Broken Crankshaft Count?

[Cknight199]

You mean to tell me that cap walk is being caused by who tunes it? Haha I didn't realize that was one of the dsp tables.

Unless one tuner is running crazy timing or something.

You just answered your own question.

I should have been more specific, he said billet mains aren't really needed anymore since they have had success using doweled stock mains, and he said tuning has a major roll in them walking.


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[Ne-max]

Tuning does play a big role. If the tuner keeps it under 1500rpms there will not be a issue.

 

[56taskforce]

I was reading were Gale Banks thinks a big contributing factor, has a lot to do with the poor intake design causing harmonics from uneven power from cylinder to cylinder. Article was saying the his Big Hoss manifold was helping crankshafts live.

 

[MSEngineering]

I was reading were Gale Banks thinks a big contributing factor, has a lot to do with the poor intake design causing harmonics from uneven power from cylinder to cylinder. Article was saying the his Big Hoss manifold was helping crankshafts live.

I didn't want to say anything, but I knew the problem wasn't casting/metallurgy since billet crankshafts broke there as well.



Fluid doesn't like making a 90 deg turn to feed the rest of the cylinders .
The ports that get the most air are those cylinders where they are breaking, precisely where the opening is making big power there increases torsional stress by generating a significant power imbalance from one cylinder and then the other crank throw pulse winding it back.

 

[Fingers]

I was reading were Gale Banks thinks a big contributing factor, has a lot to do with the poor intake design causing harmonics from uneven power from cylinder to cylinder. Article was saying the his Big Hoss manifold was helping crankshafts live.

Maybe, but I'm thinking ECM and variable timing based on the reluctor wheel.

 

[MarkBroviak]

Maybe, but I'm thinking ECM and variable timing based on the reluctor wheel.

This I can verify and got to see it for myself live last week. Tune was locked at 24* timing but it was actually fluctuating up to +/-4* even though the timing according to the log never moved. Was definitely startling to actually see this info live.

 

[countrycorey]

What is causing the timing fluctuations? Is the +/-4* fluctuation exceeding the tolerances of the hardware/software?


Corey

 

[hondarider552]

very good into on the timing fluctuations... :thumb:

Had my crank checked in my race engine last week, crack was starting to form. Not broken, but hell, I don't know what happened. Consider myself lucky. I ended up throwing the crank in the trash.

 

[Fingers]

I think it is from changes in the rotational velocity of the crank or at least the reluctor each revolution. I don't think the ECMs are compensating and "de-bouncing" the crank signal.


Here is a plot from another thread. The blue line indicates time between ruluctor pulses.

 

[NC-smokinlmm]

So the ecm isn't smoothing the crank signal? Whats the fix? Shouldn't that be just a software issue?

 

[countrycorey]

How is the reluctor changing the rotational velocity? Is it seeing the teeth longer than it's supposed to (picking up the teeth too soon or seeing it too long)?


Corey

 

[56taskforce]

Are the timing fluctuations causing harmonics or are the harmonics causing the timing fluctuations???

 

[duratothemax]

I think it is from changes in the rotational velocity of the crank or at least the reluctor each revolution. I don't think the ECMs are compensating and "de-bouncing" the crank signal.


Here is a plot from another thread. The blue line indicates time between ruluctor pulses.

Very interesting Jon!

So as far as the ECM's...

You think its because the ECM isnt compensating and applying smart "smoothing" logic to the (probably not perfectly clean) raw signal from the CKP sensor? So when the RPM shifts up/down, the ECM is constantly chasing its tail adjusting actual timing, so to speak? Rather than taking an "average" CKP/RPM reading over a specified duration of time?

And then on the 01-05 trucks, we have the FICM in the equation too...when you think about it, its a pretty complex series of steps that has to happen correct?

1...ECM reads raw CKP signal from the sensor, processes it.

2...ECM turns that raw signal, does 'stuff' to the signal, turns it into a "replicated" smoothed square-wave RPM signal, which it then outputs/forwards to the FICM, so the FICM knows real-time engine RPM (as opposed to only getting RPM over "slow" 250k CAN)

3...ECM calculates actual injector pulsewidth, timing, etc based on what the tune says

4...ECM sends those commands to the FICM via the 8 discrete "injector control" wires

5...FICM receives signals, processes them

6...FICM fires the injector

I dont know enough about the actual hardware/software involved here, but between all of those steps and messages/signals flying around, it would seem there are quite a few areas of potential "screw ups"?

And onto the FICM...what exactly do we know about it? Does it do any extra processing of the injector-control signals? Does it have the ability to make any adjustments of its own? Is there any additional fuzzy-logic that happens within the FICM before it actually fires the injectors?

What is the first bottleneck in the entire system? ECM processing power? FICM processing power? FICM driver circuitry? Inaccuracies of the CKP sensor/wiring/signal noise? Injector solenoids themselves?

As far as what the ECM reports for a main injection timing PID to the scan tool...im sure that value is buffered, and maybe just a "roughly X* is desired right now" PID, and not a "this is the actual timing that the ECM is commanding at this instant" PID?

Given the sloowwww 10.4k Class 2 bus that 01-05 ECM's present scan tool data on, I would guess the ECM just broadcasts a "general/desired" value?

Has anyone plugged in a CAN datalogger on an 01-05 truck, and then compared it to what EFILive shows in logs over Class 2 bus?

Does this margin of error (IE, the actual timing jumping around) increase with RPM? Are the timing +/- fluctuations random on each crankshaft revolution, or is there a visible trend of certain times when the actual timing is constantly (>500milliseconds or so) + or - the "desired" timing?

Ben

 

[valleyduramax]

So if you take all 8 cylinders and have a single combustion event in each, or in other words a full cycle, does the timing vary a total of 8 degrees if comparing 2 cylinders? If that is true and then you combine the info on non equal cylinder charge according to Banks, would this be a good indicator of why the cranks, regardless of either stock or billet aftermarket break in the same place more often than not? Just trying to wrap my head around this.

 

[Dave c]

Timing variations are cause from injector contribution control.

 

[PACougar]

Timing variations are cause from injector contribution control.

If you're going to pretend to not be someone else, at least have someone else structure your sentences.

 

[S Phinney]

Has anyone broken a crank with the alt firing camshafts now?

 

[mike diesel]

Has anyone broken a crank with the alt firing camshafts now?

People will try and tell you there have been but when you ask when, how, where, who...they can't/wont say or they "heard it through the grapevine" and can't backup they're statement.

 

[PACougar]

People will try and tell you there have been but when you ask when, how, where, who...they can't/wont say or they "heard it through the grapevine" and can't backup they're statement.

Mike didn't you know it's super secret squirrel stuff when one breaks with a Alt cam. :roflmao:

 

[Ne-max]

People will try and tell you there have been but when you ask when, how, where, who...they can't/wont say or they "heard it through the grapevine" and can't backup they're statement.

Also a issue is many guys are running a alt firing cam on a crank that had a standard firing before. I think that might be a factor.