Thats what I was thinking, The cam position senser has to pick up the "dead spot" or the spot with the missing tooth to even begin so it know where to start. That can take up two 2 revolutions alone depending on where the cam stops when it was last shut off. The smoke is reduced through proper heating of the glowplugs and/or air heater grid. I think the newer trucks (ford anyway) include both. I think even some of the later 7.3 powerstrokes had a grid heater in the Y pipe connection to the intake along with the original glow plugs. Also, to decrease smoke on startup, the computer changes injection timing and number of injections per cylinder per stroke. I think they can do 2-3 injections per stroke with the piezo electric injectors in the new international engines. I also belive that the ecm waits until the minumum preset cranking rpm is reached before it starts it injection cycle. Then we have the regnereration systems on these new 08 trucks (I'm only familer with the ISX one but I guess the others are close to the same) that helps reduse suit out the pipe. In that system, when the particulate filter gets full of suit, The computer tells an diesel injector that is placed right behind the out exhaust on the turbo to inject fuel to increase the exhaust temp to 12000-14000 degrees to burn off the suit. You also mention long crank times, Has anyone ever started a vt275 international engine. Its a V6 twin turbo diesel. Takes forever. Its like starting an IDI without glow plugs on a cool day.

Man, these things get complicated. I sure like the simplicity every now and then on these older engines. Got fuel, got compression, glow plugs (or either) and boom, were running. These new ones hurt my brain!!!

 

My thinking about smoke is that our engines start to sqiurt fuel into the chamber as soon as the engine starts turning leading to an imperfect injection in some of the cylinders, instead of after the engine has been spun several times and getting a perfect spray everytime. Not sure if thats actually whats happening. My truck makes the same size of smoke puff every time no matter if its hot or cold.

 

OK...good discussion...I am learning even more.

Another question.

Mine starts now pretty well, bu it is 70 in the AM. Here is the NW section of Arkansas it gets cole in the winter but not terribly cold...maybe in the 20/30s sometimes.

Do I in the winter change my startup procedures...such as...

Turn on ignition, wait 10 seconds for glow plugs to heat up and then start? Does the glowplug light on 6.9 1984 model go off after so many seconds indicating the glow plugs are toasty?

Does pressing the accelerator pedal a couple of times get any fuel flowing prior to cranking the starter? Not like there is a bowl of fuel sitting around waiting to prime the intake.

Tim

Tim

 

Are you running manual glow plugs? 10 seconds is fine as long as you are using the Beru/Motorcraft (germany) brand. Other brands are unreliable and heat up much faster.

Pumping the pedal does nothing unless the engine is on and turning over already.

 

They seem to be automatic. I do nothing.,...turn the ignition on and the glow plug light comes on. When it is running...the light is off.

It made no sense that the pedal did anything like a carb gas engine.

 

Throttle pumping on a diesel (or even fuel injected gas motors) does exercise your right leg calf muscles, but that is all it does.

The throttle is hooked to a spring in the IP govenor on diesels.

 

I believe it's best to hold the accelerator midway while cranking, so the cold start/high idle solenoid can extend and hold the idle high till the engine warms up. It doesn't have enough power to push the throttle open, but it does have enough to hold it there.

Also if you notice your glowplug light not staying on very long, it may be a sign some of the glowplugs are burnt out.

 

The old style system used from 83 thru 86 uses a timer to time the glow plug cycle.

The only way to tell if glow plugs are burnt out is check them.

The glow time is the same for 2 plugs or 8 plugs.

The old system uses Motorcraft/Beru ZD 1A glow plugs.

 

Yes, when I noticed the light not staying on very long because of bad glowplugs, it was on a 89. Glad you caught that, I didn't know the old ones didn't work that way.

 

I'm getting quicker starts since I upgraded my starter to one of the Mitsubishi (sp?) style gear reduction units. It spins much faster.
Mike