Gentlemen, I have a PCMforless tune for 36# Bosch injectors.
Can I run this same tune with 36# Lucas injectors, or 36# Sieman Deka injectors?

Thanks, Dean

 

The PCM should be able to compensate for the different types of injectors.

That said, I don't know why you don't invest in a Tuner Cat or LT-1 editor program ... it's not all that difficult to do the simple stuff.

Hope this helps

LWM

 

Thank you sir.
That's good news cause I just bought some Delphi/Lucas 37#'s from Thunder Racing for $299.69 during their Labor Day sale. Best price on the net.
Hurry, won't last long!

Later, Dean

 

it all depends on the psi they are flow tested at. if the old ones you had are 36# at 50psi thats fine. but if your new are 36# at 40 psi and you put them in, that would be like at 45# injector. and the pcm will never correct that much, and its not wise to let the pcm correct for fuel injectors becuase, if it the case was like i stated above the pcm would try to correct and your blms would go to 108 meaning its taking all the fuel out it can becuase your runing overly rich. and it may be enough to was the rings out.

it all depends on what pressure they are to be run at and what pressure you will be running them at. if they flow test at the same pressure it should be a easy swap out.

this where editing software comes in handy, becuse if they are different all you do is change the injector constants table.

by the way the pcm corrections are not designed for injector changes its designed to make changes for the air coming in, wether it be cooler or more humid the pcm see this and using several sensors will make correction. but the pcm will never make changes big enough to compensate for injectors.

the pcm margin for correction is very small.

do a little research on the new injectors and see if you will need a tune or not. but dont through them in and hope for the best, that might cost you a engine.

 

All the injectors I considered were rated at 43.5 # fuel pressure.

Thanks, Dean

 

A little more information I picked up from .... who knows where, but this is what it is.


SVO Injectors were rated at 39.2 PSI. Our cars run at 43.5.
The formula for figuring out the new flow rate is:

newflowrt = sqrt(newpress/oldpress)*oldflowrt


So if you had SVO injectors, and you are changing to another type ...

= sqrt(39.2/43.5) = 0.949

So you would be looking at a 5% difference in "apparent" injector size. You could adjust you fuel pressure accordingly. If you simply swapped out the injectors without doing anything else you may run a tad lean, but the computer would adjust for that.

The LT1 editor software has a function that lets you monitor the fuel trims so that you can adjust up or down in small increments the injector size to attain the much sought after 128 fuel trim.

Anyway, I used 30# SVO injectors for a couple of years without any correction for the fuel pressure difference ... no problems.

FWIW, I'm now running SVO 42# injectors at 50 psi of fuel pressure, and in the LT1 editor I call them 48# injectors ... runs good.

LT1 editor or Tuner cat ... you can't go wrong.

Hope this helps

LWM

 

Thanks LMW,
You're always a big help. So using your formula a Bosch 36#'er will flow 37.8#'s @ 43.5 psi. The Delphi/Lucas 37#'ers I just bought are rated @ 43.5
psi. Looks like I got lucky again.

Dean