Huge difference between digital probe and onboard thermometer temperatures - Need Help

Discussion in 'General Discussion' started by whitedogbbq, Sep 9, 2015.

  1. whitedogbbq

    whitedogbbq Newbie

    This is actually my first post but I wanted to say that this forum is awesome and it's already been so useful during my first few cooks.  I really appreciate all of the information and helpful support found in the community thus far!

    Anyway, I'm having issues with my thermometers.  I'm cooking on a Masterbuilt XL 40 gas smoker and I'm using an Ivation dual probe digital thermometer.  I did a boil test and found that the digital thermometer is about 2* off and my onboard analog thermometer is 10* off.  I'm using the including probe clip and clipping on a grill near the middle of the smoker, directly underneath the rack that I'm using to cook on.  It's probably about 4" from the meat.

    Here is the problem.  I've cooked spare ribs a few times and have used a cook temperature of 275 according to the digital, but the door thermometer reads anywhere from 315-325*.  This hasn't been too much of a problem with ribs because I just pull them when they pass the bend test which has been anywhere from 3.5 to 4.5 hours without foiling.  When I did a 10 pound brisket, I held at 250* according to the digital, but got to the stall at 165 in roughly 4 hours which seems way too fast.  The brisket subsequently came out a bit less moist and tender than I wanted because I suspect it cooked way too fast.  I got to 200* in about 7 hours.

    Any idea why my probe and door thermometer are ranging anywhere from 30-60* apart despite the fact that they were only 10* apart in the boil test?  I've cleaned and re-tested both thermometers and there doesn't seem to be any issues with them.

    Thanks in advance!
  2. golfpro2301

    golfpro2301 Smoking Fanatic

    Dont worry too much about it. Probably due to two reasons. 1- how heat circulates in your smoker. 2- your digital probe is on center of rack and door thermometer stem isnt anywhere close to center. I have same issue on my pitmaker vault. I bought a large Tel Tru that is spot on with boil test. I put my guru probe in center of rack and my tel tru in door will be off by 10 degrees. The stem is short of the center of the racks by 6-8 inches I would imagine. Try putting probe on stem of door thermo and look at difference. You will probably see same difference as boil test
    whitedogbbq likes this.
  3. chef jimmyj

    chef jimmyj Smoking Guru Staff Member Moderator Group Lead OTBS Member

    I totally agree with the Pro...JJ
  4. wade

    wade Master of the Pit OTBS Member SMF Premier Member

    Yes, I agree too
  5. dirtsailor2003

    dirtsailor2003 Smoking Guru OTBS Member

    Agreed with all above. I don't use the built in therm in any of my smokers, and all the smokers I have built never get a built in therm. All of the probes for my iGrill2 are with 1* for the altitude that I am at. Honestly for pit temp measurement I'd be happy with 5* off. For meat especially beef I want it to be as close to spot on as possible.
  6. whitedogbbq

    whitedogbbq Newbie

    Thanks for the replies.  So do you guys think I should just trust the reading I'm getting off the digital prob in the middle of the box and ignore the door thermometer?  That's what I've been doing thus far...
  7. dirtsailor2003

    dirtsailor2003 Smoking Guru OTBS Member

  8. jckdanls 07

    jckdanls 07 Master of the Pit Group Lead OTBS Member

    Yes.. as said above... trust your digital therm before you put any faith in the door therm... also... You said you put the probe for your digital UNDERNEATH the meat... This is not a good placement for the probe as the juices drip from the meat onto the probe and it will make your readings go wacky... put the probe on the same grate as the meat right beside the meat...
    whitedogbbq likes this.
  9. whitedogbbq

    whitedogbbq Newbie

    Great advice, makes perfect sense.  I'll move it next time.
  10. golfpro2301

    golfpro2301 Smoking Fanatic

    What Jckdnaiels said. Always put probe close to meat on same rack. Along with probe going wacky moisture could short it out if it gets down in the sleeve. As far as which thermo to trust Always trust your digital that ia going to be way more accurate than door

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