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  1. #1
    Join Date
    Aug 2011
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    s.california
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    Default **cold start up help**

    hello again all,
    have a little problem and need a help. when i start the jeep in the morning or after being parked for a awhile in cold weather if i give it any gas it stumbles or sounds like its choking/bogging down. thats only if i apply gas peddle.. if i start it and just put it in drive and go or dont touch the gas you wont even notice the problem. if it sits in the sun and i start it, it doesnt do it. ONLY COLD starts not hot.. now when i give it gas and it chokes/bogs and i let off the gas it imediatly stops bogging/choking and idles great! give it gas and it bogs/stumbles again. let off and its fine again. this only lasts for maybe 20 seconds. after that it will not do it again til next morning start and all day its fine, idles fine, accelerates fine. due to a different problem this is a list of whats newly replaced recently...
    *plugs (champion .35 gap)
    *wires
    *cap and rotor
    *map sensor
    *ECT sensor
    *IAC valve (cleaned throttle body and iac passage)
    *fuel injector cleaning (through rail)
    *IAT sensor
    *fuel filter
    *air filter
    *all vacuum hoses
    *battery
    *o2 sensor (denso brand, accidently dropped before install=problem?)
    *oil and filter change
    *fuel pressure regulator
    after reading a bit im thinking possibly when i dropped the o2 sensor the heater element inside broke. i read its to help get the o2 online faster in the mornings to get a/f ratio regulated. shifts fine cold or hot and has NO other signs of any problems after warmed up 20 sec.
    any ideas what might cause this ONLY on cold start for maximum of 20 seconds??

  2. #2
    Join Date
    Sep 2009
    Location
    Chico, CA
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    Default Re: **cold start up help**

    Not sure on this. If the O2 heater malfunctions, you should get a check engine light
    230 hp 4.3L Chevy
    Built 4L60E with manual lockout
    Atlas 4 speed
    Griffin radiator
    On board air
    Warn 9.5ti on custom bumper
    7.5" RE front and bastard pack rear on custom long arms
    30 gal gas tank
    lockers
    And a bunch of other stuff

  3. #3
    Join Date
    Aug 2011
    Location
    s.california
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    Default Re: **cold start up help**

    i read about o2 heaters bad turning on cel light and also that OBD1 is not as sensitive to setting a cel light in my case.. but that OBD2 is sensitive to this kinda fault. only thing i know for sure is its a COLD starting issue only....

  4. #4
    Join Date
    Sep 2009
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    Chico, CA
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    Default Re: **cold start up help**

    Unless you get a total failure, there is no way for the PCM to measure the O2 for function. All it sees as data. The heaters fail, as in open circuit, then it triggers a light. Since you didn't have this problem before the injector install, I suggest you look there and the coolant temp sensor. If it is not working, the PCM will run it rich like a fresh start up
    230 hp 4.3L Chevy
    Built 4L60E with manual lockout
    Atlas 4 speed
    Griffin radiator
    On board air
    Warn 9.5ti on custom bumper
    7.5" RE front and bastard pack rear on custom long arms
    30 gal gas tank
    lockers
    And a bunch of other stuff

  5. #5
    Join Date
    Aug 2011
    Location
    s.california
    Posts
    179
    Chats
    2

    Default Re: **cold start up help**

    actually i didnt install new injectors i just had them cleaned through a fuel injector cleaning service through the fuel rail. the problem was there before all the parts were changed. ECT is also new. i have no check engine light on, no stored codes. runs great the rest of the day.bunch of new parts... im not sure where else to look??

  6. #6
    Join Date
    Sep 2009
    Location
    Chico, CA
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    Default Re: **cold start up help**

    I would still look at the coolant temp sensor, the one by the tstat housing
    230 hp 4.3L Chevy
    Built 4L60E with manual lockout
    Atlas 4 speed
    Griffin radiator
    On board air
    Warn 9.5ti on custom bumper
    7.5" RE front and bastard pack rear on custom long arms
    30 gal gas tank
    lockers
    And a bunch of other stuff

  7. #7
    Join Date
    Aug 2011
    Location
    s.california
    Posts
    179
    Chats
    2

    Default Re: **cold start up help**

    i will test it today to make sure its not a defect part. is there anything else i should test or take a look at? any part i think of as a culprit im reminded that it works through out the drive just not cold and thats what puzzles me...

  8. #8
    Join Date
    Sep 2009
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    Chico, CA
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    Default Re: **cold start up help**

    That is why you should look at that CTS. It affects mixture with engine temp
    230 hp 4.3L Chevy
    Built 4L60E with manual lockout
    Atlas 4 speed
    Griffin radiator
    On board air
    Warn 9.5ti on custom bumper
    7.5" RE front and bastard pack rear on custom long arms
    30 gal gas tank
    lockers
    And a bunch of other stuff

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