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How does operating temperature affect TBI?

Discussion in 'The Garage' started by sled_dog, Apr 6, 2005.

  1. sled_dog

    sled_dog 1 ton status

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    What is the proper engine operating temperature for a TBI motor? My 89 Burb has a 180* stat in it and runs around that pretty steadily. I never thought a thing about it until today when we talked cooling systems in class. I realized maybe this is a factor in my suspected rich condition. Does TBI run richer when running a cooler thermostat? Wondering if I should be switching to a 195 or + stat.
     
  2. RustyMule

    RustyMule Registered Member

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    Computer controlled engines are calibrated for a certian temp. Running it cooler than stock would make the computer think the engine was still cold and richen it up. Put it back to the stock thermo and see if it gets better.
     
  3. beastofablaze

    beastofablaze 1/2 ton status

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    when you first start your truck in the morning the computer tells it to run rich until it gets warmed up so general logic would suggest that cooler temps means richer and hotter temps means leaner... which makes sense when you consider pinging only occurs when a motor is either hot or has too high compression.

    180* is right where you should be...
     
  4. chevyjeff

    chevyjeff 1/2 ton status

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    My tbi 350 runs better hot 200 + or -, I would run the factory 195 thermostat to make the computer happy.
     
  5. BIG STEVE

    BIG STEVE Registered Member

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    The last guy has it right put the stock stat in all your doing is wasting fuel
    newer eng run better probley older ones also above 200
     
  6. ntsqd

    ntsqd 1/2 ton status

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    A friend of mine built a switch box for the ECT on his 454 TBI. He tested the resistance at various temps and the switch could select btwn the sensor and various fixed resistances for a little more power when pulling grades.
     
  7. sled_dog

    sled_dog 1 ton status

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    eh I won't agree about older engines, fuel injected I likely will. My carbed 355(same motor thats in my Burb with the TBI on it now) ran like a bat out of hell around 160-170. Now it runs like crap when cold and somethings just not right about the tune so first thing I'm gonna do is go back to stock stat.
     
  8. afroman006

    afroman006 1/2 ton status

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    Wow, the 350 in my burb actually runs better cooler. I put a 160 degree thermostat in there cause it gets over 100 during the summer here and that plus the electric fans keeps it at about 160 cruising or in traffic. It starts pinging when it gets above 200, I dont know what the hell is wrong with it, its a Mr. Goodwrench reman with I assume stock compression. I've heard my timing could be off but it only pings when the temp gets high. I think it might be the Bosch double platinum plugs I have but I'm not sure. I'm gonna swap them out with AC Delcos one way or the other.
     
  9. BIG STEVE

    BIG STEVE Registered Member

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    Heat can effect carbaraters fuel delivery although i know its like gold
    but with pinging ide try some higher octane fuel the higher temp will
    boost coppresion
    WE have dyno emission tests here ive gotton some older stuff passed
    with a hotter stat just seems to burn more complete.

    90 jimmy x city vehicle 350 sm 465 no a/c no power gm am fm no carpet or headliner how can something that hot in the summer be so cold in the winter
    :D
     
  10. RustyMule

    RustyMule Registered Member

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    My old beastly beast runs better at 180*. 195 seems too hot for the old engine at 230K
     
  11. smokkey1

    smokkey1 1/2 ton status

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    same here my 350 tbi sub doesn't like to run very hot either.
     
  12. sled_dog

    sled_dog 1 ton status

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    eh well my motor has maybe 10,000 miles on it, MAYBE. A little under 9:1 compression. Its never pinged in its life :D
     
  13. randy88k5

    randy88k5 1/2 ton status

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    IMHO, when I worked at the counter, Ive never seen such a waste of money. Bosch did a good job advertising them, but Ive never heard anyting but dissappointment out of them. The center electrade is so small, it doesnt clean very well. Any amount of oil will foul them out.

    Ive heard they work pretty decent in some european cars (go figure), but nothing but problems in American and Japaneese cars. I nearly stopped selling them, because I was tired of customers coming back tellimg me I sold them crap.

    I would get rid of those plugs and get a quality set of Delcos before you do anything else.

    End of rant.
     
  14. afroman006

    afroman006 1/2 ton status

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    I'm going to swap them out today. I was talking to a guy in my club who drives a jeep grand cherokee and he has the same pinging problem I do and the only thing our vehicles have in common is the bosch plugs. Out they come.
     

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