2009 LMM won't rev over 2k rpms.

[04chase]

have you tried running a parked manual regen to see if it will rev above 2k? iirc they rev to 2500 rpm during a service static regen.
.

can you read commanded fuel pressure vs actual ?
ive heard of cp3's doing this but it sounds like yours is being electronically limited.

 

[JayPrimo]

Well, no matter what happens.....please stick around. You'll find this is a great group of Dmax people. Good luck.

Thanks, I plan on it. I'll be working on these things for at least another 10 years, and aside from the debacle this truck turned into, I actually have some decent knowledge and experience I can share myself lol

 

[JayPrimo]

have you tried running a parked manual regen to see if it will rev above 2k? iirc they rev to 2500 rpm during a service static regen.
.

can you read commanded fuel pressure vs actual ?
ive heard of cp3's doing this but it sounds like yours is being electronically limited.

I haven't tried to burn it, but I doubt it would be different. This ****er does it even in park and neutral. Plus it's very "frowned upon" doing standing regens on 2009's in my shop, after 2 of them went up in flames in previous years lol

And yes, I can command fuel pressure well above the "13kpsi threshold" that happens on it's own. Desired reads +20kpsi, actual reads +20kpsi, idles like a bag of shit, then I rev it with these fuel numbers and it still bounces at 2k rpm.

 

[JayPrimo]

Of course boss wanted to see under the front cover. I felt it was a waste of time considering what the scope showed us, but whatever, I get paid by the hour. Bosses orders.

Surprise, nothing bad under there. Timing on point, crank pins have no damage.......siggghhhhh.....this is very frustrating.

Cover is back on with the water pump in. Of course our parrs department doesnt have a pump, supposedly will get it tomorrow. We'll see what happens, keep ya'll posted

 

[JoshH]

It doesn't sound exactly the same, but somewhat similar. I had a customer with an LBZ bring in a truck that around the same RPM (don't remember exactly because it was a few years ago), would immediately cut fuel like a hard rev limiter and bounce off that RPM. It also would throw a crank position sensor code. We finally concluded it was a broken crank and found it broke right in the middle at the #3 main. I hope that isn't your problem, but it's something to consider if the fuel path doesn't produce a fix.

 

[JayPrimo]

It doesn't sound exactly the same, but somewhat similar. I had a customer with an LBZ bring in a truck that around the same RPM (don't remember exactly because it was a few years ago), would immediately cut fuel like a hard rev limiter and bounce off that RPM. It also would throw a crank position sensor code. We finally concluded it was a broken crank and found it broke right in the middle at the #3 main. I hope that isn't your problem, but it's something to consider if the fuel path doesn't produce a fix.

Oh wow. Whenever we have snapped cranks, theyre no starts. The one you had wss idling and revving to the "limiter" no problem though? That's crazy, amd absolutley worth thinking about :thumb:

 

[JoshH]

Oh wow. Whenever we have snapped cranks, theyre no starts. The one you had wss idling and revving to the "limiter" no problem though? That's crazy, amd absolutley worth thinking about :thumb:

Yep, I think because it broke so far back is why it acted like it did.

 

[JayPrimo]

Yep, I think because it broke so far back is why it acted like it did.

Insane. We were entertaining the idea of the crank being twisted since it ran and idled fine. Forget curveballs, you just threw a knuckleball out there for us to think about.

Still waiting for the pump, suppose to get it tomorrow. If the pump doesnt do it, oil pans are comig down

 

[Chevy1925]

Insane. We were entertaining the idea of the crank being twisted since it ran and idled fine. Forget curveballs, you just threw a knuckleball out there for us to think about.



Still waiting for the pump, suppose to get it tomorrow. If the pump doesnt do it, oil pans are comig down

Just remember, trans has to come out to get the upper pan off

 

[JayPrimo]

Just remember, trans has to come out to get the upper pan off

Oh sure. I've done my share of upper pans and rear covers in this place. Stupid design

 

[Bdsankey]

Oh sure. I've done my share of upper pans and rear covers in this place. Stupid design

Could always pull lower pan and take a look with an inspection camera.

 

[JayPrimo]

Could always pull lower pan and take a look with an inspection camera.

For sure, definitely going to give that a shot before diving into the upper pan.

Still waiting on the pump. Boss has me workin on other trucks in the meantime. Will be keeping everyone updated as I make more progress

 

[JayPrimo]

Hey guys. Checking in with an update. Finished the pump last week and no bueno, same shit. "Rev limiter" still kicking in, Primer still stays soft which i find odd. The only check valve labelled in that return line is the one built into the pump. Unless here's a check valve in the junction block, then I'm baffled why my primer stays soft.

Regardless, i'm now at a total loss and tell the boss I want to do a full teardown, that I suspect the motor is fubar somewhere. He's not buying it's a mechanical issue, is convinced it's an electrical problem kicking in a limiter.

Problem is now since I did the pump, the problem is WORSE. Happens closer to 1800 rpm now, and sound much more like a fuel knock or a stumble as opposed to a limiter. I find it hard to believe a limiter imposed by the ecm would be so varied.

Today I feel we made major progress though. We started scoping injectors, got through injectors 2 and 3, and saw no change in the injector pulse while it was bouncing. Bingo on it not being an electrically controlled limiter if you ask me. So then my other boss asks if did a running compression test, which we did not. We get ourselves all set up, my boy has his scope with a pressure switch mounted up to the scope. Compression waveform looks wierd, so we decide to do a standard test with a regular gauge and the glow plug adapter.

Lo and behold, this engine ramps up to near 700 psi in cylinder one, then blows the schrader valve right theough the damn adapter. We've done plenty of running compression tests, and never saw this kind of pressure, let alone blow out the schrader valve.

What do you guys think about our compression numpers and what happened during the test? Any ideas on if this pressure isn't normal, which I'm pretty certain it isn't, why is is ramped up so high? When I do a static test, no cylinder went over 450 psi. But then again, EVERY cylinder ramped up to 450psi exactly the same.....which i found strange. No variation between cylinders at all? What's the likelihood of that? I'd say slim to none, no?

 

[2004LB7]

Maybe a leaking injector causing some combustion?

 

[clrussell]

I’ve seen lmm limp for two things.

Rail pressure, and mass airflow.

What kind of air filter and what’s the grand per sec at idle

 

[rmk800ak]

Did you try running it out of a 5 gallon bucket ? At least that would rule out anything in the lines or fuel pickup. It still is confusing why the plunger is not solid. Should be super simple to do.


Sent from my iPhone using Tapatalk

 

[Chevy1925]

I don’t think I’ve ever felt a plunger be solid after running it. You still get a 1/2 to full pump when you try again.

So is this 450psi on all 8 cyl, engine cold and cranking/not running?

I’d pull glow plugs (all of them), tank the belt, throw a breaker bar on the balancer, have someone hold the converter from moving and see if you can work it back and forth. If you get any clunking, I’d think that would solidify the situation on if the crank is bad.

Don’t remember if you did this but have you pulled the front cover to make sure the cam pin has not broke and spun?

 

[NC-smokinlmm]

Seized or carbon in rings will cause excessive compression.

 

[JayPrimo]

Well, we got it :woott:

Combination of 3 slightly bent teeth on the crank reluctor and a warped CKP housing causing a phantom sync gap to appear at high rpms, thus causing the injector to attempt to fire twice on the same stroke. Once the computer would see the injector grounding out for its second fire, it would shut them down and go to stall, but since the sensors, signals, and reluctors were essentially ok, it would re synce and fire again, thus causing a "rev limit"

When we first scoped out the crank, and watched it during the "limiter", we saw it wasn't losing signal and not losing it sync pulse, so we ruled it out.

Once I started scoping the injectors I was watching them against the cam pulse and not really seeing much other than injectors firing. So my boss comes over and says to put it against the crank signal. What I wasn't seeing was was the injector not misfiring, but attempting to fire again within the same pulse. We zoom in on the info, and lo and behold, at high rpms the crank signal is developing a "phantom" sync and attempting to fire the injector twice on the same stroke. Paying more attention now, we see some teeth on the crank signal look a littler funny. So I pull the CKP and housing again, and put a straightedge on the opening. Sure as shit 3 teeth are bent ever so slightly off center towards the rear of the engine that missed during my inspections. Probably not a big deal, I'm assuming they had been bent since it was reman'd and it ran fine so far, and the ckp picked up signal and idled fine right? So now I bolt the ckp to the housing in my hands, and damn me if it isn't warped ever so slightly causing the sensor to lift when you tightened up the bolt. Never would see it if it was on the truck when installed. And wouldn't you know, the edge of the sensor face that is lifted, is the back edge where the 3 teeth would "stray" from. So at low rpms, it picked up the signal fine. A little fuzzy around the damaged teeth, but nothing alarming. Once you got the engine revving though, maybe crankcase pressure was lifting the sensor even more and all of sudden, ecm is seeing a second injector pulse gap in the same rotation, attempting to fire again, then realizing it's mistake and trying to stall, but then it would simply fire again normally until the phantom gap appeared again. It wasn't consistently appearing ever revolution either.

Bent the teeth back to center line, and put a shim under the sensor so it stayed straight when bolted down. Fired up the truck, and she took me straight to redline :nanawrench:

I thank you guys for all your help and input. I had every intention of posting pics of the scope images, but in my frustration/excitement/releif, I saved the wrong file and blew it. Sorry. Any questions I'll be happy to discuss.

Oh, and btw. The damn primer still doesn't firm up when pumping lol.

 

[darkness]

Damn that’s a hell of a find...good job!