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Anonymous asked in Cars & TransportationCar MakesAcura · 1 decade ago

How to make larger injectors work on a stock ecu? will chose best answer?

I cant chip/tune my automatic integra, so I have to use a stock ecu. I know turbochargers need more fuel but how can larger injectors work without a chipped ecu?

Can I just buy a FMU or a FPR and manually raise the fuel pressure? Will the larger injectors work then? Or can I just raise the fuel pressure on my stock injectors?

Im only planning to run 4psi on my stock b18b1.

Will chose best answer for any help thanks

4 Answers

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  • 1 decade ago
    Favorite Answer

    The only way to modify for bigger injectors is to tune the ECU. The best way to do it is to spend the money to get a Hondata S300 ECU, which will work to control larger injectors and your automatic transmission. This way, you can run as much as 7-8psi as well. The other option would be with stock injectors and using an 8:1 or 12:1 rising rate FMU, which essentially just raises fuel pressure at either an 8:1 or 12:1 ratio of boost pressure. at 4psi, even the 12:1 wouldn't do you much good, as the final fuel pressure would only be 48psi (12x4). At 8psi, however, you can see the effect, as the fuel pressure would be around 96psi, which would increase the volume of fuel injected through the stock injectors. The only problem with this, is it puts a tremendous strain on the injectors and the fuel pump, and it's imprecise at best. As I said, I'd recommend getting the Hondata S300 which is an aftermarket ECU board with full tuneability and functionality that fits inside the stock ECU case, and is the only aftermarket solution compatible with the automatic. Now if you really wanted to jury rig it, you could use an air-fuel controller, like the A'pexi S-AFC, which is popular with DSM owners, but it is pretty imprecise because of the way it works, intercepting signals to the stock ECU and modifying them to get the results it wants. In some situations it works well, but it's just easier (not to mention nobody will see the giant fluorescent blue display to give away the turbo if you want to go stealth and black out the intercooler as well) to get the S300.

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  • 1 decade ago

    it's not that you need the rising rate FMU or anything like that, you will need a way to trim the fuel output at idle and normal driving conditions. Also 4 psi is not even worth messing with as this isn't really enough to even get most turbo's to make any power. Even the smaller T3/T4 turbos start making power in the 7-8 psi range. At 4 psi you will make about 20-25 more HP than what you have now. So for about $3,500 you gain 20-25 HP. But anyway, look at it like this, your injectors from the factory are controlled by the ECU to work, let's say, during normal driving conditions (NDC) for 50% output and 90% at wide open throttle (WOT) so lets say your factory injectors are 240cc during NDC you are using 120cc of fuel and WOT you are using 216cc of fuel. Now you add say 550cc injectors, the factory ECU is still going to tell the injectors the 50% and 90% so now you are going to be using 225cc during NDC, and 495cc during WOT, so at idle and NDC you will be using MORE than what the car requires when the smaller injectors were pushing at WOT and just flooding your engine and making it impossible to drive.

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  • 4 years ago

    Without knowing what car it is it's hard to answer except to say, the fuel pump isn't connected to the ECU in most cars. The fuel level sensor is connected and again, in most cars that is separate from the pump.

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  • 1 decade ago

    it depends on how much larger the injectors are, and how much extra fuel you need. a small amount can be handled by an FMU. however the nest way is to recalibrate the mass air sensor, assuming your system has one, to handle the large injectors.

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