Question about bigger injectors with stock ecu
10-03-2009, 04:42 PM
#1
Question about bigger injectors with stock ecu
I want to run bigger injectors on my turbo set up. I have the greddy kit + intercooler + wallbro 250 pump. If I install these :
1989-92 TOYOTA SUPRA 3.0L Fuel Injector OEM Fuel Injectors, Diesel Fuel Injectors
Does the gas get injected based on the pressure or the amount flowed? What I'm getting at is should I lean out the afm so less gas pressure is forced in so it doens't run rich with the bigger injectors, or richen it on the afm so that more gas is flowed through since the injectors are bigger? (All this is assuming that this will work without aftermarket ECU.) Thanks for any help!
1989-92 TOYOTA SUPRA 3.0L Fuel Injector OEM Fuel Injectors, Diesel Fuel Injectors
Does the gas get injected based on the pressure or the amount flowed? What I'm getting at is should I lean out the afm so less gas pressure is forced in so it doens't run rich with the bigger injectors, or richen it on the afm so that more gas is flowed through since the injectors are bigger? (All this is assuming that this will work without aftermarket ECU.) Thanks for any help!
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10-03-2009, 10:49 PM
#3
Boost Pope
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What a patient man you are, waiting nearly six hours, and on a saturday, no less. 
According to This Sticky. the 89-92 green-top Supra injector is rated at 305cc/min, vs. your stock injectors at 230cc/min, so that's about a 30% increase.
I'm not really sure what this is asking, but I'll try to interpret.
The Miata's ECU does not read manifold pressure. It bases its injector puslewidth calculation entirely upon the signal coming from the airflow meter. Is this what you mean by "the amount flowed"?
To run this injector on a stock ECU, you'll want to tighten up the clockspring in the airflow meter a few notches. It's unfortunate that with the non-OBD2 cars you have no way of knowing what the O2-based correction percentage is, so it's pretty much pure guesswork.
According to This Sticky. the 89-92 green-top Supra injector is rated at 305cc/min, vs. your stock injectors at 230cc/min, so that's about a 30% increase.
Does the gas get injected based on the pressure or the amount flowed?
The Miata's ECU does not read manifold pressure. It bases its injector puslewidth calculation entirely upon the signal coming from the airflow meter. Is this what you mean by "the amount flowed"?
To run this injector on a stock ECU, you'll want to tighten up the clockspring in the airflow meter a few notches. It's unfortunate that with the non-OBD2 cars you have no way of knowing what the O2-based correction percentage is, so it's pretty much pure guesswork.
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