Here is my situation. I just installed a new engine for someone and i put some 850 injectors in the primaries. So i went to the injector setting and put 850 to the primaries.

it really looks like it doesn't work because the car is running way to rich at idle. So i went and put the injector% at 65 for the primaries and everything came ok.

So i decided to do some test and decided i would write anything in the injector cc, i tried both 100 and 1600 and none had any effect.

I thought that when you changed that setting in either the datalogit or the commander, the Power FC made the instant calculation since he now knows he's got other sized injectors.

Chuck? Is that normal?

Does that mean that when you install 1600 in secondary just changing the injector setting from 850 to 1600 isn't working?

thanks a lot

 

For the primaries, you have to enter size and size ratio percent.
550/850 = 64.7%.
For the secondaries, you only enter size.
For both you have to enter lag difference.
All of this is well explained in the PFC and Dl manuals.

BUT since the PFC can not run the 850 primaries as lean as they need to be at idle, you have to use less lag to lean them out which will require you to retune everything to compensate.

I have never full tuned an engine with 850 primaries to see how messing with the values totally affect it. But I am about to do it and test.

Example: 850 with about -.04 lag which is common might flow like 700-750cc.
So maybe those values should be used so the internal math conversion works.

Hopefully I'll find out.

 

^^ great info. thx. since the subject title is still relavant, i'm gonna thread jack a bit..

chuck,
what about secondaries? do i need to change both the injector size setting and % or will it self adjust % to your injector size? i've never done injector upgrade with a PFC and preferably i'd like to drive my car to the tune .. or do i need to get it towed to the tuning session after i drop them in? thanks in advance

 

^not chuck but, there is not place to change the % for the secondary inj. If you change the secondaries all you do is change the size.

And for the first guy. It's not going to hurt it to idle at ~10.5/1, there are good many people who's car does that, including me. It does make for a stinky garage if you let it idle or tears if you stand behind it very long.

 

it actually wouldn't hold idle, it would die being too rich.

I do not have the datalogit manual unfortunatly, bought it used.

Chuck, mind developing a little bit about what the lag effects exactly? I must admit i am not really sure.

thanks for the help guys.

 

When the ECU commands an injector to squirt, there is a split second lag for the gas to actually make its way out through the tip. Larger injectors have longer lag.

With our PFC, lag adjustment also affects total fuel flow as this affects total injector open time. Thus when you go to negative lag for a leaner idle with 850s, it reduces the total open time from what it should be with normal lag.

 

doesn't it also reduce the flow capacity the injector can give? I mean if i understand correctly it will reduce the duty cycle that is available for one rotation for example?

I understand it will help reduce the excessive fuel flow at idle but wouldn't a change in the map do the same job? If you change that lag time, you say it might flow like a 700-750, wouldn't it flow like that also at high boost, where the 100cc missing might be usefull?

Damn i like talking with knowledgable people, finally, i learn something usefull

 

awsome. thanks for the info