injector swaping

there are no efi systems that i have ever heard of that automatically adjust for bigger injectors. the computer needs to know how much fuel is going through the injector when its pulsed.

some how i was thinking that the 02 sensor on a 20 year old EfI system was going to have a major effect on pusle width. just needed some one to tell me yes you are being a tard. my answer sure you can run 14psi without being lean but itll be rich always

-Pete

Actually most do, to an extent. :lol:

If the injectors are within the LTFT's perameters, then it can sense the increase in fuel and trim it back. :wink:

Most people claim about 10% control for the ecu. So 270cc injectors could be replaced with 300cc injectors (approx) and still do a closed loop around the O2 and achieve near-stoic. They would probably be always pushing on the rich side, and may not pass emissions, but you will get a decent idle.

But some poeple here also claim that the ecu does not learn this, and therefore the open loop conditions would be 10% richer. In other words, it will inject the fuel as per the program in the ecu.

So if you want to have a nice idle, you might try that. But it will not help you with those boost goals.

A trick to help out the slightly rich condition from the 300cc injectors at idle would be to trick-out the fuel temp sensor. Change this so the ecu thinks the fuel is cold. It will lean out the fuel a bit since it thinks it is dense. This would help the idle. But there must also be a mechanism to change this so the ecu thinks the fuel is hot during boost. The ecu will enrichen the mix then.

Even combined with something like a rising rate fuel pressure regulator, and with slightly larger injectors, you will run into a limit. The stock ecu will only open the injectors for only so long a duration. This 'ceiling', and the max fuel flow, is the maximum you will push the ecu's limit.

The Z31 already runs quite rich under boost. I would be very cautious about going larger on injectors and hoping it will compensate under any condition.

Lets just say you can get a little more fuel out of the stock injectors and that larger ones w/o other changes is not a wise idea.