bjankuski

I am trying to program a 1985 vette and the injectors have been switched from the stock 22LB to 36LB injectors. I am using tunercat and I have the correct definition file but I do not see any place where the injector size is entered. On the 1986 and up tunercat definition file there is a injector size that needs to be entered. Can anyone tell me what I need to change to use the 36LB injectors?

Thanks.

Swirk

Did you look in the ECM constants table? That is where mine was. I used Tunercat to do mine.

gbody5

I use TunerPro, for an 88 with 165 ECM the single fire and double fire Fule Injector size is in the constants at location 3D6 and 3D8 respectively. Look for a similar name and location in the Tunercat constants.

dgoodhue

I don't have an 85, but I remember reading their is a way to do it (but its not obvious either like with 165). I would try searching the thirdgen.org. My truck has an offset table that you can use for injector sizing.

tjwong

Thats an awful large injector to use on a L98. What are your other mods? Do you really need this large of a flow rate. The reason I ask is because your system is a bank to bank fired injection system meaning that one bank of four fires then the second bank fires. This happen every crank revolution. If you had a sequential fired system you have much better idle stability and control because one injector fires with each rev in the firing order. But to answer your question you have to scale the injector size in the table named "injector Pulse width vs load value"

I would take the old injector size divide it by the new injector size or 24/36 = .666

Then use that number to scale the injector PW table. Having larger injectors means that you would scale the PW table to a smaller number to compensate. In the later 86 and up ECMs there is a constant for the injector size in the constants table. Scaling that table will get you well within the ball park. Final tuning should be done on a chassis dyno with a wide band.

bjankuski

Thanks for the replies.

The engine is a 383 Superram combination that has similar parts to the engine in my sig.

Brian

tjwong

Brian for your mods I would really consider sticking with 24lb injectors. If you need a little more then just raise the fuel pressure a little. 24 pound injectors have proven themselves to provide enough fuel for 10 second drag cars such as Ski's and Corkvettes cars. I have a couple stock eliminator cars running 10's using 19s and 24s. Both are LT1 F body cars.

gbody5

Well, learn something new everyday. Thanks!

GRX

Brain, nobody mentioned that 85s came with 24lb injectors...just a clarification...

B84RADR

You'll be fouling spark plugs right and left with anything bigger than 24#. I know I was with 30's. I had to get rid of them because they were getting carbon fouled after about a tank of gas!!

Shayne

B84RADR

And to follow up on that, on my '85 I contacted TC and they provided me with a definition file to adjust for the pulse width so that my MPG and DTE were correct.