Well, does anyone have one or know of someone that has either EFI or a Tech2 tool that I can have someone scan my truck? I live in Hanford, Ca.
JLew
JLew
Help Mr. Pat McRat!
- Thread starter screaminjlew
- Start date
There is a part of the fuel pulse or pressure table that is confused around 2 mph. I am pretty sure it is a transition issue when going to idle mode.
I no longer have the issue, as none of my tables are stock any longer. I am very impressed at how a new pressure table fixed a lot of the trucks lousy response habits.
I no longer have the issue, as none of my tables are stock any longer. I am very impressed at how a new pressure table fixed a lot of the trucks lousy response habits.
It's actually pretty easy to track it down by logging the event, then playing it back on the pulse table, B0721. At idle fuel pressure of 30 Mpa, the table flairs to much, causing an overpulse IIRC. IOW, a feedback oscillation around idle rpm set point. IIRC flattening the table some resolved it.
Sorry, this thread dropped off my radar.
Datalog commanded vs. actual rail pressure (and other "standard" PID's) and post it up.
If the actual is significantly higher, you can either rescale the fuel pressure regulator, or just do as I do, which is to lower the rail pressure in the offending area.
Datalog commanded vs. actual rail pressure (and other "standard" PID's) and post it up.
If the actual is significantly higher, you can either rescale the fuel pressure regulator, or just do as I do, which is to lower the rail pressure in the offending area.
I Agree...FPR. Its prolly gettin a little sticky, best to just replace it with a better one if you do Mine started the "idle down chug" when i modded my CP3 and exacerbated it more yet with a lift pump. It dosnt really bother me, only does it coming to a stop. I'll replace my FPR when it gives up. I had mine apart and it had some scoreing on the slide valve, no doubt thats the problem, IMO
Mine started the "idle down chug" when i modded my CP3 and exacerbated it more yet with a lift pump. It dosnt really bother me, only does it coming to a stop. I'll replace my FPR when it gives up. I had mine apart and it had some scoreing on the slide valve, no doubt thats the problem, IMO
Rescale the fuel pressure reg? Can this be done with the "current" table?
Also my actual is only about several hundred psi more than the desired.....would it be worth it to me?
Also my actual is only about several hundred psi more than the desired.....would it be worth it to me?
Loping surging, whatever you want to call it, could be from a FPR, but in my LLY, I fixed it with some reshaping IIRC. I am going from memory so bare with me.
In idle mode, pressure is fixed, and idle rpm is maintained by adjusting mm3, or pulse. At the idle off speed (I think it is 2 mph on stock tunes) then pressure becomes a variable.
Here is what i referred to earlier. I highlighted around the area that causes the problem I noticed, flattening it out some removed the idle oscillation.
Again going from memory, and mine has been abused.
In idle mode, pressure is fixed, and idle rpm is maintained by adjusting mm3, or pulse. At the idle off speed (I think it is 2 mph on stock tunes) then pressure becomes a variable.
Here is what i referred to earlier. I highlighted around the area that causes the problem I noticed, flattening it out some removed the idle oscillation.
Again going from memory, and mine has been abused.
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