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Discussion Starter #22
Hey Ricky,

No solution yet....
Since last week, i have swapped ECM, TCM, Fuse block, MAP, MAF, IAT.... All from good working LBZ trucks...

I also found a local, bone-stock LBZ and was able to take it for a drive and watch some parameters.
The "Transmission requested torque" behaves exactly like yours and mine, so i am assuming that is normal...
It only shows a value, (Approximately 40-60 Nm) when shifting gears....
I have not found anything to confirm this, but i suspect this is the transmission requesting a decrease in torque while it shifts to the next gear?
It seems the harder the acceleration, the larger that value shows. Again, only for about a second while it makes the shift, then returns to zero.
I don't think this is my problem....

The other parameter that i thought could be my problem turns out to be "normal" as well...
Under transmission data, there is a parameter called "GEAR RATIO". my truck reads 8:1.... turns out this other truck also reads 8:1..
Not sure which part of the drive-train is 8:1, but apparently that's normal as well...

Driving around the bone-stock LBZ, aside from having much more acceleration and power, it does smoke (normal amount) a under WOT. (Again, bone stock exhaust)
My truck smokes zero. Not even while "brake torquing" at WOT.

For whatever reason, the engine is just not getting the fuel it needs.

My truck has a lift pump supplying 13 psig to the CP3, and the rail pressure at WOT holds at ~29,000 psi.., slight decrease each shift.

Now, since i've had my engine running, (last 6 months), i noticed that whenever the key is on, and for about 2 minutes after the key is off, you can hear a very noticeable "HUMM / BUZZ" coming from the CP3 / Fuel pressure regulator.
I confirmed that its the Fuel pressure regulator making this sound because when i electrically disconnect it, the buzzing goes away...
When i turn the lift pump OFF, and press the manual primer pump on the fuel filter housing, the tone of the buzzing changes.

I did NOT notice this sound coming from the bone-stock LBZ that i test drove, and can not find any information about this buzzing online.

Can anyone else confirm if their LBZ buzzes / humms key on , engine off?
Perhaps the Fuel pressure regulator is the problem? yet the rail is matching and holding desired fuel rail pressure.

Thanks for reading,
-Alex
 

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Discussion Starter #23
UPDATE: August 11, 2020
Over the weekend i replaced the FPR (fuel pressure regulator) on the back of the CP3.
The new one does not "buzz" / "hummm" like the old one, but did not make a difference as far as fixing the lack of power...
I then replaced the fuel pressure relief valve with a PPE "race valve". (the valve at the end of the drivers side fuel rail. - made no difference either...

The first photo is a screen capture of a WOT launch from stop, showing fuel rail pressure.
You can see at idle, its at about 30,100 kPA ( 4360 psi)
Through the range of first gear, it only reaches 129,000 kPa (18,700 psi.
You can see the pressure drop slightly as it shifts, then right to 182,000 kPa (26,400 psi). You can see the shifts in the drop in pressure.

The second photo shows rail pressure, engine at idle, with the FRP plugged in, unplugged, and again plugged in.
At idle, plugged in reads 30,100kPa (4,360 psi)
At idle, un-plugged it spikes to 129,000 kPa (18,700 psi) - Seems low?

I was expecting to see the full MAX 29,400 PSI when i unplugged the FPR.

Perhaps the CP3 is the problem?

Only problem is, if the CP3 was not able to keep up to the demanded requested fuel pressure, you'd think it would throw a code / DTC alarm.
When i track the demanded vs actual, it matches pretty bang on...

Any thoughts?
Thank you,
-Alex
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Discussion Starter #25
Hi Mike L,
I am at a dead end as far as finding a solution.
Can you elaborate on the bad torque converter sprag theory? Is there a way to check / test this?
Thanks,
-Alex
 

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Discussion Starter #26
Afternoon All,
Thought i would give an update and perhaps brainstorm some new ideas...

In the last 3 weeks i have tried a lot, without results.

After changing the FPR and FPRV, (did not solve any problems) i bought and got set up with EFI Live V2 to aid in diagnostics.
I was able to record some data logs of dead stop to WOT (wide open throttle) as well and (brake torques) (wont spin tires though)....

Not that i'm an expert, but i cant see anything obviously wrong as far as the data goes.
Fuel pressure looks good and matches requested. Same with turbo vane position.

Is there a place in this forum that i could post these data logs for review?
-Alex
 

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Afternoon All,
Thought i would give an update and perhaps brainstorm some new ideas...

In the last 3 weeks i have tried a lot, without results.

After changing the FPR and FPRV, (did not solve any problems) i bought and got set up with EFI Live V2 to aid in diagnostics.
I was able to record some data logs of dead stop to WOT (wide open throttle) as well and (brake torques) (wont spin tires though)....

Not that i'm an expert, but i cant see anything obviously wrong as far as the data goes.
Fuel pressure looks good and matches requested. Same with turbo vane position.

Is there a place in this forum that i could post these data logs for review?
-Alex
Let's keep your trans thread on topic and rule things out here with responses to your trans diagnostics.
You can post your engine data logs in the engine thread you started:

(y)
 
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Hi Mike L,
I am at a dead end as far as finding a solution.
Can you elaborate on the bad torque converter sprag theory? Is there a way to check / test this?
Thanks,
-Alex
I bet Mike is on the right track. He's a professional, I'm not. But... It means the torque converter isn't working correctly/optimally. The stator can spin freely in both directions instead of only one. BL: if that's it, you can't fix it. Must be replaced. Mike is super helpful. I'd find his number at Inglewood Transmission and give him a call.

Roz
 
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