Fuel Balance Rates

[Border gang]

I have a 2005 and have been having some white smoke only when warm in drive at stop lights. I checked the balance rates and got some really off numbers, I know supposed to be +-4 in park and 6 in drive, but have one side all positive and the other all negative.

1 -7
2 6.5
3-6.9
4 4.3
5 -6.8
6 12.2
7 -3
8 .5

I figure 6 is done and needs replacing, but was going to do the injector cleaning, but not sure how so many can be off, but truck runs good and smooth when not a idle.

 

[WVRigrat05]

I'd use the GM cleaner method to see if it helps but you have several that are borderline. A positive number means it pulling fuel and negative means it's giving extra.

If it were my truck I'd bite the bullet on a new set but try the cleaner first.

It will run good when driving it's burning the fuel, it's at cruise or idle is when they show their effects. Run it too long with bad injectors and you'll crack a piston and or wash cylinder walls and need a motor.

 

[THEFERMANATOR]

I'd use the GM cleaner method to see if it helps but you have several that are borderline. A positive number means it pulling fuel and negative means it's giving extra.

If it were my truck I'd bite the bullet on a new set but try the cleaner first.

It will run good when driving it's burning the fuel, it's at cruise or idle is when they show their effects. Run it too long with bad injectors and you'll crack a piston and or wash cylinder walls and need a motor.

Backwards there. These balance rates are worthless without knowing the fuel rate either. Balance rates are nothing more than how far plus or minus each injector is injecting from the average flow of all 8. Fuel rate at idle should be around 8-9. If the fuel rate is 8, and you have a balance rate of -7, then the ecm is only commanding that injector to inject 1mm3 of fuel or only the pilot shot. A balance rate of 7 would mean the ecm is commanding that injector to inject 15mm3 of fuel per event. Hence why they go from -7 to +15. Anytime the ecm is cutting fuel to an injector the balance rate seems to go to -7 even if say your fuel rate is say 3.

 

[Border gang]

With the GM standard being at idle +-4 these look way out, so as I understand this is from a standard fuel flow rate. Now if I change these I am thinking I should replace them all instead of just a few.

 

[TheBac]

What is your fuel rate??? As Ferm said, you have to know that number in order to really figure it out. You cant assume it is 8. Forget the whole +/- 4 until you find the fuel rate out.

 

[Harbin_22]

What are you checking rates with? Not sure if EFI ever straightened out the LLY rates being the wrong injector location.

 

[WVRigrat05]

My autocal says mine are all 0.5+/-, am I gonna have to figure in fuel rate with it too? I thought I was ass backwards but for some reason I believed that's was right. My brain works so fast I forget things sometimes.

 

[gmduramax]

Isn't it irrelevant what his fuel rate is. One injector is -6.9 and another +12.2. If he fuel rate is 1-100 two injectors are far apart.

 

[Border gang]

I am using an EDGE EFI, so I was not as worried about location as 5 were out of tolerance so I figured I was looking at replacing them all if the injector cleaning did not work. Cold they were all fine, but warm is when everything went bad. I am not sure how to check the fuel rate unless I get another reader as my edge does not have that option.

 

[NC-smokinlmm]

It's main injection rate...

 

[THEFERMANATOR]

If you want to know just how bad the balance rates are, you can't figure that without knowing the fuel rate. Yes he has several injectors way apart, and the ecm is basically shutting fuel off to 3 of them. If his fuel rate is say 3, then all the sudden that 12 hes worried about isnt that bad. If hes doing them all, then go for it, but if he was trying to start with just the bad ones, that high rate one could in fact be a good injector. Also you need to keep in mind cylinder imbalances can drive the balance rates even furthur off. If he has 2 or 3 injectors bad, it can actually cause 1 or 2 to overfuel to try and make up and pull the weight of the cylinders with bad injectors. Hence why balance rates is just one part of checking injectors. But its still best to have accurate data to work with imo.

 

[gmduramax]

If you want to know just how bad the balance rates are, you can't figure that without knowing the fuel rate. Yes he has several injectors way apart, and the ecm is basically shutting fuel off to 3 of them. If his fuel rate is say 3, then all the sudden that 12 hes worried about isnt that bad. If hes doing them all, then go for it, but if he was trying to start with just the bad ones, that high rate one could in fact be a good injector. Also you need to keep in mind cylinder imbalances can drive the balance rates even furthur off. If he has 2 or 3 injectors bad, it can actually cause 1 or 2 to overfuel to try and make up and pull the weight of the cylinders with bad injectors. Hence why balance rates is just one part of checking injectors. But its still best to have accurate data to work with imo.

Makes sense :thumb:

 

[jwilliams198]

So what program or tool (efi live) will show the fuel rate and balance?

 

[Novak]

So what program or tool (efi live) will show the fuel rate and balance?

Tech 2 is what I've heard on here


Sent from my iPhone using Tapatalk

 

[Awenta]

Any decent scanner.

Hell I think the torque app even does it

Sent from my SM-N910V using Tapatalk

 

[WVRigrat05]

My cheap acetron scanner from advance auto reads it.

 

[Border gang]

Ok so found the CFR and when warm at idle sitting at 15-16, not in gear it jumps between 20-27 and is noticeably rougher.

 

[THEFERMANATOR]

Ok so found the CFR and when warm at idle sitting at 15-16, not in gear it jumps between 20-27 and is noticeably rougher.

That changes things DRASTICALLY if thats correct. Shouldn't be any higher than 9 at a warm idle in park. All of the sudden that 12 just turned into an 18 whereas had it been a 3, it would have been a 7. Knowing the fuel rate and balance rate, that means the ecm is commanding 27-28mm3 of fuel on that one injector.

 

[Border gang]

So am I to understand this just confirm the injectors? Sorry but I don't understand the jumping when I put in drive, but his is where it smokes more and runs rougher. Sorry new to Diesel.

 

[THEFERMANATOR]

So am I to understand this just confirm the injectors? Sorry but I don't understand the jumping when I put in drive, but his is where it smokes more and runs rougher. Sorry new to Diesel.

When you put it in drive, the engine gets put under a load, thats why the fuel rate goes up in gear.