warm: 195F operating temps (no less!)
      840rpm idle @ 260/268 cam 12hg
      840rpm idle @ 260 cam about 13-14hg
      840rpm idle @ stock cam 15hg
      or use a timing gun.
      example of bad timing is 5-9hg at idle; will fart alot and lower idle and loss of power.
      too much timing will ping (broken pistons!), and the idle will surge up/down up/down;

      I just feel it out on a warm day using my ears and the idle hg and set it up for 6-7BTDC.
      variable crankshaft keyway would be really bad; i'd inspect for that.

    8. 02-28-2008 07:40 AM #7
      my idle goes up & down Up & down sometimes right after I start it but it has been less pronouned lately.
      Which setting is the idle Hg? and are you saying to get the car to warm temps then check? My temp gauge stays right in the middle, is that 195F?

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