Actually yes they can. When I used to tractor pull, there was a fine line to make power. If you could back the fuel off and inject more water with the water injection it would make great power.
Too much fuel kinda puts out the fire. Either way, there was a big mushroom cloud of smoke but the exhaust might be more gray than black. Obviously this is different, but maybe a pyrometer might be a good idea to look at.
Too much fuel is running to rich - which is very possible in a diesel. Too much fuel either means that there isn't enough oxygen to burn or that the engine can't take the heat which is where water injection mainly helps.
A diesel always burns lean, the air being sucked into the engine doesn't change based on load for naturally aspirated, turbos change things somewhat but the basic concept is similar. Too lean means the engine wouldn't keep itself turning, but a lean ratio isn't going to hurt anything. If you step down on the throttle of a diesel engine at no load, vs while engine in under full load, there is a significant difference in the amount of air going into an engine.
If you run too big a turbo for your fuel system, you can burn down a motor without enough water. We never wanted to see a clear stack while mid run pulling. You can change pyro temps by changing rate, and timing of fuel injection.
Find somebody that pulls and look at data logs. Pulling guys know how to make power, no argument at all there. However, I did mention my comments were based on naturally aspirated and that turbos changed things somewhat. The basics are still similar when the general concept is understood along with understanding how a turbo works and why. I haven't looked at data from a puller, but I have looked at a lot of data from a large engine manufacturer during my day job.
As far as scoring the cylinder - you are correct. When somebody mentions lean or rich, I think of ratios and gasses, not lack of lube and cooling when running hot with less fuel than it should be getting. So I suppose it would be fair to say that a 'too lean' condition can be caused by prior mechanical failure like a plugged tip.
Water and excess fuel black smoke help keep the engine from melting down when it is overloaded from too rich a charge, not from a lack of fuel lean. But I still maintain that in the OP's general case - regular tractor, not being overloaded - there is no such thing as running too lean. Yeah, I'll agree with that. We do know that the lubricity nature of diesel fuel is one of the reasons why diesels have a long engine lifespan.
The ops chip though could be causing high egts. If he doesn't need the power, take it out. Nothing in life is free Fowlerville, Mi. Ric, that "choke" in the diesel Rabbit is a misnomer. The effect of that knob is to advance the fuel injection timing a couple of degrees, a help when the engine is cold.
I suppose it was named "choke" so that it would be familiar to people used to gasoline engined cars. Plus, it was meant to be used in the same manner as a gas engine "choke". SkyPup Guest. Diesels are not stoichometic in air and fuel at At idle, a diesel can be , at part throttle , at full throttle In fact, a direct injection engine runs with an even more greater excess of air than any indrirect engine design.
Diesels do in fact have a stoichiometric ratio, as does every chemical reaction. Skypup is correct, in that it is not the same as the ratio for gasoline engines. Combustion, whether gas or diesel, is "lean" if there is excess air for the reaction. Conversely, the combustion is "rich" if there is excess fuel. I'm sure that diesel requires more air than gasoline, simply because diesel fuel has more energy hydrocarbons to react with. The exact ration would matter to the engineer responsible for the TDI smoke map, but for everyone else, "if it's smoking, it's too rich.
This would not be caused by the mixture being too lean, but rather because there is insufficient fuel to provide power to overcome frictional losses.
In other words, if you reduce the fuel sufficiently to prevent idling, and then reduce the air which would make the mixture richer , the engine would still not idle. Higher engine temperautures can enable the engine to burn more fuel. That's why they smoke more when they're cold. I agree that there's no such thing as a diesel engine running "too lean. Particularly in a turbocharged diesel, there is a direct relationship between the quantity of fuel injected and the amount of air available to burn the fuel.
More fuel gives you more air; less fuel gives you less air. The "correct" stoichiometric mixture has a tendency to be self-regulating. The TDIs electronic control takes the calculated engine load into account, as well as a number of other factors, and makes the equation balance almost perfectly in all situations. Ignition timing is another matter entirely. Advancing the ignition timing makes a more complete burn, thus reducing smoke output and improving fuel economy and power output.
But it also increases the heat inside the combustion chamber. You CAN burn holes in your pistons that way if you overdo it! In regards to the "choke cable" in the early rabbits, it was mentioned it advances the injection timing a couple of degrees.
Makes it easier to start when cold out. So what happens after warm up, when the Choke is left pulled out? Would you get better fuel mileage or worse? And would it harm the engine? Indigo, I never left the "choke" knob out long enough on my Rabbit to figure what the effect is on fuel economy. I too have left the knob out on occasion, but never for a whole tankful!
I'm tankful for that! Isn't the reason that our TDI's smoke more at cold temperatures because the cat. Also, besides temperature, altitude plays a role in the stoichometric ratio. Diesels are less effected by altitude than gas engines, because of their "free breathing" nature.
Craig Veteran Member. Joined Apr 8, Location Kitchener, Ont. The trouble with the old manual "choke" --ignition advance on those old VW diesels is that a lot of people would forget to push them in. When they drove on the highway you would see black smoke from their exhaust. Also if your car was warm and it was pulled out the clatter would be more than normal. Even though I developed a habit of checking the knob ever few minutes when driving, there were several occasions when I forget to pull it out when starting or push it in when warm.
We are all better off with electronics! OtherCarsnAlfa Well-known member. This has to be a record thread bump. Kristofk Veteran Member.
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