LLY: cracking injector bodies

[McRat]

Bandimere is whole nuther ball of wax. We could easily spool at 1000', but when we arrived at Colorado, we couldn't even get the truck to light the charger. We borrowed some nitrous parts or we would not have been able to run. We ran faster and quicker at 1000 feet on fuel only, than with a nitrous shot added at Bandimere.

 

[juddski88]

Because it makes sense. Pilot injection we shut off before the rpm that full pressure is commanded. So pilot is off or else we would see it in the log right? Even if it was evident just by seeing pressure loss. You are certainly right about the oddball configuration, but rail pressure is rail pressure, the limits of injector bodies May not be consistent frok body to body, but nobody can deny there have been failures due to pressure. Talk to any of the best fuel injection shops in the country, pump builders, etc and they will tell you they have had failures from pressure spikes. I get that it happens. But I am proactive. Always have been, always will be. I dint have the interest in driving 36hrs to an event to crack another injector....do you?

not to start an argument tim but....how can you definitively blame this 100% on "just because running too high pressure" when your whole fuel injection setup is a complete through-and-through wild card.

You're feeding the injectors double the voltage (LB7 FICM driving LLY injectors).

You're running a completely unique/wild/abstract tune (because thats what it needs to even idle, let alone make big power, as we've found over the past year or so of playing with tuning on it)

You're running an LB7 ECM. LB7 and LLY ECM's definitely run pilot injection differently, and LLY ECM's control the ramp-in and ramp-out of pilot injection more precisely. LB7 ECM's also generally process things a little slower, so fuel pressure control PID/feedback loop is going to be slower.

You've got a completely custom wiring harness, and IIRC the injector-control wires are the same size as all the other wires, whereas the factory uses much thicker gauge wire from the FICM to injectors. (maybe the longer wires changes capacitance to the point where it screws with things? I dont know)

But basically......in my opinion you really cant definitively write this off as "such-and-such problem caused this" considering your truck and how its built/configured/wired/tuned. I know it feels comforting to "have a definitive answer and smoking gun" to problems like this........but in this case, there really is neither......

 

[juddski88]

Bandimere is whole nuther ball of wax. We could easily spool at 1000', but when we arrived at Colorado, we couldn't even get the truck to light the charger. We borrowed some nitrous parts or we would not have been able to run. We ran faster and quicker at 1000 feet on fuel only, than with a nitrous shot added at Bandimere.

Dont get me wrong, I expected to run better down here, heck we even got the turbo to light nicely in Aurora. But 600 ft more elevation killed it. Micheal really came through for us too.

 

[juddski88]

Also the people I know that have had injector body issues are pretty extreme, 3 stroker cp3s goin wide open to nothing will cause extreme spikes. I haven't had a problem with 2 stroker pumps, and high pressure but my junk is lb7

you guys command full 180mpa?

 

[MACKIN]

Dunno, I've run a few thousand passes, over 200,000 miles, over 100,000 towing, on 3 trucks programmed to "kill" on pressure.

Guess it happens, I'm just not seeing it a lot like turbo boots, speedos, wheelbearings, pistons, rods, etc.

If my setups were popping injectors on a routine basis, I'd be doing something. But one failure in 7 years for us is not enough to generate a MTBF.

NOTE: LBZ+ injectors have thicker bodies.

Also, be aware that by now, hundreds of people are running KILL fuel pressure. All the tunes I sent out were maxed, and I didn't get much feedback about cracking.

When the LB7's came out, everyone blame pressure boxes on the high failure of LB7 injectors. Later on, they found it was the injector itself that was the issue, at any pressure.

I remember all of that but isn't he running or cracking LLY injectors? I thought he did the swap LB7 to LLY conversion.Or am I just misinterpreting your point ?

 

[RPM Motorsports]

that's what everyone tells me, but without my glows ive never been able to start this truck with either motor, and this one has higher compression! cranking injection quantity is still stock, maybe that needs a tweek? i dont know. it can be 100 degrees out and if the motor is cold it wont start. needs to be 110 degrees ECT before the truck runs clean

Add 35-40% to the cranking qty, and it will fire right up first time . I fought that one for a while with the swaps too!

 

[duratothemax]

Because it makes sense. Pilot injection we shut off before the rpm that full pressure is commanded. So pilot is off or else we would see it in the log right? Even if it was evident just by seeing pressure loss. You are certainly right about the oddball configuration, but rail pressure is rail pressure, the limits of injector bodies May not be consistent frok body to body, but nobody can deny there have been failures due to pressure. Talk to any of the best fuel injection shops in the country, pump builders, etc and they will tell you they have had failures from pressure spikes. I get that it happens. But I am proactive. Always have been, always will be. I dint have the interest in driving 36hrs to an event to crack another injector....do you?

Ok im not going to argue any more, its your truck. If you think its only pressure alone and absolutely nothing to do with your bizarre setup of mismatched ECM/mismatched FICM/completely custom wiring harness/unique tuning, then Im not going to argue that.

But im also not about to go retune every single one of the dozens upon dozens of LLY's ive run with higher pressure back down to stock pressure. Schulte's injectors are a pretty good amount bigger than yours, his rail pressure sensor is rescaled properly, and he runs 180-185mpa. He puts a lot more miles on his truck than you do on yours and when he sent his injectors out to be checked when we rebuilt the motor last, they all came back fine.

My truck has been tuned with efilive longer than 98% of other duramax's out there (original beta tester, december 2005). I dont remember how many miles were on the truck when we first started beta testing, but it probably wasnt more than 15,000-20,000 miles. I have been playing with pressure (higher than stock, up to 190mpa, and no I wasnt running huge pulsewidth so it would actually hold >26,000psi) ever since I first got EFILive, and now im at almost 200,000 miles. I had one injector failure in those 200k miles, and it wasnt a cracked body...........


EDIT: The only thing I can think of is maybe since the rail pressure sensor wasnt rescaled in your tune, the ECM didnt know what the actual pressure was, and maybe the actual pressure was REALLY high, like 30,000psi+. Thats a possibility. But I really dont think anything 26-27k area is going to hurt LLY injectors.

 

[juddski88]

I think your last edit hit the nail on the head ben

 

[Rhall]

you guys command full 180mpa?

Yes, and my sensor is not rescaled, so it instantly maxes at 26106 and probably goes to whatever with 2 stroker cp3s

 

[juddski88]

we quickly found through about 20 hours of logging and tuning this weekend that what was being commanded for pressures and what was actual, were very very far off at some times. we got that fixed. but after seeing that, there is no doubt in my mind that for a while now these injectors have been seeing well over 180mpa at times they shouldn't be.

 

[Burn Down]

So was it the crazy tuning you had to do for the LLY swap or is it something that could happen to any of us?

 

[juddski88]

At this point, the only thing different about my truck than any other tuning-wise is that the pw tables dont offer any margin for error, and she likes a couple more degrees of timing than one would think. By a couple, I mean 2-5

 

[juddski88]

But there were times that just because two tables didnt correlate perfectly in idle range, we could watch the truck start at run at 45mpa, as commanded, but then just sitting there would runaway up to 120+ mpa! Lol. Very weird to see.

 

[juddski88]

I shouldve clarified, the only tuning changes that we are making now from a completely different base tune are what you would normally have to make for big injectors, big turbo/no air velocity until spooled, and a cam that comes in at 3000 and hits like a linebacker that youve taunted for 3 quarters

 

[Burn Down]

I shouldve clarified, the only tuning changes that we are making now from a completely different base tune are what you would normally have to make for big injectors, big turbo/no air velocity until spooled, and a cam that comes in at 3000 and hits like a linebacker that youve taunted for 3 quarters

Oh, Know problem then...:rofl: