EFI University

PLP · Joined: 15 Apr 2007 Posts: 74

Hi all

I have a couple of questions re setting up injectors using SCT advantage software.
I'm from Australia and our ecu's appear not to like the American based value files or ford racings figures even when scaled to suit our fuel pressure differences.
SCT are not very helpful at times answering questions and there appears more knowledge from here so I'm asking here first.

Injector break point
What does this number actually relate to? I understand (vaguely) that this is the point an injector switches from the low slope to the high slope, but what exactly does the number relate to? Is it a reference to rpm, injector pulse etc etc.
Is there a way to measure this switch, I have checked multiple times for a pid to log and can not see one, but sometimes can overlook something obvious if expecting to see something else.

Minimum Pulse Width
I assume this is a number slightly below what the injector will get down to, but is this a limiting figure?, ie
if I set a number there, the injector will not pulse below that figure which means it may run rich at low pulse width numbers because the injector will not go low enough due to the ecu stopping it.
Is this number important?
I'm thinking for a given engine, if larger injectors are used that require a larger low slope, this number should be made smaller as less pulse width would be required fr the same given engine idle speed.

I was thinking about purchasing the CD by Greg Banish as lots of members here have recommended it, but the cd is appears to be gm based and not sure if it would answer my questions or steer me in the correct direction with my sct issues

Interested · Joined: 21 Feb 2010 Posts: 5

Knowing the size of the standard injectors and the size of the new injectors I do a little math and change the standard high and low slope numbers and minimum pw by that percentage as a start point. I usually leave the min PW like that.

For the low slope number I let the motor get up to operating temp and allow it to idle and log the stft and ltft. Sometimes your too far off and need to watch the trend of the stft to get closer into the ball park and reflash. Once it has stabilized i use the ltft number as a percentage to change my low slope number. The short term number if you don't already know is expressed in lambda.

For the high slope number I first do some quick static load checks at a couple of different rpm sites (eg.1000, 2500, 4000rpm) to see if the High slope is not too far off (too lean or rich). Once it's safe i'll do some power runs and check for trends. Usually the first 1 or 2 runs are richer than the subsequent runs, up to 1 ratio richer. My guess is post start enrichment.

Hope this helps,

Davo

edit: The breakpoint as you stated is the switch over point from low to high slope numbers. I believe this is used to characterize the injector flow. At low pulse widths the quantity and/or spray can be inconsistant as judged by the ECU. Once over for example 2ms the injection events have better atomisation and quantities. If you know how to evaluate and determine this number from injector type to type I would like to know too.

tony1 · Joined: 19 Nov 2003 Posts: 108 Location: Dallas

For what it's worth, all this data is supplied with Injector Dynamics injectors. As for where to get it for other injectors, I don't know of anyone else with the ability to test and provide that data so it comes down to trial and error.

www.injectordynamics.com
_________________
T1 Race Development
fabrication/fuel injection tuning and installation

www.T1Raceparts.com
www.InjectorDynamics.com

tony1 · Joined: 19 Nov 2003 Posts: 108 Location: Dallas

Hey guys, here's a more detailed explanation of the Ford terminology.

http://www.t1racedevelopment.com/index.php/en/forum.html?func=view&catid=15&id=193#193
_________________
T1 Race Development
fabrication/fuel injection tuning and installation

www.T1Raceparts.com
www.InjectorDynamics.com

PLP · Joined: 15 Apr 2007 Posts: 74

PLP · Joined: 15 Apr 2007 Posts: 74

tony1

The 2nd post helps undertsanding the terminology

I'm from Australia and injector dynamics are not normally 1 of my suppliers, but I use another supplier who sells and injector called an Xspurt and the sizes appear to be the same as the injector dynamic injectors, they will also supply data showing flow at different pressures and injector deadtime at different pressures, but this does not help me at this stage with SCT data, does injector dynamics supply SCT data and is it accurate (if they do)?

tony1 · Joined: 19 Nov 2003 Posts: 108 Location: Dallas

Injector Dynamics does supply SCT data and it is 100% correct. ID is the only one I know of in the aftermarket injector industry that is capable of doing so.

There are ID dealers in AU.

http://www.injectordynamics.com/stockingdealers.html
_________________
T1 Race Development
fabrication/fuel injection tuning and installation

www.T1Raceparts.com
www.InjectorDynamics.com

tony1 · Joined: 19 Nov 2003 Posts: 108 Location: Dallas

I see that you've mentioned Greg Banish, he has used and tested the ID injectors and GM and Ford data.
_________________
T1 Race Development
fabrication/fuel injection tuning and installation

www.T1Raceparts.com
www.InjectorDynamics.com

PLP · Joined: 15 Apr 2007 Posts: 74

Hi Tony

I have responded via email.
None of your dealers are in my state and the only one on that list that does fords is Xtreme. Can he supply the SCT data or is that a dealer by dealer thing?
I sent Greg and email on another froum that he frequents a week ago and so far he has not responded