Checking Balance Rates

Rattlin_Ram

Rattlin_Ram

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Aug 8, 2007
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Ok I know jack about Dmax's so help a cummins guy out here...

I have a buddy with an '05 LLY, which he believes is bone stock cept exhaust. He bought it used. He claims it is idling kinda rough, and feels like it stumbles at highway speeds. No codes are being thrown. He is worried it is an injector. I think the truck has about 100k on it.

So after some research I found you can check balance rates to check injectors with EFI live.

I have another buddy with EFI live and says for $100 I can buy a license and use it to scan the other guys truck.

Is this correct?

What steps do I have to go through to do this with EFI live? I work in IT for a living so know my way around computers so comfortable with that, just never worked with EFI live or a Dmax.

I read about the ice pick trick, but I think that usually throws a code as to which injector is malfunctioning. Also read about the wire harness over the alternator, but that usually also throws a code.

Anything else it could be?
 
Rattlin_Ram said:
Ok I know jack about Dmax's so help a cummins guy out here...

I have a buddy with an '05 LLY, which he believes is bone stock cept exhaust. He bought it used. He claims it is idling kinda rough, and feels like it stumbles at highway speeds. No codes are being thrown. He is worried it is an injector. I think the truck has about 100k on it.

So after some research I found you can check balance rates to check injectors with EFI live.

I have another buddy with EFI live and says for $100 I can buy a license and use it to scan the other guys truck.

Is this correct?

What steps do I have to go through to do this with EFI live? I work in IT for a living so know my way around computers so comfortable with that, just never worked with EFI live or a Dmax.

I read about the ice pick trick, but I think that usually throws a code as to which injector is malfunctioning. Also read about the wire harness over the alternator, but that usually also throws a code.

Anything else it could be?
Click to expand...

I'm not 100% sure but I don't think you have to buy a VIN license to do a balance test, only to load a tune into a truck.

Is he getting any white smoke? Cold or otherwise?
 
You only need a license to flash the ECM. logging doesn't require one. You do need the software downloaded onto your laptop to use it though; it's free from EFILive's site.
It may not be related at all but tell him to make sure his fuel filter is fresh. A dirty one causes some strange drivability problems.
 
JD4440 said:
You only need a license to flash the ECM. logging doesn't require one. You do need the software downloaded onto your laptop to use it though; it's free from EFILive's site.
It may not be related at all but tell him to make sure his fuel filter is fresh. A dirty one causes some strange drivability problems.
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I agree^^ dirty fuel filter will do strange things with the duramax. If you decide to check the injectors with EFI you will have to click on PID's in the scan tool program. Then double click 1-8 balance rates and then click on data. It will show the current, high, and low B/R's, I believe + or - 4 while the truck is in drive (idling) is with in GM spec...
 
custom8726 said:
I agree^^ dirty fuel filter will do strange things with the duramax. If you decide to check the injectors with EFI you will have to click on PID's in the scan tool program. Then double click 1-8 balance rates and then click on data. It will show the current, high, and low B/R's, I believe + or - 4 while the truck is in drive (idling) is with in GM spec...
Click to expand...

X2 on this and make sure your are at operating temp (don't check when the truck is cold)
 
Well successfully got EFI live installed on my laptop, and scanned the truck. Balance rates looked ok. They where all within +-4 while in D idling.

There where several codes that came up on it though, including a misfire from #6. I cleared the codes to see if any would come back. What came back right away was an HVAC code, and a TCM code. Looked up the TCM code and I think that came up because we had just changed the fluid in the trans. And it was about a quart shy of being full, had to run to town yet to get another quart.

But after driving it both wheel speed sensors up front threw codes. Could wheel speed sensors cause a defuel or anything that would cause a shudder right at 60mph?
 
+ or - 4 is a little high. It is gm spec, but i think they set the spec high to avoid some warranty claims.
 
They where less than 3 actually if I remember right...

What are the "best" numbers to go by?
 
I'm wondering if the speed sensor codes are being caused by worn out unit bearings. They would definitely cause a shudder I would think. Maybe jack the front end ub and shake the tire to check for bearing wear ??
 
Rattlin_Ram said:
Well successfully got EFI live installed on my laptop, and scanned the truck. Balance rates looked ok. They where all within +-4 while in D idling.

There where several codes that came up on it though, including a misfire from #6. I cleared the codes to see if any would come back. What came back right away was an HVAC code, and a TCM code. Looked up the TCM code and I think that came up because we had just changed the fluid in the trans. And it was about a quart shy of being full, had to run to town yet to get another quart.

But after driving it both wheel speed sensors up front threw codes. Could wheel speed sensors cause a defuel or anything that would cause a shudder right at 60mph?
Click to expand...


I do not believe so^^ MY speed sensor codes and a few others are always on when I check it. Theres no check engine lights or anything like that, but If I scan for DTC's they will appear. I clear them but it does not change anything. You did change the fuel filter correct??
 
JD4440 said:
I'm wondering if the speed sensor codes are being caused by worn out unit bearings. They would definitely cause a shudder I would think. Maybe jack the front end ub and shake the tire to check for bearing wear ??
Click to expand...

Never heard of the bearings causing speed sensor codes?? I know in Salted road areas such as ny the sensors stop working because of corosion. I believe the OP means a engine shutter? If not then yeah possibly wheel bearing, ball joints, tie rods, pitman/idler arm, etc,etc...
 
custom8726 said:
Never heard of the bearings causing speed sensor codes?? I know in Salted road areas such as ny the sensors stop working because of corosion. I believe the OP means a engine shutter? If not then yeah possibly wheel bearing, ball joints, tie rods, pitman/idler arm, etc,etc...
Click to expand...

I was just throwing that out there as something he might check for the shudder, was purely a guess on my part.
 
Fuel filter was the first thing he changed.

I have yet to be in the truck when it happens, it's intermittent. But it always happens at road speed, about 60mph. Says it feels like the truck is defueling or maybe something in the transmission. Says it goes away when you let off the fuel, or if you hammer on it.
 
Well the truck did it while his wife was driving it to work yesterday, so brought it down and we scanned it again. The only new code was a misfire on #6.

So he is gonna try the "Icepick" fix on #6.

While he was there I checked his balance rates again, and #4 was really high.... like +8 or so.
 
Rattlin_Ram said:
Well the truck did it while his wife was driving it to work yesterday, so brought it down and we scanned it again. The only new code was a misfire on #6.

So he is gonna try the "Icepick" fix on #6.

While he was there I checked his balance rates again, and #4 was really high.... like +8 or so.
Click to expand...

Well thats not good (+8) I missed the part about it being an LLY, definetly check the harnesses as this is a very common isssue with them^.. I would get a bottle of power service and dump the whole thing in (100g mix) Run it for a little while and check the B.R. rates again in drive, at idle, while the motor is warm. The good thing is if its an injector the LLY's are easy to change out. The problem is just because the B.R.'s are off on that one particular cylinder does not mean that injector is the bad one or the only bad one. The computer will try and compensate for faulty injectors to balance them out. I dont know if that came out clear or not? I ended up pulling my injectors out about 5 different times untill I got all the B.R. back in check.
 
custom8726 said:
Well thats not good (+8) I missed the part about it being an LLY, definetly check the harnesses as this is a very common isssue with them^.. I would get a bottle of power service and dump the whole thing in (100g mix) Run it for a little while and check the B.R. rates again in drive, at idle, while the motor is warm. The good thing is if its an injector the LLY's are easy to change out. The problem is just because the B.R.'s are off on that one particular cylinder does not mean that injector is the bad one or the only bad one. The computer will try and compensate for faulty injectors to balance them out. I dont know if that came out clear or not? I ended up pulling my injectors out about 5 different times untill I got all the B.R. back in check.
Click to expand...

I was not aware that one injector can affect others! But that is probably the reason I was told if you replace one, just replace them all...

IF we replace injectors should we upgrade to a 50 or 70hp injector? This is a stock truck, but to spend that much cash on stock injectors seems ridiculous to me! Is there a place that can rebuild stock injectors for a reasonable amount?
 
I am not sure about the LLY injectors being rebuilt. I would assume they are rebuildable since the LB7 ones are. You could contact pensacola to find out for sure, I know they rebuild LB7 injectors and are about 1/3rd the cost of most others. With the duramax's its just the tips (nozzles) that get honed out for bigger injectors. The factory injectors and nozzles in the LLY are good for better then 600RWHP so going bigger is not really necessary in a DD unless you are going all out. That said, I would not buy all new injectors for an LLY because of one bad B/R.. When you say you heard to replace all of them, I would have to assume you heard that from LB7 owners, being that they are notorious for faulty injectors. They are also a real PITA since they are under the valve covers and require about 3 times the amount of time to change out VS the newer gens 04 1/2 - present. Its fairly rare to get a bad injector in an LLY. I would replace the one with the Highest B/R and see were you end up. There not cheap and more then likely all but 1 or 2 are still good and will remain good for the forseable future. But............... Check the wiring harnesses and run some diesel kleen through it first, then move onto the $$ items..
 
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