Acceptable LTFT variance between banks?
Thread Starter
TECH Resident
Joined: Nov 2002
Posts: 996
Likes: 0
Acceptable LTFT variance between banks? I'm getting ready to install EFI's custom 2-bar OS on my boosted Z06. I have noticed that my LTFTs pretty far off from each other (Bank 1 and 2).
Bank 1 was always slightly higher, but now on Decel, and idle (High Vacuum Moments), Bank1 is about 7% leaner. During Acceleration they are about dead even, so I figured a vacuum leak is probably to blame. I recently insaled 60 lb injectors with the turbo install, and it looked like some where not seated as deeply as other in the stock LS6 manifold. I even heard a vacuum leak coming from one of the injectors O rings in Bank 1. The solution for me was to bend the fuel rail mounting points, and now they all sit in deep, and no more leaks (99% sure of that!) I thought for sure that was why Bank 1 was running leaner.
BUT bank 1 is still running leaner. I even switched the O2s from left to right, same thing. I'm thinking about switching the injectors from one bank to the other, but since the LTFT variance only really occurs at idle, and decel, and steady slow to moderate speed (high vacuum), I still think it is a vacuum leak.
Any ideas, and is 7% even anything to worry about?
Thanks for any info.
Tommy
Bank 1 was always slightly higher, but now on Decel, and idle (High Vacuum Moments), Bank1 is about 7% leaner. During Acceleration they are about dead even, so I figured a vacuum leak is probably to blame. I recently insaled 60 lb injectors with the turbo install, and it looked like some where not seated as deeply as other in the stock LS6 manifold. I even heard a vacuum leak coming from one of the injectors O rings in Bank 1. The solution for me was to bend the fuel rail mounting points, and now they all sit in deep, and no more leaks (99% sure of that!) I thought for sure that was why Bank 1 was running leaner.
BUT bank 1 is still running leaner. I even switched the O2s from left to right, same thing. I'm thinking about switching the injectors from one bank to the other, but since the LTFT variance only really occurs at idle, and decel, and steady slow to moderate speed (high vacuum), I still think it is a vacuum leak.
Any ideas, and is 7% even anything to worry about?
Thanks for any info.
Tommy
Thread Starter
TECH Resident
Joined: Nov 2002
Posts: 996
Likes: 0
Originally Posted by oange ss
it's normal to have some variance between banks, mine does the same thing but not 7%
Tommy
The skinny 60# are Mototron injectors. I would take them out and get them flow tested and possibly cleaned (sonic-ly). RCengineering will give you a datasheet to each injector.
Dixit
Dixit
Originally Posted by TaTommyWS6
I switched the left and right injector banks and the problem follows the injectors. I guess I found my problem (now I need to find a solution!) They are 60# injectors that came with my twin turbo kit. Maybe I need to try another set, or another brand. I am not sure what brand these are. They are very skinny, black injectors (if that description helps!)
Tommy
Tommy
Thread Starter
TECH Resident
Joined: Nov 2002
Posts: 996
Likes: 0
Originally Posted by bshell
I know that sending the injectors in for a cleaning and flow testing is the best way to go, but I wonder if you would be able to mix the injectors to even out the trims. Maybe switch every other injector from bank to bank to see if your trims level out? Could buy you some time at least until you get some other injectors in there...
If I wanted to get them flow tested, I just send them out via the mail? What is the turn around time?
Thank for all the info.
Tommy
Trending Topics
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo Mototron injectors are definetely good quality injectors. Turn around time would be best obtained by the place you choose to do the flow testing and cleaning.
Also was your Injector vs MAP table tuned correctly?
Dixit
Also was your Injector vs MAP table tuned correctly?
Dixit
Thread Starter
TECH Resident
Joined: Nov 2002
Posts: 996
Likes: 0
Originally Posted by Ragtop 99
Have you called the shop that sold you the turbo kit? Maybe they'll swap injectors with you if they are new.
Just as an aside, lets say I get the injectors flow tested, and if a few injectors are clearly not within the same limits, what is the next course of action? Replace just those few injectors? Of can they be tweaked to flow the same?
Thanks again for all the info.
Tommy
PS A twin turboed Z06 is absolutely halarious to drive!
