Diesel Place banner
1 - 14 of 14 Posts

wayne12345678

· Registered
Joined
·
12 Posts
Discussion starter · #1 · (Edited)
This is a new truck to me 43k, I just got a Edge Evolution CTS mostly for towing, MPG, and code reading/diagnostics. First time I read the injector rates the truck was at operating temp, which I guess is not very accurate. Is that true? Any ways # 7 injector was @ 6 in Drive. So i read up a bit, waited over night, and read them this morning. One main question is how cold is a valid cold temperature? For the first minute or so #7 was around 2.5-3.1 then after a minute it did jump up.... So the last reading I wrote down, operating temp was 111 degrees RPM 660 in Park.

Park * Drive
-1.7 * -0.9
0.8 * 1.5
-1.1 * -1.9
-2.1 * -2.0
0.1 * -1.4
2.0 * 2.1
3.6 * 4.3
-1.0 * -1.7
 
they should be checked while warm. do you have any smoke at idle or makin any oil? what are the concerns you had for checking them? what are the ballance rates in park?
 
I have a CTS and I also found it odd that the CTS screen says to read the rates with the engine cold. I have rates (2) out of spec when cold, when it warms up, it is totally good. I really don't give a damn what it is doing cold.
Maybe a call to edge and see why they say check cold??
Wags

Oh, I have some power issues. It is a CP3. (maxes at about 11K) I found this with the CTS. I love it.
 
John C,
Does the smoke at idle indicate the injectors are due for replacement? I have 123k miles on the original injectors.
 
smoke at idle is the most common symptom. sometimes they fill up the crank case with diesel. if you have absolutely no issues of injectors i would drive it for now. i just wanted to know what caused you to look at the injectors in the first place. or were you just cuious to know what they were without having any issues?
 
I had read some other threads about smoking at idle and the mention of replacing injectors. My truck does smoke at idle although not heavily and not always noticible. I just started adding Lucas injector cleaner at fill up. Haven't noticed a difference yet. The truck runs great other than the smoking at idle.
 
injector cleaner wont help if your truck is smoking at idle. duramax's run about 22,000 PSI fuel pressure. they usually blow everything through them rather than getting dirty. if your truck is smoking you need injectors. i recomend doing all 8 at once. or at least do the 4 on the side of number 7 (i believe that is the passenger side.) theres a tiny ball inside the injectors similar to a ball bearing. you could imaging what happens to a ball bearing with fuel flowing through it at 22,000 psi all the time.once that ball erodes it lets fuel into the cylinder, causing un-burnt fuel. (your smoking).
 
Smoking

Jon C.

Do not want to hi-jack the thread, but if you can not replace all eight, why replace the 4 on the passenger side? Does this side go out sooner?

Thanks Dee
 
no but the one bad one he has is on the passenger side. so while he is in that side, replace those 4 because there is a lot of work to get these things apart, just to save yourself work in the future more than anything. i would definately recomend doing all 8 though while your doing them. once one goes... the rest will soon follow. not to mention then you have 8 new ones and know they are all new.
 
The diesel tech locally told me the reason you check when they are cold is because your readings will be at their worst when the engine is cold. As the truck warms, these rates become less sever and sometimes will mask the bad rates.

Thats what I was told. I just got through replacing 3 of mine, one of which was a positive 10. Upon inspection of that injector, the nozzle tip was corroded from excessive heat and brown. You will need to AT LEAST replace that injector reading 6 .. until you do, you will have decreased power, rail pressure issues, and most likely a knock or rougher idle.
 
Balance rates should not be checked while the truck is cold. The "warm up" features like intake air heater would be putting more of a load on the engine causing more fuel to be sprayed and thus give an erroneus reading. Things like that should not be factored in when doing a balance rate check, which is why you check with the engine at normal operating temps with as many accessory loads turned off as you can.
 
The diesel tech locally told me the reason you check when they are cold is because your readings will be at their worst when the engine is cold. As the truck warms, these rates become less sever and sometimes will mask the bad rates.

Thats what I was told. I just got through replacing 3 of mine, one of which was a positive 10. Upon inspection of that injector, the nozzle tip was corroded from excessive heat and brown. You will need to AT LEAST replace that injector reading 6 .. until you do, you will have decreased power, rail pressure issues, and most likely a knock or rougher idle.
Your mechanic is wrong.

The injector balance rate will be worse when the truck is warm, not when it is cold.
Always check the rates when it is warm, because the injectors tend to perform worse when warm vs. cold.

He has that mixed up.
 
GM's specs are when the engine temp is at least 180 deg F.

+/- 6 when in drive
+/- 4 when in neutral
 
Your mechanic is wrong.

The injector balance rate will be worse when the truck is warm, not when it is cold.
Always check the rates when it is warm, because the injectors tend to perform worse when warm vs. cold.

He has that mixed up.
well im not callin anyone out here or anything, wasnt my intention .. but ive noticed every single time when i check my balance rates in the morning when the truck is cold (35 degrees out), balance rates are ALWAYS worse (positive readings). if we are talking positive readings, it would make sense that the balance rates would be worse when cold.

I could also see negative readings being worse when warm because the fuel/injectors has warmed up and become less viscous leading to a greater potential for leakage..
 
1 - 14 of 14 Posts