Fuel injector balance test, results significantly different on each bank

[kocheric]

I have a question for the tech guys in the group.

 

Have a 2017 suburban, with the big 5.3, 66,*** miles.

 

I am experiencing some runablity issues that I am trying to diagnose. 

 

Symptoms include:

 

-A rough idle when warm and in gear.  It always starts good, and is smooth when warming up.

 

-A hesitation when pulling away from a stop.  The truck responds well initally, but then sort of falls off a bit.  This is also noticeable when at speed on the freeway, if you give it just a touch of pedal, it feels like it loses a bit of power, but then comes back when lifting off the gas a bit.

 

-When approaching a hill while cruising, if one gives a bit of throttle to compensate, it will begin to dog out a bit and can regularly feel like it is misfiring.

 

I have had 1 instance of a flashing check engine light when giving a bit of throttle to compensate for a hill when it was not completely warmed up.

 

The plugs were replaced as a health and inspection check, but they all like normal.  I have not noted anything unusual with scan data that I can discern.  Fuel trims are correct and no check engine light. 

 

I ran an injection balance test, and found some interesting information.  All of bank 1 pressure drops were significantly different from bank 2.  I did this yest at warm idle, then did another test at around 850 rpm, which yielded similar results.

 

A little research led me to tsb notice N182198000, could this be 4 failing injectors, all on the same bank?

 

I am not a parts cannon guy, and I'm not sure if this is covered under my used car warranty.  I worry about dealer services, because I'm not sure they always take the time to accurately diagnose  before throwing parts around.  Thanks for any help, and sorry for the long post.  Trying to be as accurate and descriptive as  can.  I will try to attach the results of the injector balance test as well.

Edited March 12, 2024 by kocheric

[BlancoSilverado]

Hmm, i've done mine in the past and the left and right banks were different like yours but the banks were within 5% of each other. Not sure what is going on with yours. Possibly your injectors 2 and 7 are going out? 

[newdude]

20 hours ago, kocheric said:

I have a question for the tech guys in the group.

 

Have a 2017 suburban, with the big 5.3, 66,*** miles.

 

I am experiencing some runablity issues that I am trying to diagnose. 

 

Symptoms include:

 

-A rough idle when warm and in gear.  It always starts good, and is smooth when warming up.

 

-A hesitation when pulling away from a stop.  The truck responds well initally, but then sort of falls off a bit.  This is also noticeable when at speed on the freeway, if you give it just a touch of pedal, it feels like it loses a bit of power, but then comes back when lifting off the gas a bit.

 

-When approaching a hill while cruising, if one gives a bit of throttle to compensate, it will begin to dog out a bit and can regularly feel like it is misfiring.

 

I have had 1 instance of a flashing check engine light when giving a bit of throttle to compensate for a hill when it was not completely warmed up.

 

The plugs were replaced as a health and inspection check, but they all like normal.  I have not noted anything unusual with scan data that I can discern.  Fuel trims are correct and no check engine light. 

 

I ran an injection balance test, and found some interesting information.  All of bank 1 pressure drops were significantly different from bank 2.  I did this yest at warm idle, then did another test at around 850 rpm, which yielded similar results.

 

A little research led me to tsb notice N182198000, could this be 4 failing injectors, all on the same bank?

 

I am not a parts cannon guy, and I'm not sure if this is covered under my used car warranty.  I worry about dealer services, because I'm not sure they always take the time to accurately diagnose  before throwing parts around.  Thanks for any help, and sorry for the long post.  Trying to be as accurate and descriptive as  can.  I will try to attach the results of the injector balance test as well.

 

 

Looks like you've got a lot of leaking injectors.  Some much worse than others.  

 

Ideally it should have a dealer run an AFIT test on it (Active Fuel Injector Tester) as it will show the balance rates properly per GM specs.

 

N182198000 is not a bulletin, its a special coverage that is VIN specific.  You'd have to run your VIN and see if it has that coverage.  

 

If you want to bypass dealer diagnosis and seeing if its got special coverage, 8 new injectors, the two high pressure fuel pipes and 8 intake gaskets and grab some tools.  

 

 

Edited March 13, 2024 by newdude

[TEEREV77]

Have you figured out this issue yet? struggling with the same thing on my truck. injector balance is way off bank to bank. no codes though. Although I do have a pretty bad misfire at idle. completely clears up as soon as I hardly tap the pedal. 

[kocheric]

The mechanic at the dealer did some driving diagnostics.  He found no "repair worthy" issues.  He suggested doing extended fuel system cleaner, such as BG 44K for several tanks.  He told me he has seen these types of issues be cleared up by heavy fuel system cleaning.  I have started this approach, but have yet to see much improvement.  My gut says I need fuel injectors, but I suppose I should wait until the issue present bigger issues.

[chamilun]

You need to check misfire data also.  Torque pro can do it

 

But looks like you have an injector issue on bank 2 passenger side.   Id just change them all.  

[Riyadh Baqer]

here having same issues with

any updates with your repairs?

 

[joeybrioso]

Any updates ? 

[kocheric]

The symptoms still persist.   I did have an instance where a random misfire code was stored, and live data once showed cylinder 3 misfires, but only once when applying load when cold.  I ran another balance test a few weeks ago, and the results fall outside general motors 20 percent rule, but I still find it odd that the values are so different when comparing fuel rails.  The results, if looking at each fuel rail are relatively equal.  Why would this pressure drop be so different from each bank, is this the actual issue, and if so, how does it get corrected.  Do these engines, with no drivable issues, show the same results?

[joeybrioso]

So I have a 2018 Tahoe 5.3 6sp with 85k.  I bought it with 55k used from dealer.  When I looks at the maintenance record it shows that the cat was replaced cuz p-0420. Now I’m trying to figure out what cause that code.  During cold star ups and normal operating conditions I currently have a rough idle in park and and at stop lights but runs great when driving.  I’ve been trying to find what is making this happen.  I’ve been to 4 other dealerships in my area many different times and they can’t solve the issue during my warranty period.  One dealership even replaced the engine and transferred all the old parts to the block .  Still same issue.  I have no codes , no air leaks, I replaced plugs , wire, coil, map, maf, pvc, fuel pump, evap, etc.  fuels trims are ok and I’m getting the same results in the fuel balance test.  Bank 1 is lower than bank 2.  My cat temperature on bank 1 is 100 degrees hotter than bank 2 at idle and under load.  I’m thing to replace the injector Now.  Have you change yous ?

Edited January 28, 2025 by joeybrioso

[newdude]

5 hours ago, joeybrioso said:

So I have a 2018 Tahoe 5.3 6sp with 85k.  I bought it with 55k used from dealer.  When I looks at the maintenance record it shows that the cat was replaced cuz p-0420. Now I’m trying to figure out what cause that code.  During cold star ups and normal operating conditions I currently have a rough idle in park and and at stop lights but runs great when driving.  I’ve been trying to find what is making this happen.  I’ve been to 4 other dealerships in my area many different times and they can’t solve the issue during my warranty period.  One dealership even replaced the engine and transferred all the old parts to the block .  Still same issue.  I have no codes , no air leaks, I replaced plugs , wire, coil, map, maf, pvc, fuel pump, evap, etc.  fuels trims are ok and I’m getting the same results in the fuel balance test.  Bank 1 is lower than bank 2.  My cat temperature on bank 1 is 100 degrees hotter than bank 2 at idle and under load.  I’m thing to replace the injector Now.  Have you change yous ?

 

 

Did you use OEM parts?  Are you getting any codes?  

 

I've seen the temp difference from bank to bank on a healthy truck so don't rely on that.  

[joeybrioso]

Yes I use oem parts. No codes at this moment.