what would happen if i put in bigger injectors without an ecu?

i have a downpipe and an intake.

 

You'll dump too much fuel into the system and the car will run extremely rich and extremely bad. You'll also run the risk of washing the oil away which will increase wear.

 

Exactly. Why do you think you need bigger injectors?

 

Injectors work by opening a small valve for precise moments of time. (Duty cycle is the fraction of total time they are open). The ECU controls how often the injectors should be opening.

Bigger injectors mean bigger flow in that time period. Since the ECU doesn't know that, it doesn't change the injector commands, and you get much more fuel than necessary. Even going from a 600cc to 850cc injector would cause extremely rich running conditions. (Do the math, that would be 25% more fuel, and make an 11:1 afr into like an 8:1, and 8:1 is pig disgusting dripping rich).

Experts please correct if I'm mistaken.

Dave

 

Don't bother getting larger injectors if you've only got an intake and DP. The stock ECU runs pretty darn rich WOT (even with an intake, DP, and catback) so long as you don't exceed the stock boost levels. You can get away with the stock injectors (but upgraded ECU) up to around 320RWHP I think.

 

ok, thanks guys...i'm just doing the vacuum job soon, and one of the right ups suggested getting the stock injectors blueprinted...so i thought..."hmmm, maybe i can just get new ones"

guess not.

thanks for the info

 

You can get new ones, but you should just get stock injectors. Blueprinting isn't too important - it's the cleaning that counts. That can make a real difference. 'Blueprinting' costs just a little more to check the improvement in flow.

Dave

 

What about a supra fuel pump on a stock ecu?

 

Shouldn't be a problem as long as your FPR is working (and able to handle the pump). The FPR is what regulates fuel pressure. So, as long as it's working properly, if you increase your fuel pump only the same amount of fuel is allowed past the FPR.

 

I think that most of the folks that "service" FIs, do both, clean and flow/balance/calibration/pattern test/blueprinting. Had mine done (on my 104k injectors) by RCEngineering and it had a HUGE impact. Not only was the car significantly smoother, but it also picked up a good 7 mpg! I'm sure new injectors would have done the same (maybe even a little better), but servicing the old ones is significantly cheaper...