losing mm3 at 121mph?

[sweetdiesel]

Ive noticed from my logs that at 121mph my mm3 drops?
Nothing in the tune that i can see should be dropping?

Its done this on the street and the track Drops to like 80mm3


Just wonder if anyone has ever seen this?

 

[duratothemax]

simon is this on the LB7 or LLY?

LLY's are notorious for getting screwy above 3,100rpm and ~105mph. The main rate jumps all over the place as it tries to defuel for some reason that NO ONE has figured out.

 

[paint94979]

simon is this on the LB7 or LLY?

LLY's are notorious for getting screwy above 3,100rpm and ~105mph. The main rate jumps all over the place as it tries to defuel for some reason that NO ONE has figured out.

It's an LB7... he runs a Road Runner ECM. My LLY was doing this Simon my problem was in the torque limiting table. Maybe a second set of eyes would help?

 

[McRat]

Is the power actually falling?

Pulse width still correct?

Some of the PID's will "freeze" at 79.7mm IIRC.

But yes, there are limiting tables that can kick in. What is your RPM at 121?

Also, injector overlap first nailed us at 120 mph, IIRC, but if your PW is under 2900 it's not that.

 

[duratothemax]

It's an LB7... he runs a Road Runner ECM. My LLY was doing this Simon my problem was in the torque limiting table. Maybe a second set of eyes would help?

Im NOT gonna go into this again. Ive had 64 sets of eyes look at my tune, and another 128 send me tunes that they were oh-so-confident ("ben you're an idiot, theres something wrong with your tune! my truck doesnt have this problem") would fix my trucks odd defuel problems. Guess what. Nope. None of them worked.

ben

 

[sweetdiesel]

mm3 drops from 110 to 68mm3, The PW is normal for the referenced mm3
Rpm is 3700 going to 3800

Fuel rail pressure is des 179 actual 177mpa

Maybe its just the lb7 cp3s loosing its jam??

max pw in the tune is only 2700 AND it feels like it looses power it still logged to 128mph but it wasnt as fast

 

[McRat]

Im NOT gonna go into this again. Ive had 64 sets of eyes look at my tune, and another 128 send me tunes that they were oh-so-confident ("ben you're an idiot, theres something wrong with your tune! my truck doesnt have this problem") would fix my trucks odd defuel problems. Guess what. Nope. None of them worked.

ben

So your advice is for him to never ask anyone for help?

Lighten up.

 

[LBZ]

Could it be a limiting table in the trans tune?

If your holding rail, the CP3's can't be the issue can they??

 

[sweetdiesel]

I dont see anything in the TCM that relates to fuel VS speed?

 

[LBZ]

I can't look at any tunes as I'm at work on my company laptop and I'm not sure about the 5speed trans tables but :

What about rpm?
Could something be limiting fuel maybe because of your rpm? TLIQ? TBIQ?
It's just that you have RP so you got the fuel, but it's backing off the mm3 right?

I dunno for sure, I can barely keep my lawnmower running let alone tune these trucks but I just recall when I was messing with my trans tune I had the same thing happen on the 3-4 and the 4-5 shifts when I ran my tow trans tune with my race tune-which was shifting at 3800rpm and it was defueling badly before it would shift. For some reason TBIQ related tables was my problem IIRC.:dontknow:

 

[JoshH]

Simon, are you sure it's speed and not RPM related?

 

[sweetdiesel]

simon is this on the LB7 or LLY?

LLY's are notorious for getting screwy above 3,100rpm and ~105mph. The main rate jumps all over the place as it tries to defuel for some reason that NO ONE has figured out.

LB7
Tune does what it is suppose to do Except at that speed
If it was RPM related it should do this earlier in the tune and it Doesnt
the numbers dont bounce around, they just follow the referenced fuel.

How about rpm?

nothing changes from 2800 to 4800 that should allow a defuel

 

[sweetdiesel]

Simon, are you sure it's speed and not RPM related?

are you saying tuning or actual hard parts need changing?

Everything in the tune is maxed

 

[LBZ]

That is 5th gear at that speed right?
What is your rev limiter at in the trans and ecm tunes? The same?

It just doesn't add up.....

 

[LBZ]

are you saying tuning or actual hard parts need changing?

Everything in the tune is maxed

I don't see how but what about those tires being smaller? Just spit balling, but what about changing your tire size pulses per mile in the tune. Tell it the tires are smaller than they are.

 

[sweetdiesel]

That is 5th gear at that speed right? 2nd gear
What is your rev limiter at in the trans and ecm tunes? The same?
ecm is 5000 TCM doesnt have one that i know of?

It just doesn't add up.....

Answers in red, Sarcasm in bold

 

[LBZ]

Answers in red, Sarcasm in bold

:rofl:
Sorry, I'm just not used to seeing those rpm's in 5th gear you short tire'd peckerhead!!

 

[sweetdiesel]

Looking at some older logs it does it also

I cant be the only one this has happend to?

I wonder if i command 190mm3 if it would help since it starts to drop and the mm3 falls maybe it would take longer to drop to the 60-70mm3???

Its not a rail problom since the old logs show commanded 165mpa and actual is 180mpa When i run a 2400pw

 

[JoshH]

are you saying tuning or actual hard parts need changing?

Everything in the tune is maxed

No, I'm saying is there maybe something in the tune, maybe even something you can't see, that is cutting fuel at higher RPM. Have you tried holding 4th out to the RPM you are seeing in 5th to see if it does the same thing?

 

[sweetdiesel]

No, I'm saying is there maybe something in the tune, maybe even something you can't see, that is cutting fuel at higher RPM. Have you tried holding 4th out to the RPM you are seeing in 5th to see if it does the same thing?

No, but that is a good idea.