Why are some diesels loud at idle and some quiet?

 

It is mostly due to knock...

The newer diesels are much quieter (than the older DI ones), because injector response times have got incredibly quick, and you can have multiple injection cycles in one power stroke.

A lot of the noise is a by product of rapid temperature changes, and the compression ignition explosion. You will notice they are all louder in colder temps.
You can make a gasser sound similar if you run it on regular - and give it 30deg spark advance

IDI's aren't as loud, because its more of a gradual explosion, than a sudden injection of fuel at full compression, and BANG.

Also - the PSD, with its HEUI system, adds some of the noise to the engine as well... hello injector cackle

 

I just remember in my original program the idle was quiet.
Then it got loud with the reflash.
My brothers '06 is so loud we have to stand away from the truck to hear each other talk.
Will Ford ever go back to what they had when the idle was quiet?
I mean I know its a diesel and makes noise, and I love the sound of a diesel but I sure miss the quiet idle.

 

Pilot injection is a great way to quiet diesels down, especially at idle. Your original flash probably had pilot injection, as Ford used this in the early 6.0's. I don't specifically recall the reason for getting rid of it. I've heard 2 theories: 1) people wanted the loud diesel idle; 2) it caused injector problems on the early injectors.

-blaine

 

2) it caused injector problems on the early injectors.

It caused Injector problems on all the injectors... but the problems only appeared in the first few thousand miles (if they were going to appear), I think there are some 6.0l owners still in the 6.0l forum with pilot injection...

 

Is pilot injection something that can be programmed in to the trucks computer. Or does it require changing all the injectors themselves?

 

Here are several other easy mods/fixes for PSD engine noise.

1. In-tank mods (hutch and harpoon) - increase injector life in addition to reducing noise.
2. Cackle-Cure Kit (fuel rail crossover connections to balance fuel rail pressures and flows) - also increase life, but mainly for injector #8, and reduces engine noise.
3. HPX mod (high pressure oil rail crossover connection) - balances oil pressure across the heads, reduces engine noise
4. 5w40 synthetic oil - really provides a nice quieting effect and makes cold weather starts much easier on the engine and starter.

 

5. run B10, B20 etc. biodiesel, makes for a very smooth running truck, at idle not so much of noise decrease though for me. Just had to throw that in for grins.

 

It can't be programmed in only programmed out.
If the truck doesn't have it now, it will never have it.

If the truck has it now - don't go within a 5mile radius of a Ford dealership - for fear of them re-flashing the computer.

 

I think with the aftermarket programmers they can put it back in if you wish to go that route

 

I am not a diesel guru but I was told on later model diesels have indirect injection system causing them to louder and newer models have direct injection that is a whole lot quieter any truth to this?

 

For a start - WELCOME!!!


Indirect injection is actually a lot quieter than direct injection. But its no where near as efficient.
In 94 Ford went from Indirect Injection (IDI) to the Powerstroke, which is direct injection.

 

thanks for the welcome!!

and for the clarification.

 

You would be correct, however many tuners recommend against using it.

 

I know the SCT has the capability of reprogramming it back in but some of the 03 and 04 trucks dont have enough 'computer space' (for a lack of a better term) to do it. Why do they recommend against it?