forcing turn on of manifold heater with warm weather?

[ABailey]

Good day all:



Is it possible to force the manifold heaters to turn on when the outside temps are above the preset computer cut-off limit? Specifically I want to perform this as my truck belches a blue death clowd :{ for a good minute when temps are higher and the computer does not turn the heaters on. This is a serious nuisance where I live . Ofcourse death clowd is not produced with the heaters on. Thanks in advance for any feedback.

 

[Evan A. Beck]

Just wire in a momentary-on switch to activate the relays. Press it for 5-10 seconds before you start, and some of the smoke will go away. However, you will still have some smoke because under normal conditions, the ECM turns the heaters on after the engine is running. You may have to press the button a few times while it is idling to get rid of the smoke.

 

[fest3er]

Originally posted by Evan A. Beck

Just wire in a momentary-on switch to activate the relays. Press it for 5-10 seconds before you start, and some of the smoke will go away. However, you will still have some smoke because under normal conditions, the ECM turns the heaters on after the engine is running. You may have to press the button a few times while it is idling to get rid of the smoke.

More specifially, the PCM completes the circuit to ground; it can also run the heaters separately. Thus you need to run two wires (one from each relay secondary) to a two-pole momentary-contact switch in the cab, and from the switch to a good ground.



You might also want to ensure your fuel heater is functioning properly. Though cold fuel will generate white smoke when it is cold out, I think it could cause blue smoke when warm.



Also, what's the likelihood that oil is draining into the cylinders via the valve stems? Blue smoke on startup in gassers has always been a sign of this particular problem. BUt I don't know if it applies to our fantastic Cummins diesels.



Fest3er

 

[dresslered]

I would definitely be more curious as to why your truck is belching this smoke. Can you give us the particulars of your truck and the way it is set up? Does it have HUGE injectors, fueling box, etc. ? What year is it? Mine has never smoked regardless of the heaters coming on or not.

 

[ABailey]

more info on the problem

I only get this smoke when the manifold is cold (ambient temp). Once everything is heated, I don't get any visible smoke when I start. When it was cold outside, I would get some but not the same quantity I see now and I attribute that to the manifold heaters cycling when it is cold. When I started this morning the ambient temp was ~ 65F and I must have shortened someone's life if they got a lung full of that cloud . See below for info on truck; everything is stock for now . Thanks for the suggestions and help.

 

[illflem]

Couldn't you just trick the intake temp sensor into thinking it's cold with a switch and the appropriate resistor? This way you avoid having to switch high amps with a relay. A friend of mine does this with his 12 valve to keep the heaters from coming on when the temps don't require the preheating. Opposite of what you want but the same idea.

 

[dresslered]

illflem-

I believe that they are referring to just tripping the existing relays. The resistor trick might not be as clean as one might guess. The IAT sensor (as well as the MAP) are used for this measurement and by altering the resistance, you would also change the fuel/air mixture. The 12V's operate a little differently having a mechanical pump.



Supposeably, when the ECM reads intake manifold air temperature of 66-degrees or lower, the air heater pre-heat cycle is started. This is how it's suppose to work, anyway. I have heater grid LED indicators on my dash, and I have noticed quite a variation in the trip points even after the truck has sat for over 24hrs. (some times at temperatures in the 70's while other times at tempratures in the 50's???). I have always started my truck inside a carport and have never noticed excessive blue smoke regardless of the heater grids being tripped or not, however.



Aside from my original suspicion of overfueling (which it clearly is not based on ABailey's signature), I can only suggest to do what the others have recommended. Perhaps your IAT sensor is off in resistance values?

 

[Vaughn MacKenzie]

Blue Smoke = dirty injectors?

Back to the smoke topic I have noticed over the last few months my truck smokes much more at startup than it ever has before. Even now with the warmer weather it puts out a good blue haze and rich, strong exhaust odor for a minute or two. Even when my DD2 injectors were installed it would never smoke at startup until it got pretty cold. Now it smokes like a cold day when it is reasonably warm out.



I have seen comments about the fuel being pretty bad and guys who have recently pulled injectors say they are carboned up bad. This will definitely reduce fuel atomization and produce more smoke. I have used a fuel conditioner on most tanks but if the fuel is not that good then deposits may still form on the injector tips.



During the week I rarely get on the road and my trips are short and taken at low speeds. It seems when I take it out on a trip and drive it hard it burns cleaner at the next cold startup.



ABailey, I found that after I wait a few seconds for the oil to circulate I cycle my engine speed between 1300-1900rpm several times and the smoke clears much faster than if I just let it idle. Also take off within 45-60 seconds after startup and that will clear it up faster due to the increased load on the engine (but don't go rompin' on it 'til the temp comes up).



Vaughn