fuel ecu trick

[Guest HBZ81]

mod please move to misc tech

 

I was clicking through sites about SVXs and I found this. It's a way to trick the computer into letting you use larger fuel injectors with twice the amount of air coming in, but not having to reprogram the ECU. Do you all think it could work on any fuel injected cars?

Fuel

For modifications' date=' the fuel pump is a monster (222lbs/hr) meaning it could support about 444 horsepower at .5 BSFC. Unfortunately, the injectors are a different story as they are 275cc jobs that are going to be maxed out at 250 HP. If you mount a turbo or do some other modification that would cause your injectors to be inadequate, you will need to upgrade the injectors. This also requires a re-tuning of the ECU. But, you can easily support nearly 500HP by using the following trick. Buy the Nissan Motorsports 555cc injectors. They are expensive, but they will bolt in. Replace the pipe from the air filter to the intake with two pipes; one for opening in the throttle body. Plumb the mass air sensor into one side so it only supplies one bank of the engine. You will have to supply a separate air filter to the other bank. You have now effectively halved the amount of air the ECU sees, while compensating by doubling the amount of fuel injected. This has the added benefit of reducing the intake pressure drop through both the meter and the (now) two air filters.

I have done this trick on two other cars with success. However, I have not done this with the SVX. Some ECUs will compare the A/F readings against a known map and decide the air sensor is bad. Others (particularly the Ford EEC-IV) have no problem at all. I also did this with a Subaru RX Turbo with no problems. Best to disconnect the battery overnight before trying this trick to force the ECU to reset.

If this sounds like too much work, buy the Infiniti Q-45 370cc injectors. They will also bolt in (and are cheaper). Add the very slick Apex-i Super AFC fuel computer and decrease the air meter readings by about 30%. This will allow you to support 350HP. This also provides you with control over the entire fuel map.

Of course, unless you do something more than exhaust and intake, you'll never need to do any of this. [/quote']

Now I know it's for the SVX, but I think may be a lot of cars can use this method. Probably most pre-OBD2

 

mod please move to misc tech

[dosquattro]

Ehhh... Thats kinda like saying add a resistor to the signal coming to the ecu from the MAF could it would only see half the voltage. Like that ebay mod that people were selling and it was only to reduce the voltage coming from the intake air temp sensor and making the ecu think it was see cooler air. How is splitting the amount of air gonna scale down the injectors so it won't flood out the engine just idling or normal driving?

[TheNeedForZ]

A member here has done something like that before but I cannot remember who it was. He removed the Z31 MAF sensor component and put it into a larger pipe housing.

 

The car will not have problem idling or normal driving *IF* the ecu always provide fuel according to MAF reading. The question is that since all air speed is reduced by half, will MAF reading still be accurate at low air flow?

[ProjectSR20]

In my experience, the only thing you get out of something like confusing the ECU is a rich running motor and horrible gas milage. It would be worth your wile to get some form of engine management system. I would be too concerned about the accuracy of the A/F ratios. If you are running 15+ lbs of boost and suddenly get too lean, you are sitting on a grenade.

[mtcookson]

A guy did something similar on a turbo 240SX by putting the maf sensor into a larger pipe. Doing that tuned the car better than a JWT ecu tune. I bet doing that and adding an Apex'i S-AFC II or similar would give a pretty decent tune.

 

I'd highly recommend getting a wideband o2 sensor setup when doing any tuning like that though. Knowing right away what afr you're running will save you time and time again.

[AK-Z]

I don't think that would work for a L6 or a L4 motor. From what I understand from what I've read, you are decreasing the air flow that the ecu sees by placing the MAF sensor on one side of the intake (v6, v8, I4, I6 engines).

 

Doesn't really matter because most of our ecus are stupid and don'y really have a problem with switching injectors.

[John Dixon]

Going to do wonders to the timing maps ......

[big-phil]

I've got stock ecu and bigger injectors. all I did was tighten the spring on the flapper in the AFM. Thats probly the same idea. The ecu thinks it getting less air