Question: Pilot timing considerations

[xcablb7]

The problem with tuning the maf limiting table is that if you hit a limit while driving or towing it throws you in limp home mode, very frustrating and time consuming, also to many variables to try and figure out for me

 

[[email protected]]

On the lly's there is a maf limiting table that sets a Max commanded fuel value for certain airflows, maybe its different on a lb7 but I don't see why it would put you in limp mode?

 

[SSchmi5519]

On the lly's there is a maf limiting table that sets a Max commanded fuel value for certain airflows, maybe its different on a lb7 but I don't see why it would put you in limp mode?

Its when the expected MAF values don't agree with the actual MAF values that it wants to throw the code. You can increase the number of errors so that this doesn't happen.

 

[Mike_S]

However, i dont see what MAF limiting tables have to do with pilot injection...yes they are great for limiting smoke, and workquite well for it, however the situation i have is slightly different than wht you are thinking. The smoke im trying to eliminate is continuous, at speed, and above 25% or so throttle. The MAF limiting tables wont really help here as the turbo is already at the boost its going to create and the airflow isnt going to change much.

 

[Kspen90]

However, i dont see what MAF limiting tables have to do with pilot injection...yes they are great for limiting smoke, and workquite well for it, however the situation i have is slightly different than wht you are thinking. The smoke im trying to eliminate is continuous, at speed, and above 25% or so throttle. The MAF limiting tables wont really help here as the turbo is already at the boost its going to create and the airflow isnt going to change much.

As i stated above i know nothing about tuning but the problem your having seems to be somewhat similar to when a gasser isnt getting enough spark, so i would think you problem must be in the pilot injection. I would think either #1 your not spraying enough during the pilot to have a healthy enough fire to ignite the main injection event or #2 You are spraying too much at pilot to combust at pilot timing and cooling the cylinder wall kind of like the issue with bigger injectors spraying larger droplets than stock that McRat talked about in a thread a few months back. But I may be waaaayyyyy out in left field. Hope my $0.02 will jar something loose in your head to help you figure it out:thumb:

 

[[email protected]]

As i stated above i know nothing about tuning but the problem your having seems to be somewhat similar to when a gasser isnt getting enough spark, so i would think you problem must be in the pilot injection. I would think either #1 your not spraying enough during the pilot to have a healthy enough fire to ignite the main injection event or #2 You are spraying too much at pilot to combust at pilot timing and cooling the cylinder wall kind of like the issue with bigger injectors spraying larger droplets than stock that McRat talked about in a thread a few months back. But I may be waaaayyyyy out in left field. Hope my $0.02 will jar something loose in your head to help you figure it out:thumb:

I think your right about too much fuel cooling the cylinder. I think the heat absorbstion of injected fuel can play a big part in timing needs.

 

[SSchmi5519]

However, i dont see what MAF limiting tables have to do with pilot injection...yes they are great for limiting smoke, and workquite well for it, however the situation i have is slightly different than wht you are thinking. The smoke im trying to eliminate is continuous, at speed, and above 25% or so throttle. The MAF limiting tables wont really help here as the turbo is already at the boost its going to create and the airflow isnt going to change much.

What color smoke?

 

[Mike_S]

What color smoke?

Light black/brown. Some white at idle but im not worried about that, just havent gotten around to fixing that yet.