04’ Lb7 smokes a lot at idle

[2004LB7]

Reviving an old thread instead of creating a new one.. I have been trying to determine if my injectors are going bad (I am new to diesels (Only had my current truck a little over a year).

I have an 04 silverado 2500 with the lb7. I am getting white smoke at idle.. but even more when in reverse/drive. Reverse is the worst offender in terms of smoke volume.. Drive is hit or miss.. some days its pretty bad (at traffic lights and such) and other days not so bad. In neutral/park its hit or miss.

The smell is pretty distinctly diesel, no fuel in oil and no other symptoms (No power loss, no rough idle, no long cranking to start, etc). I did recently replace the fuel pressure regulator (I forget what its actually called.. replaced it just after Christmas)

I had access to a scanner for about 15 minutes the other day to check for balance rates and such (Are there any decent scanners in the sub $500 category? I got to use a snap on... but I don't have the money to buy one)

Here are a few videos I was able to take to get the data I see people requesting here:

Vid 1:

Source: https://youtu.be/YKNauC7lrqg

Vid 2:

Source: https://youtu.be/n3gSynK2B6M

Vid 3:

Source: https://youtu.be/1gulnw2WW4g

Vid 4:

Source: https://youtu.be/RG7Et7rG82c


While checking for these values the truck was 'cold' and only got to run about 10 minutes, not sure how much that hurts/helps the data.

Balance rates while in park:
0 across all cylinders

Balance rates in reverse but not moving:
cyl 1: 1.9
cyl 2: 1.2
cyl 3: 1.8
cyl 4. 0.5
cyl 5: -3.1
cyl 6 0.5
cyl 7: 1.5
cyl 8: -2.5

CMDS in miliseconds
inj1: 0.38
inj2: 0.29
inj3: 0.28
inj4: 0.29
inj5: 0.35
inj6: 0.40
inj7: 0.32
Inj8: 0.35

fuel rail pressure desired/actual both at 40 MPa

I assume this means I need new injectors since I dont see any values that are way off? Assuming this to be true, are BOSCH still the best factory replacements?

EDIT: forgot to add the truck is at 190k miles, engine is ~170k miles.. it was replaced when the truck was ~20k miles

those numbers won't be reliable until the engine is up to operating temperature. we want the numbers in park and drive/foot on break sitting still while idling. two separate readings. we also need the base mm3 fuel rate to compare to the balance numbers to make any sense of it.

Being an LB7 it is a good bet that the injectors are on there way out. best replacements are SAC style from Lincoln Diesel a vendor on this site.

you could always try doing the GM injector cleaning procedure. if it seems to help then you will know if it is the injectors and you can start planning on replacing them.

 

[GO0BER]

I am absolutely not an expert. There is guys here who are extremely knowledgeable at this and I am not that guy. But doing my research before i bought injectors (and botched my install) I thought the injectors needed to read around 2. Looks like yours are in a wide range, hence the smoke I assume. But I am not an expert. From my experience dont cheap out do the cups too!! Lol.

Ill have to look into doing the cups.. first time I have seen/read anyone recommend doing the cups pre-emptively.. I had read that some struggled with them.. Ill have to look into them.

 

[GO0BER]

those numbers won't be reliable until the engine is up to operating temperature. we want the numbers in park and drive/foot on break sitting still while idling. two separate readings. we also need the base mm3 fuel rate to compare to the balance numbers to make any sense of it.

Being an LB7 it is a good bet that the injectors are on there way out. best replacements are SAC style from Lincoln Diesel a vendor on this site.

you could always try doing the GM injector cleaning procedure. if it seems to help then you will know if it is the injectors and you can start planning on replacing them.

Hmm.. I thought the operating temperature may have been a big factor.. sucks that I didn't have more time with the scanner.

Do you have any recommendations for a decent one in the price range up to $500?

That being said.. when I went back to my posted videos I was able to find several data points that were read in MM3.

Pilot fuel (lowest I saw was 0.9 and highest 1.6)
Fuel rail pressure reg flow (Low 2300 to high of 2540)
Fuel rate (low 1 to high 5)
Main fuel (low 0.9 to high 6.3)

not sure if this helps any in the short term until I can get my hands on a scanner again.

 

[DAVe3283]

If the engine was cold and you only saw a main rate up to 6 mm³, your injectors are toast. They're all leaking substantial quantities of fuel, hence the smoke. When warm, you'd want to see 7+mm³ in Park, and much more in drive. Even more fuel is required when the engine is cold.

For replacements, you can get VCO (stock) or SAC (updated design) injectors. The SAC00 is a good emissions legal option. If you can get a tune, the SAC45 is slightly larger than stock, and often cheaper than the SAC00. Finally Bosch started making brand new stock VCO injectors again. They won't last as long as the SAC style, but are usually cheaper.

Sent from my FlashScan V2 using Tapatalk

 

[THEFERMANATOR]

Since you say your balance rates were all 0, most likely your injectors are done. Balance rates zero out when your fuel rate drops to low and the ecm sees 0 or less fuel being injected into a cylinder. Balance rates are how far +/- each injector is injecting from the main fuel rate. Say you have a balance rate of -2.5, if your fuel rate drops below this number, the ECM 0's them all out. When you put it in gear your balance rates come back because the fuel rate goes up due to it using more fuel.

 

[Bdsankey]

those numbers won't be reliable until the engine is up to operating temperature. we want the numbers in park and drive/foot on break sitting still while idling. two separate readings. we also need the base mm3 fuel rate to compare to the balance numbers to make any sense of it.

Being an LB7 it is a good bet that the injectors are on there way out. best replacements are SAC style from Lincoln Diesel a vendor on this site.

you could always try doing the GM injector cleaning procedure. if it seems to help then you will know if it is the injectors and you can start planning on replacing them.

Unless I'm missing them in the vendor section, LDS isn't a sponsor/vendor on this site anymore.


It sure seems like, from the info that the OP has posted that the injectors aren't healthy and could use replacement. SAC injectors are my go to (usually SAC45 because they've been cheaper than SAC00) and offer some pretty great improvements over the OEM VCO nozzle.

 

[2004LB7]

Unless I'm missing them in the vendor section, LDS isn't a sponsor/vendor on this site anymore.


It sure seems like, from the info that the OP has posted that the injectors aren't healthy and could use replacement. SAC injectors are my go to (usually SAC45 because they've been cheaper than SAC00) and offer some pretty great improvements over the OEM VCO nozzle.

opps, my bad. didn't catch that about LDS

 

[sneaky98gt]

Yup, these guys all already nailed it.

Typically my balance rates get better / more even as the truck warms up, but the main fuel rate goes down / gets worse. Which makes sense, as it takes more fuel for cold idle than warm idle. My injectors have some miles on them (~75k now) with minimal haze, and my cold idle in park is at 9-10 mm3 with warm idle at 6.5-7. In drive bumps it up another few mm3. If you're only at 6 mm3 while cold and in park? Yea, they're very toast.

I don't mean to man-splain this, and there's threads on this forum that go very in-depth on this, so my apologies if you already know this.

The balance rates are simply the amount of fuel, in mm3, that the computer is pulling or adding from each injector to make it idle smoothly. So your #1 cylinder balance rate is 2.9; that means the computer is adding 2.9 mm3 of fuel to that injector. Your #2 cylinder is -2.2, which means the computer is subtracting 2.2 mm3 from that injector. These numbers are relative to the average total fuel being used (a.k.a. main fuel rate).

In a perfect world, it should take around 8 mm3 main fuel rate to idle a warmed truck in park (more if cold, and more in drive, obviously). If your measured rate (with the scanner) is less than this (say 5 mm3), then that 5 mm3 is what the computer thinks is the total consumption. But since we know that it actually takes around 8, then we can assume that the 3 mm3 difference is leaking past the worn injectors.

When you combine these two numbers, you can get a pretty good idea of the health of the injectors. The problems begin when the total injected amount gets too low (which means that the remainder is leaking past during the rest of the combustion cycle). Using my numbers above, cylinder 1 is +2.9 on the balance rate, and -3.0 on the main fuel rate, for a total deviation of -0.1 (or an actual number of 7.9). Cylinder 2 is -2.2 on the balance rate, and still -3.0 on the main rate, for a total deviation of -5.2 (actual of 2.8). And so on.

The general rule of thumb is that you'll start to get hazing when the total deviations reach -6.0 or further (2.0 or less actual). This can happen when the main rate stays pretty high but a balance rate or two is way off (which is what happened to me, and was caused by a single injector failing). Or it can happen with pretty good balance rates, but the main rate is way low (which is what you've got, which means all of the injectors have failed fairly evenly over time).

This is why you can't diagnose injectors with balance rates alone. Your balance rates are actually not terrible, but the main fuel rate being so low indicates that they are toast.

 

[GO0BER]

If the engine was cold and you only saw a main rate up to 6 mm³, your injectors are toast. They're all leaking substantial quantities of fuel, hence the smoke. When warm, you'd want to see 7+mm³ in Park, and much more in drive. Even more fuel is required when the engine is cold.

For replacements, you can get VCO (stock) or SAC (updated design) injectors. The SAC00 is a good emissions legal option. If you can get a tune, the SAC45 is slightly larger than stock, and often cheaper than the SAC00. Finally Bosch started making brand new stock VCO injectors again. They won't last as long as the SAC style, but are usually cheaper.

Sent from my FlashScan V2 using Tapatalk

That makes sense.. Is there any online resource that has some kind of graph/chart of what values one should expect to see or is this just knowledge you have built along the way of ownership? I couldn't find anything.. though to be honest. because I am so new to diesels and am quite ignorant.. I may just not be googling the correct terms.

That being said.. I am also very illiterate in terms of injectors and their designs. I do in fact have an 'old' EDGE tuner (4 blue buttons on the silver faceplate), not sure that would qualify for the SAC45?

Ultimately I want an injector that is as close to stock (or what will work best with the EDGE tuner I have) that is expected to have the longest life span. The injectors in my truck are original (pushing ~170k miles on them) and I would love to see a similar life span if possible. I don't use my edge tuner for HP.. in fact I use it for extra MPG when not towing and then I return it to stock when towing. I was expecting the injectors alone to be ~$2k is that correct or have prices jumped quite a bit in the last year?

 

[GO0BER]

Since you say your balance rates were all 0, most likely your injectors are done. Balance rates zero out when your fuel rate drops to low and the ecm sees 0 or less fuel being injected into a cylinder. Balance rates are how far +/- each injector is injecting from the main fuel rate. Say you have a balance rate of -2.5, if your fuel rate drops below this number, the ECM 0's them all out. When you put it in gear your balance rates come back because the fuel rate goes up due to it using more fuel.

That makes sense.. It was definitely all 0's in park.. once in gear the popped up. I am learning all kinds of new things about the LB7 fuel system today

Thanks!

 

[GO0BER]

Unless I'm missing them in the vendor section, LDS isn't a sponsor/vendor on this site anymore.


It sure seems like, from the info that the OP has posted that the injectors aren't healthy and could use replacement. SAC injectors are my go to (usually SAC45 because they've been cheaper than SAC00) and offer some pretty great improvements over the OEM VCO nozzle.

Do you happen to have a link to the brand/type you prefer? The only thing I had found on my initial searches is that BOSCH are the 'go to/best' for factory replacements..

Thanks so much!

 

[Bdsankey]

Do you happen to have a link to the brand/type you prefer? The only thing I had found on my initial searches is that BOSCH are the 'go to/best' for factory replacements..

Thanks so much!

I’m a vendor here, I’ll shoot you a message.


Sent from my iPhone using Tapatalk

 

[GO0BER]

Yup, these guys all already nailed it.

Typically my balance rates get better / more even as the truck warms up, but the main fuel rate goes down / gets worse. Which makes sense, as it takes more fuel for cold idle than warm idle. My injectors have some miles on them (~75k now) with minimal haze, and my cold idle in park is at 9-10 mm3 with warm idle at 6.5-7. In drive bumps it up another few mm3. If you're only at 6 mm3 while cold and in park? Yea, they're very toast.

I don't mean to man-splain this, and there's threads on this forum that go very in-depth on this, so my apologies if you already know this.

The balance rates are simply the amount of fuel, in mm3, that the computer is pulling or adding from each injector to make it idle smoothly. So your #1 cylinder balance rate is 2.9; that means the computer is adding 2.9 mm3 of fuel to that injector. Your #2 cylinder is -2.2, which means the computer is subtracting 2.2 mm3 from that injector. These numbers are relative to the average total fuel being used (a.k.a. main fuel rate).

In a perfect world, it should take around 8 mm3 main fuel rate to idle a warmed truck in park (more if cold, and more in drive, obviously). If your measured rate (with the scanner) is less than this (say 5 mm3), then that 5 mm3 is what the computer thinks is the total consumption. But since we know that it actually takes around 8, then we can assume that the 3 mm3 difference is leaking past the worn injectors.

When you combine these two numbers, you can get a pretty good idea of the health of the injectors. The problems begin when the total injected amount gets too low (which means that the remainder is leaking past during the rest of the combustion cycle). Using my numbers above, cylinder 1 is +2.9 on the balance rate, and -3.0 on the main fuel rate, for a total deviation of -0.1 (or an actual number of 7.9). Cylinder 2 is -2.2 on the balance rate, and still -3.0 on the main rate, for a total deviation of -5.2 (actual of 2.8). And so on.

The general rule of thumb is that you'll start to get hazing when the total deviations reach -6.0 or further (2.0 or less actual). This can happen when the main rate stays pretty high but a balance rate or two is way off (which is what happened to me, and was caused by a single injector failing). Or it can happen with pretty good balance rates, but the main rate is way low (which is what you've got, which means all of the injectors have failed fairly evenly over time).

This is why you can't diagnose injectors with balance rates alone. Your balance rates are actually not terrible, but the main fuel rate being so low indicates that they are toast.

No worries on the 'man splaining'.. I am both a guy and one who is eager to learn.. I have no problem admitting when I don't know anything on a given topic (and here I am with the LB7 fuel system... very ignorant lol )

I will continue to poke around on here for other info I am wanting to learn, but you all have been more than helpful already.

Cheers!

 

[DAVe3283]

That makes sense.. Is there any online resource that has some kind of graph/chart of what values one should expect to see or is this just knowledge you have built along the way of ownership? I couldn't find anything.. though to be honest. because I am so new to diesels and am quite ignorant.. I may just not be googling the correct terms.

That being said.. I am also very illiterate in terms of injectors and their designs. I do in fact have an 'old' EDGE tuner (4 blue buttons on the silver faceplate), not sure that would qualify for the SAC45?

Ultimately I want an injector that is as close to stock (or what will work best with the EDGE tuner I have) that is expected to have the longest life span. The injectors in my truck are original (pushing ~170k miles on them) and I would love to see a similar life span if possible. I don't use my edge tuner for HP.. in fact I use it for extra MPG when not towing and then I return it to stock when towing. I was expecting the injectors alone to be ~$2k is that correct or have prices jumped quite a bit in the last year?

If you're going to stick with a canned tuner, then you'll need either stock or the SAC00 injectors. SAC45 requires a proper EFILive tune. Since you're not looking for any extra power, it sounds like the SAC00 might actually be your best bet. You'll pay a bit more for the injectors but then you don't need a tune which will save money.

As for the expected fuel rates, it's just what we've picked up from a bunch of people sharing what their trucks do, so we have a baseline expectation. There is a GM spec for the maximum allowable balance rate for any individual injector in Park and in Drive. IIRC it's ±2mm³ in Park, ±4mm³ in Drive. The decreasing main rate is something the diesel community noticed, I don't think any GM documents mention that.

Sent from my FlashScan V2 using Tapatalk

 

[2004LB7]

If you're going to stick with a canned tuner, then you'll need either stock or the SAC00 injectors. SAC45 requires a proper EFILive tune. Since you're not looking for any extra power, it sounds like the SAC00 might actually be your best bet. You'll pay a bit more for the injectors but then you don't need a tune which will save money.

As for the expected fuel rates, it's just what we've picked up from a bunch of people sharing what their trucks do, so we have a baseline expectation. There is a GM spec for the maximum allowable balance rate for any individual injector in Park and in Drive. IIRC it's ±2mm³ in Park, ±4mm³ in Drive. The decreasing main rate is something the diesel community noticed, I don't think any GM documents mention that.

Sent from my FlashScan V2 using Tapatalk

little correction. 4 in park and 6 in drive

 

[GO0BER]

If you're going to stick with a canned tuner, then you'll need either stock or the SAC00 injectors. SAC45 requires a proper EFILive tune. Since you're not looking for any extra power, it sounds like the SAC00 might actually be your best bet. You'll pay a bit more for the injectors but then you don't need a tune which will save money.

As for the expected fuel rates, it's just what we've picked up from a bunch of people sharing what their trucks do, so we have a baseline expectation. There is a GM spec for the maximum allowable balance rate for any individual injector in Park and in Drive. IIRC it's ±2mm³ in Park, ±4mm³ in Drive. The decreasing main rate is something the diesel community noticed, I don't think any GM documents mention that.

Sent from my FlashScan V2 using Tapatalk

Awesome.. This is helping me narrow down to the actual injectors I need to order. I'll have to spend some time searching for a thread/how to on replacing them to make sure I don't need any specialty tools. From what I have seen it looks like you just need to remove some of the hoses and stuff up top (similar to the 5.3 liter knock sensors) and then take off the valve covers.. but having never actually done it.. I am sure there will be some tool that is required and/or super handy that just makes life easier.

Is there a brand that is best? In my research leading up to me finding this forum I kept seeing BOSCH everywhere.. but tons of people warning of "fake" BOSCH as well.. Or is there a reputable site to order from? @Bdsankey had mentioned sending me a message with some info.. Haven't seen one come yet (to be fair.. it hasn't been that long)


Thank you for sharing your knowledge base.. I have far less anxiety now about spending $2k or so on injectors than I did yesterday. Much appreciated

 

[darkness]

You’re going to want to replace all 8 injectors! If you’re doing the job yourself you’ll quickly find out why. And I would recommend getting new high pressure lines as well. Other than rust and corrosion they will be full of debris at the nuts that you just can’t clean out with brake cleaner.

 

[Bdsankey]

Awesome.. This is helping me narrow down to the actual injectors I need to order. I'll have to spend some time searching for a thread/how to on replacing them to make sure I don't need any specialty tools. From what I have seen it looks like you just need to remove some of the hoses and stuff up top (similar to the 5.3 liter knock sensors) and then take off the valve covers.. but having never actually done it.. I am sure there will be some tool that is required and/or super handy that just makes life easier.

Is there a brand that is best? In my research leading up to me finding this forum I kept seeing BOSCH everywhere.. but tons of people warning of "fake" BOSCH as well.. Or is there a reputable site to order from? @Bdsankey had mentioned sending me a message with some info.. Haven't seen one come yet (to be fair.. it hasn't been that long)


Thank you for sharing your knowledge base.. I have far less anxiety now about spending $2k or so on injectors than I did yesterday. Much appreciated

I just sent you a message. I was laying in bed and fell asleep before hitting "create message" haha.

 

[GO0BER]

You’re going to want to replace all 8 injectors! If you’re doing the job yourself you’ll quickly find out why. And I would recommend getting new high pressure lines as well. Other than rust and corrosion they will be full of debris at the nuts that you just can’t clean out with brake cleaner.

Oh for sure.. I a not replacing anything less than all 8. I learned in an older car that even when you have "good" injectors that are old.. if they aren't all matched correctly you can run into issues.. so there is that lol

I also planned on new high pressure lines as well

 

[GO0BER]

I just sent you a message. I was laying in bed and fell asleep before hitting "create message" haha.

No worries! It was pretty late at night for me too.. And it happens to the best of us