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Discussion Starter #1
recently was on a trip through Wy and my grid heater kept cycling on and off. I would get a loud backfire sound and large puff of black smoke. Dealership said nothing wrong, any damage and what could have caused this
 

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No idea what caused it...at those speeds you should be able to sustain coolant temperatures. Aside from that, I think it's supposed to shut off after you start moving...
 

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theres definetley something not right there and the dealership says nothing is wrong????? that could cause some seroius engine damage
 

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My grid heater shuts off at around 18-20 MPH. It is not normal if the grid heater comes on at any speed over 20 MPH. Don't understand why the Dealership said it was OK for it to do so! BTW, I've driven my truck at -24 Below zero and not had the grid heater come on while driving at any speed above 20 MPH.
 

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Are you sure it's the grid heater? If so then something is messed up because it shouldn't come on after 20mph. The only thing's I know of that control the grid heater is the IAT, Coolant Temp sensor, and ECM.
 

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Bad valve? The dealer should be able to do a power balance test to see.

:popcorn:
 

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If nothin else you could check the vlaves like Shockwave said, pop the valve cover off and take a look at the everything
 

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Might fill out your signature and let us know what kind of truck and mods you have.

The grid heaters shutoff above a set RPM and speed. At that point, the speed at which the air is compressed, regardless of the air temperature, will make it hot enough to combust at injection.

What made you think the grid heater was cycling at 75 MPH? Can you explain more about the "backfire" sound? In theory, it is impossible for a diesel to backfire in the traditional sense. Understanding the symptoms might help aid in a better diagnosis.
 

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A backfire/ bursting, will occur if the rail is run out of fuel. But this case seems strange.



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the grid heater will not cause a backfire or black smoke you need to add a fuel pressure gage to check when to change fuel filter i do not know if you starve the cp3 if it will cause it but i agree it is either a stuck injector or a rail pressure problem if the grid heater did cycle during this time that points to the ecm not good
 

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Discussion Starter #11
thought it was grid heater volt meter would bottom out light dim fan slow the puff of smoke and audible bang sorta like backfire this was some time ago about 27k so made it home asked dealership about it they played dumb looked at it changed fuel filter have not had a problem since oil level has always seemed high. a diff delership told me they had no way to do an oil analysis.
 

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If you want to do and oil analysis (aka UOA) you can use Blackstone or Amsoil.
 
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