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I don't think I am missing anything. The truck doesn't run just "OK", it runs great! My point is running the numbers the way described in this thread told me that I have 7 bad injectors and 1 good one. That is exactly backwards to reality. The one it says is good is the bad one(well not bad bad but worse than the others). and the other 7 are fine. They are not new so I know they are not perfect.

I'm not going to argue about this one anymore. I said what I had to say. People can take it as is or ignore it. It doesn't really matter to me. I just hate to see people spending a ton of money to replace a part that may not be bad. A return test is the only way to test for sure.

But you also think a sooty piston top is worse than a clean piston top...... Would you think a white spark plug is better than a nice golden brown?
 
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But you also think a sooty piston top is worse than a clean piston top...... Would you think a white spark plug is better than a nice golden brown?

No, I said:

While I had the heads off and was cleaning the block I noticed the #1 cylinder had much more soot build up than the rest (a significant amount more).
So you're telling me a dirty cylinder is a good running cylinder? There is nothing that sounds right about that.
and I still hold true to what I said. Extra diesel in a cylinder will produce soot (ie black smoke). The soot will build up on the piston. I never said anything about a piston being washed by a completly bad injector.

But you can take it how ever you want. Doesn't really matter to me.
 

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Discussion Starter #43 (Edited)
For what it's worth, this is a BAD sign.


And this is a GOOD sign.


The bad injector was only a -2.7 balance rate, but you can clearly see it was washing the piston down from a poor spray pattern.
 

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THEFERMANATOR, Thanks for a great write up on something to help with diagnosing a problem without the labor intensive test for return rate. I think most people reading this picked up on the comments you made about how this was not the definitive way to determine whether to buy injectors or not, and was only a way to help check out why balance rates can appear to be acceptable while not really being so. I want to also thank iwantdiesel for calling you out on this. That difference in opinion made this post even more informative. Thanks all.
 

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Do you or anyone else know if you can get the main fuel rate that you are speaking of using the OBD2 Bluetooth connector with the Torque app for Android? I know it gives balance rates. I'm just looking for an inexpensive way to check these rates with and without your adjustments to the balance rates but I don't want to spend too much. I'm not planning on doing any tuning. I'm just troubleshooting a starting problem. Buying a tuner is outside my budget right now considering injector replacement may be in my near future.
 

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I've got a bit of a predicament.

I'm assuming you use the fuel rate when in neutral and then the fuel rate shown when in gear correct?

This is what I'm getting for numbers.

In neutral, fuel rate is 6
1= -.97 corrected to -2.97
2= 2.39 corrected to .39
3= -.77 corrected to -2.77
4= .13 corrected to -1.87
5= 1.06 corrected to -.94
6= 3.64 corrected to 1.64
7= -2.67 corrected to -4.67
8= -2.63 corrected to -4.63

Uncorrected, 2, 7, and 8 are starting to get up there 6 is right there. Corrected 1 and 3 are up with 7 and 8 now out.

This is the loop, this is in gear, fuel rate is now at 10
1= -.66 to 1.34
2= 2.23 to 4.23
3= -.44 to 1.56
4= -.34 to 1.66
5= .27 to 1.73
6= 3.81 to 5.81
7= -2.09 to .09
8= -2.66 to .66

Now uncorrected shows the same, but corrected 2 and 6 are out. But now 7 and 8 are damn near 0.

Main reason I am asking is I was all set to change the driver side bank (that bank only due to time and money) based off of a previous log were that showed most withing spec with 6 close and 8 out of spec. That was done using the method shown in the thread but only in idle, I did not at that time look at the fuel rate in gear which looking back did the same thing as this time.
 

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Discussion Starter #47
I've got a bit of a predicament.

I'm assuming you use the fuel rate when in neutral and then the fuel rate shown when in gear correct?

This is what I'm getting for numbers.

In neutral, fuel rate is 6
1= -.97 corrected to -2.97
2= 2.39 corrected to .39
3= -.77 corrected to -2.77
4= .13 corrected to -1.87
5= 1.06 corrected to -.94
6= 3.64 corrected to 1.64
7= -2.67 corrected to -4.67
8= -2.63 corrected to -4.63

Uncorrected, 2, 7, and 8 are starting to get up there 6 is right there. Corrected 1 and 3 are up with 7 and 8 now out.

This is the loop, this is in gear, fuel rate is now at 10
1= -.66 to 1.34 -2.66
2= 2.23 to 4.23 .23
3= -.44 to 1.56 -2.44
4= -.34 to 1.66 -2.34
5= .27 to 1.73 -1.73
6= 3.81 to 5.81 1.81
7= -2.09 to .09 -4.09
8= -2.66 to .66 -4.66

Now uncorrected shows the same, but corrected 2 and 6 are out. But now 7 and 8 are damn near 0. You subtracted your -2. You want 8mm3 of fuel in nuatral, but close to 12mm3 of fuel in gear. So you need to add the -2 to the numbers like you did in the 1st set of numbers.

Main reason I am asking is I was all set to change the driver side bank (that bank only due to time and money) based off of a previous log were that showed most withing spec with 6 close and 8 out of spec. That was done using the method shown in the thread but only in idle, I did not at that time look at the fuel rate in gear which looking back did the same thing as this time.
Remember your adding -2 since your fuel rate is lower than ideal. You got it right for in nuetral, but in gear you subtracted.
 

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Remember your adding -2 since your fuel rate is lower than ideal. You got it right for in nuetral, but in gear you subtracted.
Ok, I missed in the original post that it should be 12mm3 in gear. Only saw the 8 so was subtracting the 2 to compensate for the thinking it was high by 2mm3.
 

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Did I do my calculations correct?

Idea Actual Difference
8- 5.3 =2.7


Cylinder
1= 2.5 = -0.2
2= 0.6 = -2.1
3= 1.1 = -1.6
4= 0 = -2.7
5= -0.9 = -3.6
6= 2.8 = 0.1
7= -7 = -9.7
8= 1.5 = -1.2


Then I did it again and got similar numbers:

Ideal Actual Difference
8- 5.9 =2.1

Cylinder
1= 1.8 = -0.3
2= 0.8 = -1.3
3= 1.3 = -0.8
4= 0.1 = -2
5= -1.1 = -3.2
6= 2.8 = 0.7
7= -7 = -9.1
8= 1.7 = -0.4


I have excessive white smoke at idle and when running that smells of raw diesel.

Thanks
 

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That number 7 appears to be leaking, eh?
 

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Discussion Starter #51
Did I do my calculations correct?

Idea Actual Difference
8- 5.3 =2.7


Cylinder
1= 2.5 = -0.2
2= 0.6 = -2.1
3= 1.1 = -1.6
4= 0 = -2.7
5= -0.9 = -3.6
6= 2.8 = 0.1
7= -7 = -9.7
8= 1.5 = -1.2


Then I did it again and got similar numbers:

Ideal Actual Difference
8- 5.9 =2.1

Cylinder
1= 1.8 = -0.3
2= 0.8 = -1.3
3= 1.3 = -0.8
4= 0.1 = -2
5= -1.1 = -3.2
6= 2.8 = 0.7
7= -7 = -9.1
8= 1.7 = -0.4


I have excessive white smoke at idle and when running that smells of raw diesel.

Thanks
#7 is maxed out on the balance rate, -7 is as low as it can go. I would say it is hung open or not fully closing as the ECM is commanding it to barely fuel(probably only firing it for the pilot shot, and not any for the main). From looking at your numbers, I would guess you have somedebris that got in your fuel rail as #5 is also getting up there, and 5 & 7 are right next to each other at the rear of the passenger side of the engine.
 

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Thanks, so what would you recommend? Cleaning the injectors first with the GM procedure or injector replacement at #5 & #7. Trying to see how money I'm fixin' to spend.
 

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I finally got my Edge Insight installed and read my balance rates. Here are my as read and corrected balance rates if I understood the correction factor as my fuel rate should be 8mm3 and I read 6mm3 so I would add -2 to the as read value.
In neutral
#1 as read -1.8 corrected -3.8
#2 2.3 .3
#3 -0.5 -2.5
#4 1.1 -1.1
#5 1.8 -.2
#6 2.8 0.8
#7 -4.5 -6.5
#8 -1.1 -3.1

In gear
#1 as read -0.9 corrected -2.9
#2 2.7 .7
#3 -0.4 -2.4
#4 0.1 -2.1
#5 0.9 -2.9
#6 3.2 1.2
#7 -4.8 -6.8
#8 -0.8 -2.8
Am I doing the correction factor right?
And, from these reading #7 is bad and the rest look OK, am I correct?
I'd really appreciate some guidance
Thanks!
Jim
 

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Where did you find actual fuel on a snap on scanner? New Verus scanner. All I've found is corrected rate.

Been a tech for over 30 years but now sorta being forced into diesel drivability issues..... Yay me :clap:


edit: never mind, found it
 

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Have an 05 LLY here with calculated rate of 14 and main of 12.

so far I have for balance #'s

2)4 1)-2
4)-1 3)0
6)-2 5)-1
8)3 7)-1

Yes it has some white smoke, towed in

Now here's the fun part.... I no longer have 1 dmax to play with now I have 2... other is an 06 LBZ and on my Snap On Verus scanner there's no main or actual fuel rate, just calculated. This one has a knock around 1200rpm but goes away (for the most part) above that rpm
 

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Great article explaining the true way to get a decent view of the fuel system condition from the balance rates.

Now for some opinions on my new to me LB7, truck is an 04 with 270k, was told it had recent (which in my opinion could be any number of miles) injectors, balance rates are fairly even except for a few but fuel delivery rate is pretty low from what I read, numbers taken in the pic were after a 50 mile highway drive, had been idling a few minutes and coolant had dropped down to the 150's already, outside temp was about 12*F, approx elevation is 1900' here. Truck has a very very faint hazy after idling a few minutes, not sure if it's fuel haze or cold weather haze. What has me slightly concerned is that it sounds like it has a fuel knock at cruising on the highway (approx 2300 rpm) from the passenger side, this is my first dmax so I'm not used to the normal running sounds.

I've tried the oil on a paper towel test but it looks normal, oil level is still full, have about 4k on the oil and oil life monitor show 53% remaining, going to drop it this week anyways and get an analysis done on it to see what fuel levels are like in it, to me it seems to be too clean for a diesel, but like I said this is my first dmax so I'm learning the normals for it.

Thanks for looking at my long post!!
 

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Be nice to see the GM service procedure for checking the balance rates using a Tech II. Can our injectors be bench tested, seems like that would be a lot easier than doing a return rate test.......just a thought.
 

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Bubbacummings was that data in gear or out of gear?
 

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This is what I'm getting for balance rates on my truck using EFI Live. The truck has 124,000 miles on stock injectors and has a fuel knock above idle but none of the other injector symptoms like fuel in oil, or exhaust haze. I am almost certain that it is the injectors but I just want to be certain before I pull the trigger on a bunch of parts.



Any thoughts?

WRxc
 
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