Proper way to check balance rates

[Blazen]

Sorry it's a 2004 Duramax 6.6 lb7. I'm new to the diesel world how do I figure out the correct fuel rate

 

[THEFERMANATOR]

You have to go through the available pids. Most likely it was only displaying the main injection rate and not including the pilot as total fuel rate is a calculated dynamic pid. So you need to add 1 to your fuel rate as the pilot amount is 1mm3 of fuel at a hot idle. For an lb7 I've seen them in the 7.5-8mm3 of fuel at a hot idle with good injectors. Why are you checking them? Do you have smoke or just testing them? And it's just a diagnostic aide. When I lost 2 injectors in mine, the numbers looked ok, even the corrected numbers were still borderline, but I had 2 that were definately bad causing my blue smokey idle.

 

[Harley2002]

Depends on which fuel rate and what engine. Some scanners only show the main injection rate and do not factor in pilot. Pilot injection is 1mm3 for all stock lb7's, but lly's can be 1-1.5mm3 at idle, and other models I believe can go as high as 3 for pilot. This is why you have to make sure it is total injected fuel rate. And you must havethe engine up to 170 degrees so the modifiers are not adding pilot or adjusting the main for temp. And as I've said before, this is a diagnostic aid to help pin point the problem, not the end all be all test.

 

[Harley2002]

Hi everyone, new to this forum, great site! I'm wondering if the Fermanator or others have heard of or has any opinions on using GM upper engine/injector cleaner? I have a LB7, smokes at idle and has a miss. Using a Predator my rates aren't terrible, without doing the math. My worst is #8 at 4.9? Read in another forum about running this cleaner, pull press. and return, put in a jug of 13 ounces cleaner to 1/2 gal diesel, runs for around 2 hours. Any thoughts?

 

[Sand]

Im running the Torque app for Android. Great display with infinite layouts and warnings (high/low).
But very little info out there for setting up custom PID's. I'd love* love *love* to set up fuel rate or injection rate for my 6.5 DS4 but can't find it. Anyone have more experience with this than me or figured this out?

 

[THEFERMANATOR]

I've used the GM cleaner, it's VERY GOOD stuff. It brought mine back into spec when I lost 2, but it was short lived. Some people have bought an extra year by flushing them, but with an lb7, you're pretty well guaranteed the problem will come back.

 

[Harley2002]

I've used the GM cleaner, it's VERY GOOD stuff. It brought mine back into spec when I lost 2, but it was short lived. Some people have bought an extra year by flushing them, but with an lb7, you're pretty well guaranteed the problem will come back.

Thanks for the reply. I tried it today, rates were all good when I got done and no smoke or miss. Took it for a drive and when I got home it was smoking at a idle and missing again. Guess it's time to bit the bullet and put in new injectors. Have you heard of or tried the TEAM injectors?

 

[THEFERMANATOR]

Thanks for the reply. I tried it today, rates were all good when I got done and no smoke or miss. Took it for a drive and when I got home it was smoking at a idle and missing again. Guess it's time to bit the bullet and put in new injectors. Have you heard of or tried the TEAM injectors?

Never heard of the TEAM injectors. After mine went at 70k miles and several others here recently lost theres with 20k miles, I switched to the 45 over sacs. They take some tuning to make them run right, but overall I'm very happy with them.

 

[Harley2002]

Dang auto-correct, Torque Diesel Manufacturing! ?

 

[THEFERMANATOR]

Couldn't find anything on them. Lincoln diesel has always been a stand up company. If you find lb7 injectors at a cheaper price, my bet is they're junk injectors with new nozzles slapped on, and called reman. Stick to quality parts unless you like doing them multiple times for fun.

 

[Harley2002]

Couldn't find anything on them. Lincoln diesel has always been a stand up company. If you find lb7 injectors at a cheaper price, my bet is they're junk injectors with new nozzles slapped on, and called reman. Stick to quality parts unless you like doing them multiple times for fun.

Torque Diesel Motorsports is the name of them, they are 32%. Another question I have, I noticed when I ran my balance rates every time #2, #4,#6,#8 were all negative numbers (-2.3mm3), any ideas why this would be?

 

[THEFERMANATOR]

Torque Diesel Motorsports is the name of them, they are 32%. Another question I have, I noticed when I ran my balance rates every time #2, #4,#6,#8 were all negative numbers (-2.3mm3), any ideas why this would be?

What are you using to read balance rates? I had this happen on mine when I was running an 01 operating system in the ECM. Others have run into it with the EDGE on early trucks if they're using an OBD2 cable splitter. LB7's can be finicky to read data sometimes, just the nature of the beast, and 01 is the worst as it has some 1 year only data protocols in them.

As to the injectors, I would stick with a KNOWN vendor as to many companies out there talk a good game, but fall WAY short when the chips are on the line. I couldn't find any feedback good or bad on usdiesel parts, so I would be VERY cautious buying from them. Lincoln diesel treated me right as well as everybody I have sent to them, and you will be hard pressed to find another company to go above and beyond like they will for you.

 

[Harley2002]

What are you using to read balance rates? I had this happen on mine when I was running an 01 operating system in the ECM. Others have run into it with the EDGE on early trucks if they're using an OBD2 cable splitter. LB7's can be finicky to read data sometimes, just the nature of the beast, and 01 is the worst as it has some 1 year only data protocols in them.

As to the injectors, I would stick with a KNOWN vendor as to many companies out there talk a good game, but fall WAY short when the chips are on the line. I couldn't find any feedback good or bad on usdiesel parts, so I would be VERY cautious buying from them. Lincoln diesel treated me right as well as everybody I have sent to them, and you will be hard pressed to find another company to go above and beyond like they will for you.

I'm using Diablo Predator for reading the balance rates. I have the truck running on stock though. The rates I came up with were, #1, 2.2/ #2, -1.3/#3, 1.8/#4, -2.9/#5, 2.7/#6, -0.4/#7, 3.9/#8, -4.6. These are not recalibrated. As for the TDM injectors, there is a diesel shop in my town that does a pile of trucks. The owner said for my truck tdm's are the only ones he would run. Claims he has LB7's with over 200,000 on them since he put tdm's in with zero problems. I definitely will be looking at the Lincoln's as well.

 

[THEFERMANATOR]

Theres several out there with stock BOSCH injectors and that many miles as well. Be VERY carefull buying into hype on LB7 injectors. BOSCH still holds the patent on all the parts to the injectors, and the ONLY aftermarket parts for them is nozzles, THAT'S IT! ANY other part of the LB7 injector is under patent from BOSCH, and ONLY BOSCH can make them. And BOSCH ONLY sells to BOSCH certified repair facilities, so for them to even buy the parts, they have to be certified by BOSCH which means they have to have some pretty substantial injector equipment on hand. But it is still BOSCH parts going in them. For oversized injectors there is BOSCH MOTORSPORTS, but it is STILL a division of BOSCH. There's ALOT of hype out there STILL surrounding LB7 injectors.

 

[Eric Musser]

First time posting. Sorry if i'm reviving a old thread. 2006 dmax LLY. At idle with no load in neutral etc my calculated fuel rate varies between 4-8mm3. i guess my first question would be is this an indication of a problem because it's not a steady reading? Second question is when i elevate my fuel pressure with my scanner (it starts out around 30MPA) my calculated fuel rate begins to slowly creep down until when it is around 50MPA my rate is 0 (my balance rates stay pretty much the same just my calculated rate drops). Is this normal or is this an indication of worn fuel injectors? All 8 injectors have around 100k miles on them. I also get thick black smoke under heavy accel and a P0087 when towing my trailer pulling a steep hill. My balance rates are note outrageous they are all somewhere between positive 2 and negative 2, but i'm not sure how much to subtract because my calculated fuel rate isn't steady. Any thoughts or help would be greatly appreciated.

 

[THEFERMANATOR]

First time posting. Sorry if i'm reviving a old thread. 2006 dmax LLY. At idle with no load in neutral etc my calculated fuel rate varies between 4-8mm3. i guess my first question would be is this an indication of a problem because it's not a steady reading? Second question is when i elevate my fuel pressure with my scanner (it starts out around 30MPA) my calculated fuel rate begins to slowly creep down until when it is around 50MPA my rate is 0 (my balance rates stay pretty much the same just my calculated rate drops). Is this normal or is this an indication of worn fuel injectors? All 8 injectors have around 100k miles on them. I also get thick black smoke under heavy accel and a P0087 when towing my trailer pulling a steep hill. My balance rates are note outrageous they are all somewhere between positive 2 and negative 2, but i'm not sure how much to subtract because my calculated fuel rate isn't steady. Any thoughts or help would be greatly appreciated.

That's a dead giveaway for worn ball seats. As rail pressure goes up, more fuel is returned, and this increases fuel output and lowers your calc fuel rate. You can try doing the injector cleaning with GM upper engine/injector cleaner, but I have a feeling if you do an enhanced return rate test, your injectors wouldn't look very good.

 

[Eric Musser]

Thanks for your help and thanks for this thread. Lots of great info!

 

[MetalMaineak]

It drives me nuts to hear people say there balance rates are good, so how can they have bad injectors? Well they might THINK there balance rates are good, but in reality they can be quite the opposite. Balance rates are nothing more than how far off of the average fuel flow each injector is. All DURAMAX engines at idle will adjust the injection amount of fuel to each injector to allow the engine to run as smoothly as possible(until the inejction amount drops down below roughly 2MM3 of fuel, then the ECm freaks out and and goes to all 0's for the balance rates). It uses input from the crankshaft and camshaft position sensors to achieve this cylinder balance, and the amount of fuel plus or minus from the average fuel flow is the balance rate for each cylinder. Balance rate numbers can vary from -7 to +15.

To get the actual balance rate of your cylinders, you must know the fuel rate/injection amount at the time the balance rates are taken(this will become VERY clear in a few minutes why you MUST know this number). The engine should be at 170 degrees or hotter, at a normal 680 idle(01 idle at 600, and LMM's idle at 720), rail pressure should be 35MPA for federal LB7's, and 30 MPA for most others, the battery should be charged with no abnormal loads on the engine(IE A/C off), and vehicle speed is 0MPH(the ECm only does balance rates when the engine is idling, and vehicle speed is less than 2 MPH). The fuel rate/injection amount should be at 8-9MM3 of fuel with all of these conditions met(at sea level it is safe to use the 8MM3 of fuel number, at 5000+ feet use the 9MM3 of fuel number. VVT trucks(LLY+) with the turbo closed at idle like in stock tuning will be closer to 9-almost 10MM3 of fuel at idle due to the extra engine load to spin up the turbo at an idle with the veins closed. And your in gear under these conditions should be roughly 10-13MM3 of fuel. Here is where knowing the fuel rate is so important and why it MUST be figured in.

Let's use a hypothetical example here to determine actual balance rates VS the displayed balance rates. All above conditions are met, and here is the balance rates in neutral(I will skip the in gear as it is the same, just with a different +/- spec).

#1 -2.1
#2 1.4
#3 -0.8
#4 1.2
#5 -1.4
#6 -1.2
#7 2.1
#8 0.8

Well these numbers at first glance look great and well within the GM specs of +/- 4 in nuetral and +/- 6 in gear(ideal would be 0, but no 2 cylinders are idnetical so don't expect to see all 0's. If you you most likely have a serious problem and the ECM has reverted to fail safe and not doing balance rates), but lets correct them to ACTUAL. The fuel rate should be at least 8MM3 of fuel, but the fuel rate is 3MM3 of fuel for this example. So we need to add -5 to all of these balance rates to get the actual numbers(the displayed fuel rate is 5MM3 of fuel low, so it is -5 off). So lets see the corrected numbers.

#1 -7.1 BAD
#2 -3.6 borderline
#3 -5.8 BAD
#4 -3.8 borderline
#5 -6.4 BAD
#6 -6.2 BAD
#7 -2.9 getting up there
#8 -4.2 BAD

These corrected numbers look quite different, and according to these numbers we now have 5 bad injectors, 2 on the edge, and one other that is starting to get up there. This is because like stated earlier balance rates are just an average of how far off each injector is from the average fuel flow which is your fuel rate. And if all the injectors are worn equally(like the above example), then the balance rates will stay close to each other but the fuel rate goes down. Once you learn to figure in the fuel rate to your balance rates, you will get much more accurate results of injector/engine health. But balance rates are just a test and not the end all be all of injector tests as it is just a small portion of what is going on and can be influenced by MANY other variables.

Lets do one more example to show how much balance rates can change once corrected to actual.

#1 -3.0
#2 0.4
#3 -2.8
#4 1.2
#5 -1.4
#6 -1.2
#7 4.5
#8 5.8

Now these numbers at first glance without figuring in the fuel rate show that #7 & #8 are out of the +/- 4 spec, but lets correct them for having a fuel rate of 3MM3. We need to add -5 to them again.

#1 -8.0 BAD
#2 -4.6 BAD
#3 -7.8 BAD
#4 -3.8 borderline
#5 -6.4 BAD
#6 -6.2 BAD
#7 -0.5 GOOD
#8 0.8 GOOD

So now #7 & #8 are the best of the bunch with corrected numbers, and we have 5 others bad with 1 borderline. This illustrates how critical it is to have the fuel rate to correct your balance rates to actual numbers, and why balance rates are worthless without knowing the fuel rate when they were taken.

Another good thing to do if you have the capability is to raise the rail pressure while checking the balance rates. Leaking ball seats will show up better at higher rail pressures than they do in the idle range, so by raising the rail pressure you can get a better idea of ball seat condition without doing a return rate test.

Keep in mind these numbers are for stock engines with stock tunes. If you have a modified tune it must use stock rail pressure at idle, and the fueling needs to be stock from 0-20MM3 of fuel(If in doubt put it back to stock). And if you have oversized inejctors you must have the tables corrected in the 0-20MM3 of fuel areas so that the puslewidths give the correct flow for each cell otherwise the balance rates will be inaccurate.

Also balance rates should not be confused with return rates. Return rates is the amount of fuel each injector returns to the tank during a 15 second cranking cycle, and involves a test set with 4 graduated cylinders to perform as well as some engine teardown to perform it. return rates are a much more accurate test of injector health since 01-10 DURAMAX injectors are a pressure differential valve. They open by opening the bypass port, and when there is a 1400-1500 PSI differential between the incoming fuel pressure and the pressure inside the inejctor it will open. This is why you need at least 1500 PSI for one to start as you have to have the pressure differential for the injector to open. Return rates tell you how well the bypass valves are sealing and if the ball seats are worn or not.

Thank you very much!!!! I've heard so much about these rates but nobody could explain to me how they correspond to each other so I would know what the hell I was looking at! You just brought it all into focus for me, WOW! I was a Steam Power plant engineer for 20+ years. The plant was fully computer automated so I already understand, for the most part, the jargon, how modules interact, and how injectors operate. I definately give credit where it's due. YOU are the MAN!!!

 

[MetalMaineak]

Thank you very much!!!! I've heard so much about these rates but nobody could explain to me how they correspond to each other so I would know what the hell I was looking at! You just brought it all into focus for me, WOW! I was a Steam Power plant engineer for 20+ years. The plant was fully computer automated so I already understand, for the most part, the jargon, how modules interact, and how injectors operate. I definately give credit where it's due. YOU are the MAN!!!

 

[Automotive Needs]

It drives me nuts to hear people say there balance rates are good, so how can they have bad injectors? Well they might THINK there balance rates are good, but in reality they can be quite the opposite. Balance rates are nothing more than how far off of the average fuel flow each injector is. All DURAMAX engines at idle will adjust the injection amount of fuel to each injector to allow the engine to run as smoothly as possible(until the inejction amount drops down below roughly 2MM3 of fuel, then the ECm freaks out and and goes to all 0's for the balance rates). It uses input from the crankshaft and camshaft position sensors to achieve this cylinder balance, and the amount of fuel plus or minus from the average fuel flow is the balance rate for each cylinder. Balance rate numbers can vary from -7 to +15.

To get the actual balance rate of your cylinders, you must know the fuel rate/injection amount at the time the balance rates are taken(this will become VERY clear in a few minutes why you MUST know this number). The engine should be at 170 degrees or hotter, at a normal 680 idle(01 idle at 600, and LMM's idle at 720), rail pressure should be 35MPA for federal LB7's, and 30 MPA for most others, the battery should be charged with no abnormal loads on the engine(IE A/C off), and vehicle speed is 0MPH(the ECm only does balance rates when the engine is idling, and vehicle speed is less than 2 MPH). The fuel rate/injection amount should be at 8-9MM3 of fuel with all of these conditions met(at sea level it is safe to use the 8MM3 of fuel number, at 5000+ feet use the 9MM3 of fuel number. VVT trucks(LLY+) with the turbo closed at idle like in stock tuning will be closer to 9-almost 10MM3 of fuel at idle due to the extra engine load to spin up the turbo at an idle with the veins closed. And your in gear under these conditions should be roughly 10-13MM3 of fuel. Here is where knowing the fuel rate is so important and why it MUST be figured in.

Let's use a hypothetical example here to determine actual balance rates VS the displayed balance rates. All above conditions are met, and here is the balance rates in neutral(I will skip the in gear as it is the same, just with a different +/- spec).

#1 -2.1
#2 1.4
#3 -0.8
#4 1.2
#5 -1.4
#6 -1.2
#7 2.1
#8 0.8

Well these numbers at first glance look great and well within the GM specs of +/- 4 in nuetral and +/- 6 in gear(ideal would be 0, but no 2 cylinders are idnetical so don't expect to see all 0's. If you you most likely have a serious problem and the ECM has reverted to fail safe and not doing balance rates), but lets correct them to ACTUAL. The fuel rate should be at least 8MM3 of fuel, but the fuel rate is 3MM3 of fuel for this example. So we need to add -5 to all of these balance rates to get the actual numbers(the displayed fuel rate is 5MM3 of fuel low, so it is -5 off). So lets see the corrected numbers.

#1 -7.1 BAD
#2 -3.6 borderline
#3 -5.8 BAD
#4 -3.8 borderline
#5 -6.4 BAD
#6 -6.2 BAD
#7 -2.9 getting up there
#8 -4.2 BAD

These corrected numbers look quite different, and according to these numbers we now have 5 bad injectors, 2 on the edge, and one other that is starting to get up there. This is because like stated earlier balance rates are just an average of how far off each injector is from the average fuel flow which is your fuel rate. And if all the injectors are worn equally(like the above example), then the balance rates will stay close to each other but the fuel rate goes down. Once you learn to figure in the fuel rate to your balance rates, you will get much more accurate results of injector/engine health. But balance rates are just a test and not the end all be all of injector tests as it is just a small portion of what is going on and can be influenced by MANY other variables.

Lets do one more example to show how much balance rates can change once corrected to actual.

#1 -3.0
#2 0.4
#3 -2.8
#4 1.2
#5 -1.4
#6 -1.2
#7 4.5
#8 5.8

Now these numbers at first glance without figuring in the fuel rate show that #7 & #8 are out of the +/- 4 spec, but lets correct them for having a fuel rate of 3MM3. We need to add -5 to them again.

#1 -8.0 BAD
#2 -4.6 BAD
#3 -7.8 BAD
#4 -3.8 borderline
#5 -6.4 BAD
#6 -6.2 BAD
#7 -0.5 GOOD
#8 0.8 GOOD

So now #7 & #8 are the best of the bunch with corrected numbers, and we have 5 others bad with 1 borderline. This illustrates how critical it is to have the fuel rate to correct your balance rates to actual numbers, and why balance rates are worthless without knowing the fuel rate when they were taken.

Another good thing to do if you have the capability is to raise the rail pressure while checking the balance rates. Leaking ball seats will show up better at higher rail pressures than they do in the idle range, so by raising the rail pressure you can get a better idea of ball seat condition without doing a return rate test.

Keep in mind these numbers are for stock engines with stock tunes. If you have a modified tune it must use stock rail pressure at idle, and the fueling needs to be stock from 0-20MM3 of fuel(If in doubt put it back to stock). And if you have oversized inejctors you must have the tables corrected in the 0-20MM3 of fuel areas so that the puslewidths give the correct flow for each cell otherwise the balance rates will be inaccurate.

Also balance rates should not be confused with return rates. Return rates is the amount of fuel each injector returns to the tank during a 15 second cranking cycle, and involves a test set with 4 graduated cylinders to perform as well as some engine teardown to perform it. return rates are a much more accurate test of injector health since 01-10 DURAMAX injectors are a pressure differential valve. They open by opening the bypass port, and when there is a 1400-1500 PSI differential between the incoming fuel pressure and the pressure inside the inejctor it will open. This is why you need at least 1500 PSI for one to start as you have to have the pressure differential for the injector to open. Return rates tell you how well the bypass valves are sealing and if the ball seats are worn or not.

Just put two new Bosch injectors in a 2005 Duramax and they both have an actual rate -2.00 to -2.40 give or take what could be the issue?