Long time lurker... but I barely post.

Recently purchased an LLY block to put in my 2004 (which is actually an LB7 '04). Confirmed by the head tech @ PPE the LB7 and LLY blocks are identical. The difference are elsewhere int he motor/harness etc. Nonetheless I have spent my free time over the last few days transferring everything from my motor over to this short block which is supposed to have around 22k on it.

Got everything on and installed the motor. Took about a minute of priming and starting and it finally started but at first would barely stay running without holding the key, but eventually would but ran EXTREMELY rough. Basically no throttle response for about 5-10 sec and then would slowly move up to around 1800 rpm before it would halt.

At first it threw code P0336 - which is for CKP performance. Upon reading I went ahead and changed my fuel filter since I was putting a new motor in with new oil and such and actually believe the filter could have need to be changed. Immediately after changing it primed MUCH faster and got ALOT harder to push which when the previous one was still installed it was always mushy and never really got firm firm.

I picked up a cheap scanner to read the codes and went ahead and cleared them after installing the new filter. Now it still runs very rough but seems to start and idle easier but still idles very bad, it just doesn't require you to keep holding the pedal and the key until it stays running. However, now the code will not reappear no matter how many times I start the truck and let it run, but it does show it as a pending code, just not a permanent one.

The coolant is very low as I found a leak after everything was installed where apparently a gasket is bad or something so it is not holding much at the moment and the tranny fluid is also low. I do not believe these to effect the performance of the motor in park but I figured it was worth mentioning.

Also, before it is mentioned, I always get diesel from the same station by my house and I am very confident there is not a problem with the fuel and no need to drain the tank or anything.

If anyone has any ideas as to what it could be I would appreciate it.

your code is for crank shaft position sensor. Located on the front cover adjacent to the crank snout. Two possible problems, one it's not connected, or two you have swapped the crank shaft sensor wire with the cam shaft sensor wire. If I recall correctly, they both use the same pin config and the wires are long enough to reach either plug.

or there is some other problem with the sensor.....

I don't think your the first guy to do it, a bad crank shaft signal will cause the problems you are having.

Check it out and let us know.

your code is for crank shaft position sensor. Located on the front cover adjacent to the crank snout. Two possible problems, one it's not connected, or two you have swapped the crank shaft sensor wire with the cam shaft sensor wire. If I recall correctly, they both use the same pin config and the wires are long enough to reach either plug.

or there is some other problem with the sensor.....

I don't think your the first guy to do it, a bad crank shaft signal will cause the problems you are having.

Check it out and let us know.

I think you hit the nail on the head, those symptoms are typical of a bad/disconnected Crank pos sensor. check that sensor and let us know....

Those were the first things I checked. On my harness the Crankshaft sensor is signifantly shorter and because of the grounds that are bolted on the bottom of the block it is physically impossible to plug it into the cam sensor.

I unplugged it and the motor would only turn over for 5-6 seconds and stop. Would not even try to fire. So I would assume the sensor is functioning. It was also functioning fine before the new block (I used the one out of my old motor (lb7 block) because it it was brass and the one in my motor (lly block) was just cheap plastic)

http://www.youtube.com/watch?v=1TwTuxF0toQ

Did a LBZ low end swap in my 01. One of the problems I had was with the main loom connections. They were not tight & it ran tough. I just happened on to this problem. When checking on other thoughts for the rough running. There is a TSB on the loom connections also. When mating, the loomes will at times break at the stake points in the loom. This allows for poor to no contact. Pull the looms apart & very carefully with a needle nose pliers check to see if they are in place or have come loose & slid back. Also as I recall there was something to do with the crank position sensor but cuz of "Old Fart Ites" I can't remember what it was. But something has to be done to it when switching form the LB7 to LBZ block. Maybe this will jog someone elses gray matter. Good luck. I also had to reflash the ECM but that was on a 01

what exactly are you calling a loom connection and what exactly do you mean by stake points. I think I know what your talking about but never hear it referred to as that, but will definitely check it out. I did find 3 wires that be rubbed to the wire and through some of the wire on the driverside down by where the intercooler pipe makes the final bend before entering the coupler. I taped them up so that could short or ground out but it doesn't appear to have made a difference.

I also did an LLY block. My understanding was they were the same. I know there is a few differences between the LB7/LLY and LBZ, but I don't think they apply to the LB7 - LLY.

what exactly are you calling a loom connection and what exactly do you mean by stake points. I think I know what your talking about but never hear it referred to as that, but will definitely check it out. I did find 3 wires that be rubbed to the wire and through some of the wire on the driverside down by where the intercooler pipe makes the final bend before entering the coupler. I taped them up so that could short or ground out but it doesn't appear to have made a difference.

I also did an LLY block. My understanding was they were the same. I know there is a few differences between the LB7/LLY and LBZ, but I don't think they apply to the LB7 - LLY.

On the LB7 there are two main wire loom connections on drivers side top of engine. The stake points are where the male & female connections are made. the plastic housing holding either the male or female fitting will crack & allow the m/f ends to move back when mated not making contact or making poor contact.

I gotcha. Yea i just talked to Nick @ Merchant Automotive and he as well thinks it is most likely a grounded wire or a bad 5v ground. I will be removing the harness inspecting and reinstalling carefully and see what happens.

Didnt' completely remove harness but what I did do did not seem to change anything. I am curious if anyone knows if the ground positions on the block make that much of a difference.

I was going to swap the LLY Crank Sensor and realized the pins were bigger. So I cleaned the old one back up by cleaning out the inside of the plug and the sensor and put it back on. Oddly enough it still runs bad but runs better. It will rev upwards of 2500 now and seems to get there much quicker...

Gonna pick up a new one tomorrow and see what happens. Any more info would still be useful though. I'm still playing the guessing game.

Welp no luck today. I could really use some ideas....

Today:
-Replaced crankshaft position sensor
-Meticulously went over harness. No other splices other than what has already be fixed.
-Took off all grounds on block and sanded the block down to bare metal, cleaned the wire fitting and reinstalled.

STILL throwing code P0336. And still running very rough although runs better (still bad) with MAF unplugged it seems. Also seems to accelerate the the rpms fast at partial throttle rather than full throttle. Still have not attempted to drive it yet.

Any more thoughts? I could really use a few more opinions.

Which sensors are LLY & which are LB7. I keep going to back the crank sensor we changed the one on my 01 LB7 3 times each was different. Also at this point I would give Tim a call at St Joe Diesel 816) 233-3736. He does a number of these conversions & is pretty sharp. They built my engine. It would be worth a couple of bucks to talk to the guy. One other thought, have you cleared all the codes, cycled the ignition key 6 times & restarted your truck.
Good Luck & keep us posted on your progress.

The lly and LB7 don't have different reluctors do they? I don't think so but....

The reluctor wheel wasn't bent or anything was it? Did you have it torn down to bare block and rebuild or did it have the front cover on already? Is running stock programming?

Just trying to throw out ideas.....between the code and the rough running it seems like it must be the CPS. But maybe something else it wrong and it is throwing the CPS off. Hard to tell if it's a symptom or cause.

What do you mean each one was different. Everything I have found shows one Crank Position Sensor. I know the LLY one is different though.

To answer the question ALL sensors are LB7 except the one on the back of the block on the driver side. I don't know if thats oil pressure or what but that is LLY.

So this St. Joe Diesel is going to charge me just to talk to him? I just need to figure it out.

I talked to the guys at Merchant and the reluctor wheels are supposed to be the same. And no it is not bent. I had to replace the front cover because it has a crack in it. The block was not rebuilt. It was a perfectly fine running block with 22k on it so I did not rebuild it.

SOME MORE INFO FROM THE WEEKEND:

-Had a friend bring over his Matco SCAN tool and got some balance rates.

With the MAF still unplugged (forgot to plug it in) I got these numbers at idle.

1 - 15.00
2 - 15.00
3 - 15.00
4 - 7.00
5 - 7.00
6 - 7.00
7 - 15.00
8 - 15.00

Once I plugged the MAF back in it would bounce routinely from 0.00 to somewhere between 7-10 to somewhere between 13-15. I don't remember the exact numbers. Then it would go back to 0 and keep going in that cycle. If I increased throttle it would go straight to 0.00 as though it wasn't reading I would assume.

I found all of this very odd. The previous motor overheated extremely bad and blew the head gaskets and bent a push rod. However I do not see how that could have caused all the injector to be off by this much. The way the numbers are coming off it seems like the ECM or FICM is bad but again I don't understand how either of those would go bad just from the motor problems..

I have access to the scan tool whenever I need. Is there anything else I should check.

You got those numbers exactly? all .00? That seems weird. I would say that your injectors are probably OK. Those numbers are being caused by the rough idle. Balance rate just measures how much the injection amount has to change to make it idle smooth. Obviously these are maxed out or somehow artificially influenced by the idle problem. Balance rates are only read at idle.

How does overheating cause a bent pushrod? Just wondering if something else is wrong.

When you reassembled the short block you didn't lash the valves 180 degrees out of phase did you? It has been done before. basically just a WAG (wild ass guess).

My gut says electrical problem but.....internet diagnostics don't have a great track record.

Time to drag it to a shop and pay to get it running.

I second the possibility of valve adjustment being off.

Yes the first numbers were exactly to .00. Once the maf was plugged in they were no longer .00 but they jumped around as mentioned.

Yes I completely understand what the balance rates tell you. And I figured out after posting, balance rates on read at idle so that explains the latter part.

The bent pushrod I imagine came from water in the cylinder... Piston @ TDC Valve comes down but cant due to the water and boom push rod bends.

As mentioned the block was not rebuilt. I replaced it with what was supposedly a running motor with 22,000 miles on it.

I actually thought about it being the valves, just have been trying to rule out everything else before pulling the valve covers again. I really am leaning away from electrical unless its the ECM/FICM itself, which I don't understand how that can just go bad from the motor conditions, would just seem very odd. I have meticulously checked over the harness. I have removed all grounds and cleaned the connectors and sanded the block down to clean metal.

Taking it too a shop is most likely a waste of time and money. I am a competent mechanic and although spending most of life on gas motors have learned quite alot over the last couple of year of owning this Duramax. I have access to the same diagnostic equipment as a diesel shop. I am not going to pay someone to test the same things I can test myself. At this point whatelse can they do? Pull the injectors and test each one. They will charge 3k to pull them. While a local diesel shop charges $50/injector if you pull them. They can swap ecm's maybe but may require the purchase of parts and crap. Getting work done around here is a joke. The dealers will play the same guessing game just at my expense. I have read to many stories on here of people having problems and when the first thing doesn't fix it they basically just keep guessing while the owner is shelling out green backs with no return.

At this point the only things I see left are:
-Bad ECM (unlikely)
-Bad FICM (unlikely)
-Bad connection at injectors in head (again unlikely)
-Valve out of adjustment severely (quite possible)
-Bad injectors, but would look to be all of them (and if so, unlikely)
-Worst case, bad block of which isn't holding compression. (possible)

Guess will be pulling the valve covers this week when I have some free time.

What do you mean each one was different. Everything I have found shows one Crank Position Sensor. I know the LLY one is different though.

To answer the question ALL sensors are LB7 except the one on the back of the block on the driver side. I don't know if thats oil pressure or what but that is LLY.

So this St. Joe Diesel is going to charge me just to talk to him? I just need to figure it out.

I talked to the guys at Merchant and the reluctor wheels are supposed to be the same. And no it is not bent. I had to replace the front cover because it has a crack in it. The block was not rebuilt. It was a perfectly fine running block with 22k on it so I did not rebuild it.

SOME MORE INFO FROM THE WEEKEND:

-Had a friend bring over his Matco SCAN tool and got some balance rates.

With the MAF still unplugged (forgot to plug it in) I got these numbers at idle.

1 - 15.00
2 - 15.00
3 - 15.00
4 - 7.00
5 - 7.00
6 - 7.00
7 - 15.00
8 - 15.00

Once I plugged the MAF back in it would bounce routinely from 0.00 to somewhere between 7-10 to somewhere between 13-15. I don't remember the exact numbers. Then it would go back to 0 and keep going in that cycle. If I increased throttle it would go straight to 0.00 as though it wasn't reading I would assume.

I found all of this very odd. The previous motor overheated extremely bad and blew the head gaskets and bent a push rod. However I do not see how that could have caused all the injector to be off by this much. The way the numbers are coming off it seems like the ECM or FICM is bad but again I don't understand how either of those would go bad just from the motor problems..

I have access to the scan tool whenever I need. Is there anything else I should check.


I doubt Tim @ St Joe Diesel would ever charge for info. As for the cam sensors I know two were changed. The other item that may have been changed was the reluctor wheel as I remember the cam sensor helped but did not give 100% cure. Tim may remember as there were may items tried. I can remember being as frustrated as you are & all that were working on the engine were the same.

Good luck & try Tim @ St Joe Diesel he is a good guy.

Will give him a call today. Thank you

Hey I hear ya when it comes to paying others to work on your truck. That's why I do it all myself now. I also remember being extremely frustrated when it took me longer to chase wiring problems on my truck then it did to COMPLETELY rebuild an engine AND tranny. Took me 6 months from the time it died to get it fully back on the road. Lots of nights and weekends.

If your willing to put in the time and struggle through it you have my respect. I didn't mean to suggest that you weren't able, just trying to save you some frustration.

Valve lash is next, along the same lines are the crank and cam drive gears located correctly? Dots lined up? Cam pin intact? All those problems would have the same symptoms.

Compression check is next,(maybe first) that will prove out the block, head gasket, rods and valves to a certain extent. At least it should show MAJOR issues that would cause your truck to run that rough.

Here is the book diag for a p0336 just in case you didn't have it

DTC P0336

DTC DESCRIPTORS

DTC P0335
Crankshaft Position (CKP) Sensor Circuit

DTC P0336
Crankshaft Position (CKP) Sensor Performance

DIAGNOSTIC FAULT INFORMATION

IMPORTANT: Always perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. See: Diagnostic Trouble Code Tests and Associated Procedures

TYPICAL SCAN TOOL DATA

CKP Sensor Signal Present






CIRCUIT/SYSTEM DESCRIPTION
The hall effect crankshaft position (CKP) sensor signal indicates the crankshaft speed and position. There are 57 teeth on the front of the crankshaft sprocket, plus a sync gap. The CKP sensor will output an ON/OFF pulse as each window passes the sensing element. The CKP sensor is connected directly to the engine control module (ECM) by the following circuits:


The 5-volt reference circuit
The low reference circuit
The signal circuit
CONDITIONS FOR RUNNING THE DTC

P0335


The engine is cranking or running.
The camshaft position (CMP) sensor signal is present.
DTC P0335 runs continuously when the above conditions are met.
P0336


The engine is cranking or running.
DTC P0336 runs continuously when the above condition is met.
CONDITIONS FOR SETTING THE DTC

P0335
The ECM determines no signal from the CKP sensor for less than 8 seconds .

P0336
The ECM determines that the CKP sensor signal is out of range for less than 2 seconds .

ACTION TAKEN WHEN THE DTC SETS


The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/Failure Records.
CONDITIONS FOR CLEARING THE MIL/DTC


The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
Clear the MIL and the DTC with a scan tool.
DIAGNOSTIC AIDS


An intermittent CKP sensor signal may cause DTC P0336 to set. Wiggle the wiring harness with the engine running and observe the CKP Sensor Pulses Missed parameter on the scan tool. If the parameter indicates anything other than 0, there is an intermittent condition.
Inspect for insufficient fuel.
CIRCUIT/SYSTEM VERIFICATION


If DTCs P0642 or P0643 are set, diagnose those DTCs first.
The engine starts and runs.
CIRCUIT/SYSTEM TESTING


With the key ON and the CKP sensor disconnected, measure the voltage between the 5-volt reference and a good ground and observe that the DMM measures 4.98-5.02 volts .
If the DMM does not measure 4.98-5.02 volts , test the 5-volt reference for an open, high resistance, or a faulty ECM.
With the key ON and the CKP sensor disconnected, measure the voltage between the 5-volt reference circuit and the low reference circuit, and observe that the DMM measures 4.98-5.02 volts .
If the DMM does not measure 4.98-5.02 volts , test the low reference for an open, high resistance, or a faulty ECM.
With the key ON and the CKP sensor disconnected, connect a fused jumper wire to the signal circuit and momentarily and repeatedly probe the low reference circuit, and observe that the Crank Signal Present and engine RPM parameters change.
If the crank signal parameter and engine RPM does not change, test the signal circuit for an open, high resistance, a short to ground, a short to voltage, or a faulty ECM.
Ensure that the CKP sensor circuits are not routed too closely to the fuel injector wiring, after-market add-on electrical equipment, solenoids, relays, or motors.
Inspect the CKP sensor for physical damage, loose or improper installation, excessive air gap, or foreign material passing between the sensor and the reluctor wheel.
Inspect the CKP reluctor wheel for physical damage, improper installation, or excessive endplay or looseness.
If no other condition is found, replace the CKP sensor.
REPAIR INSTRUCTIONS

IMPORTANT: Always perform the Diagnostic Repair Verification after completing the diagnostic procedure.


Crankshaft Position (CKP) Sensor Replacement
Control Module References for ECM replacement, setup, and programming
Crankshaft Reluctor and Oil Pump Drive Gear Replacement
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