What Are Mechanics Of Timing Knock

[JJPage]

I have asked this similar question before, I presently have a 0336 code which TST basically says to ignore. Anytime I have the TST above 1/1, I get quite noticable timing knock, the higher the setting the louder the knock.

Can anyone explain just what is actually happening internally to cause this and how harmful is it.

I would like to add a Rokktech crank sensor and maybe the tone ring mod but I am already paranoid with the knock that I have.

Mark @ TST told me he would reflash my box to eliminate the code but I do not want to sacrifice any performance. Any light that someone can shed on this would be appreciated. Have a Merry Christmas.

 

[JEpling]

I have the same problem with my tst on my 05

 

[JJPage]

Thanks for the reply, I guess I'm just asking the wrong question. I figured someone would know what is actually happening when the timing is advanced to cause the knock.

 

[Matt400]

I still understand gassers better in this category but will give your question a shot. .



Advancing timing will effectively increase cylinder pressures in a diesel and its those higher pressures that contribute to better mpg's but only to a point.

The higher pressures can also contribute to engine knock, I found a good statement at the bottom of this page



IMO I would not do the tone ring or even the roc sensor with a TST because its my understanding that TST uses the maximum timing you would ever want to run so adding in even more would only compound the trouble.

I doubt TST took into consideration users would try this.



IMO smooth is better so any box that makes it knock is not a good thing.

 

[JJPage]

Thanks Matt, I believe I will send my box back to TST for reflashing, as the knocking is very loud. It started out doing it just when cold but now all the time, I was thinking maybe a bad sensor but if I turn the box to 0/0 no knock.



TST has a by-pass plug available now so I do not have to remove the harness.

 

[JStieger]

When I ran the Juice on my truck it caused my truck to ping and rattle a lot more than the TST I run now. Maybe the Juice levels are fixed timing, whereas the TST is more dynamic?? Also, increasing fuel pressure like for the 03-04 Juice is in effect like advancing the timing anyway (same amount of fuel in less duration due to higher pressure).



In any respects, one has to give credit to these box manufacturers for being able to do all these ECM "fooling" changes over and above what the ECM dynamically does depending on load and temperatures!

 

[ata]

All gas and diesel engines start to burn there fuel charge before the piston is at the top of there stroke. (Top Dead Center TDC) So Max cylinder pressure is reached just after TDC. So when you Advance the timing to much your getting to high of cylinder pressure before the piston reaches TDC which is causing the knocking noise. Is it hard on the engine YES it's to the point of trying to make the engine run backwards when it's running forward. So lets start from the top it's hard on Head Gaskets,Pistions,Wrist Pins,Rods,Rod Bearings. Crank Shaft and Main Bearings. If your Pulling a Sled or Racing the engine it' a good thing because Advaced Timing does make power. But it reduces your engine life.

 

[grfraz]

I know a little more about gasser's myself but I believe the same thing could happen with a diesel;



In the gas engine fuel is injected/aspirated (depending on fuel delivery system) to the combustion chamber and compressed to a point were the spark plug fires creating the explosion that drives the piston back to the bottom of its cylinder. This is generally pretty close to top dead center, timing is advanced so that the fuel will have more time to completely combust. Timing can be advanced to the point that the engine can kick back on start up (try and spin backwards), this used to brake a lot of oil pump drive shafts. If timing is retarded (after top dead center) then the fuel is not burned in the combustion chamber and the engines power is compromised and because it doesn't burn in the combustion chamber it has to burn in the exhaust manifold causing them to get really hot. I have seen them so hot that they appear translucent.

timing knock

So, in the gas engine this is called pre-detonation, meaning that the timing is advanced to the point that fuel is being injected and ignited by a hot spot inside the cylinder. Yes it is harmful in these (gas) engines, on the pistons, pins, rod bearings cylinders gaskets, just as mention above.



The diesel engine does not have spark plugs, they fire because of heat of compression:



The diesel piston is driven to the top of its cylinder compressing all of the air that was drawn in during the intake phase, this compression heats up the combustion chamber so then when the fuel is injected at the right point in this phase there is enough heat to cause spontaneous detonation of the fuel. With the advances in diesel technology over the years it has been discovered that compressing the fuel and delivering it at higher pressures will cause the diesel fuel to become more volatile and make ignition more complete. However, just as in the gas engine, if the timing is retarded (after top dead center) the fuel is not consumed in the combustion chamber but in the exhaust manifold, causing very high EGT's and this is why you guys with the timing boxes are experiencing lower EGT's.

With these newer engines and their multiple injections of fuel at higher pressures (2 small pre-injections and then the final injection), I believe advanced timing can cause the same phenomena that the gas engines experience. As for damage, the fact that the these engines are built so rugged I am not sure if this will cause damage to them or not.



experiment: take a small amount of diesel fuel in a pie plate (small amount just coat the bottom of the pan) and try to light it with a lighter, you'll find it want ignite easily. Now, take the same lighter and heat the bottom of the pie pan until you see the diesel begin to evaporate and expose those vapors to the lighter, you'll see a big difference in the ignition.

Diesel becomes more volatile as it is heated.

 

[JJPage]

OK, going to try one more thing before sending my box back. If I understand correctly there is some slack to be found in the tone ring, I will loosen and try retarding(counter clockwise) my timing. My TST works so nice otherwise that I hate to change anything. Thanks