Tuning school

[Derek@Vision Diesel]

Bill is still awake -- only to call customers to do ECM rollbacks. He actually never went to bed last night... just got about 30 minutes of snoozing in his chair before 9AM this morning. As soon as he's done with this last customer, he's going to sleep, but I know that he's planning on touching base with you, Derek. We talked about it in the office today.

Don't get the wrong idea at all, we are in no hurry i am glad you stay busy!!

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[ken6881]

I have a question been working on some tunes for my truck(stock injectors hpop turbo) and overall truck runs great but when you start the truck it puffs black smoke. It starts quick doesn't surge upon starting just a puff a smoke. I tried lowering the cranking fuel quantity but doesn't seem to have helped.

Any thoughts to try?

 

[Gearhead]

I have a question been working on some tunes for my truck(stock injectors hpop turbo) and overall truck runs great but when you start the truck it puffs black smoke. It starts quick doesn't surge upon starting just a puff a smoke. I tried lowering the cranking fuel quantity but doesn't seem to have helped.

Any thoughts to try?

Glow plugs work? Honestly, when tuning change one thing at a time and as little as possible then test again is the best approach for beginners.

 

[ken6881]

I haven't tested them but it starts quick and none of my other tunes seem to do it so I assume the glow plugs work. I have compared them and nothing in what looks like it would affect Idle/starting ranges appear different.

 

[Gearhead]

If you compare to one that doesn't have the issue what has changed?

 

[ken6881]

pulse width(but nothing in the 0-8mg range)
accelerator position table--but not at 0 throttle input
fuel limiter for smoke control-- don't see that affecting starting
injection timing--I added a little in the higher fueling range to clear up some smoke at wot again don't see it affecting starting.
desired icp- not changed at low rpm and low mass fuel
ipr duty cycle--again no change low rpm or mass fuel
ICP duty cycle max(scaler)--upped to 85%
cranking fuel --Lowered it about .8mg to try to cure this problem
trans shifting adjusted but should be unrelated to this.

I am thinking about just starting back with a stock tune and changing one table at a time tell it comes back. I was having low icp issues that the reason for a lot of the icp duty cycle changes trying to cure that. Now I think it was some poor oil that the previous owner of the truck was running when I changed the oil it came out thin as water.

 

[Gearhead]

Ipr duty cycle doesn't reference mass fuel or rpm in an axis. I've just always thought of it as regulator bypass flow where 0 is all the pump will give and none bypassed.

 

[ken6881]

Ipr duty cycle doesn't reference mass fuel or rpm in an axis. I've just always thought of it as regulator bypass flow where 0 is all the pump will give and none bypassed.

Your right it doesn't I don't know which table i was looking at when I typed that.

This rises another question. On my table ipr duty cycle decreases as fuel flow increases. Which makes 100% sense closing the valve as you need more fuel. But as icp increases so does the duty cycle which to me is backwards of what it should be doing. Should it not be closing the valve to hold more oil in the high pressure side of the system?

Thanks four your help on this.

 

[POWER-STRUCK]

i think you guys are thinking backwards on IPR duty cycle but i guess it depends who made your templates

 

[2000wa250]

DC should increase as fuel increases. DC is time on not time off. Time the regulator is closed therefore can allow more pressure to build

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[POWER-STRUCK]

typical duty cycle paramter on a stock truck is 11% at idle and 64% under full load

 

[ken6881]

DC should increase as fuel increases. DC is time on not time off. Time the regulator is closed therefore can allow more pressure to build

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This was my original understanding of it as well.

Where is fuel flow measured?

here is a screen shot of a stock tune ipr duty cycle.
Why is it they lower ipr duty cycle with higher fuel flow or is the fuel flow whats being bypassed?

 

[POWER-STRUCK]

thats not fuel flow thats is ipr DC% and causes more icp pressure, more pressure will give more flow but pulse width controls on off time for the injectors

 

[Gearhead]

Oil flow is what the ipr is trying to contend with. More duty cycle means more that the ipr is holding back from bypass and the more making it to the injectors.

 

[ken6881]

thats not fuel flow thats is ipr DC% and causes more icp pressure, more pressure will give more flow but pulse width controls on off time for the injectors

I know its ipr dc% but what is the fuel flow axis on the left hand side and how is it measured?

 

[907DAVE]

In my definitions its labeled as "regulator flow".

 

[ken6881]

that makes much more sense yeah my definitions are terrible. You cant graph anything because the limits on the graphs are way out of range of anything useful.

 

[POWER-STRUCK]

my guess would be that it is relative to mass fuel desired

 

[907DAVE]

that makes much more sense yeah my definitions are terrible. You cant graph anything because the limits on the graphs are way out of range of anything useful.

You can adjust normalizers to get thing into a useful range, and with the new version of Minotaur you are able to change your definitions also.

 

[ken6881]

That is the thing I am not running minotaur.