A thought about fuel injection

[timetowinarace]

So, I was thinking of all the problems every one is having with ECM's, MAF's, O2 sensors and whatnot. In carborated vehicles the answer is simple. Change the jetting in the carb. Smaller jets = less fuel no matter what the ECM says. Problem solved.

What about injectors? For people like myself with the '06 cummins, I can put smaller injectors in. They make a wide range of them for different purposes. Marine applications with the same engine that is in my truck uses much larger injecters. Go back a few years and the stock injectors are smaller than the current ones. Also, most of the performance 'chips' or 'programmers' change the timing and duration of the amount of fuel the injectors spray into the intake. My Bullydog programmer does this. So just what am I getting at?

Many of you are spending considerable time trying to stop the various sensors from sending the signals they were designed to do. So far, from what I have read, there has not been a whole lot of success to this approach. It seems to me there might be better options. Smaller injectors is one option for some engines just like using smaller jetting in a carb. Another option for some may be to simply reduce the fuel pressure. Less pressure means less fuel pushed through the injector. Splice the fuel line with a short piece of smaller diameter line. Or another option for some may be to shorten the duration on the spray from the injector. This would be done electronicly and may even be simple, I don't know.

Details of this thought of mine are not available. It is just a thought. And better yet, (a rarity on this forum, most of the ideas, designs, and theories presented here are awfull familure most the time) I probably read the idea elswhere and just can't remember where.

At any rate, less fuel is the desired goal when sensors tell the ECM that more fuel is needed. Why not leave the sensors and ECM to do their thing and just limit the fuel that is available? Is that putting it simply enough?

[daveczrn]

It's not that easy with EFI engines. The computer doesn't care what you have in your engine. What it wants to know is if the 02 sensor is seeing the right amount of oxygen in the exaust. If it does not it will compensate by either richening up the mixture or leaning it out. In the case of either a smaller injector or less fuel preasure the computer would try and overcome that as well. It will to a set point in the computer and then it will go into limp mode where it just dumps fuel into the engine and ignors the sensors. your fuel economy will go out the window when this happens. and it will throw a check engine light

[timetowinarace]

It's not that easy with EFI engines. The computer doesn't care what you have in your engine. What it wants to know is if the 02 sensor is seeing the right amount of oxygen in the exaust. If it does not it will compensate by either richening up the mixture or leaning it out. In the case of either a smaller injector or less fuel preasure the computer would try and overcome that as well. It will to a set point in the computer and then it will go into limp mode where it just dumps fuel into the engine and ignors the sensors. your fuel economy will go out the window when this happens. and it will throw a check engine light

Sorry, but the way I see it, me, you, nor a computer can push all the water from a garden hose through a straw. Restrict the flow of fuel = lean out the mix. CEL will come on. So? If your messing with all the sensors then that safety feature(CEL) becomes mute anyway.

You are correct that the computer will TRY to make the mix rich. That is precisely my point. The computer will TRY to make it rich but unless it can pull the injectors out and put the originals back in, then all it can do is TRY.

Risk factor: If your electrolyzer quits your car will run lean. Too lean for very long is bad, bad, bad.

[daveczrn]

Sorry, but the way I see it, me, you, nor a computer can push all the water from a garden hose through a straw. Restrict the flow of fuel = lean out the mix. CEL will come on. So? If your messing with all the sensors then that safety feature(CEL) becomes mute anyway.

You are correct that the computer will TRY to make the mix rich. That is precisely my point. The computer will TRY to make it rich but unless it can pull the injectors out and put the originals back in, then all it can do is TRY.

Risk factor: If your electrolyzer quits your car will run lean. Too lean for very long is bad, bad, bad.

exactly. The computer has a adjustability of about 25% that it can adjust from the standard baseline depending onthe sensor results. If there was a problem you will have engine troubles. I believe it would be better to adjust the a/f radio with either a piggyback efi system or something else.

to rely on the limp mode to add a exact amount of fuel for the engine i believe you would be have problems just from the get go.

[Stratous]

Most vehicles have an atmospheric pressure sensor, adjust that and make the vehicle think its at a higher altitude that what it actually is.

[wurkenman]

Most cars today are nothing more that computers with wheels. The ecm monitors all functions and if the fuel pressure drops below preset specs you will still see a trouble code.

[mikestrikes]

Yeah and if you put a smaller injector on it to the point its the limmiting factor to get the correct A/F ratio then when that big rig truck try's to run you over you cant go any faster as you dont have anything left to give it !!!!

Not cheaper or easy, but I could take out all the electronics from my 98 Honda and make a manifold to mount a 2bbl carb and run a regular distributor and be able to work on the dang thing like the old days, add what the heck ever you want and not worry if the car with crap out on you and so on.... Lets go back to the old days of carbs and points and working on out own stuff..........

[timetowinarace]

Most vehicles have an atmospheric pressure sensor, adjust that and make the vehicle think its at a higher altitude that what it actually is.

I'm allready at a higher altitude. My horses have an advantage the first couple of weeks they run in california.

[ranger2.3]

What if you disconnected the O2 sensor? Would it start then? Would you get better or worse mileage? Would it screw up the timing or the ECU?

[timetowinarace]

What if you disconnected the O2 sensor? Would it start then? Would you get better or worse mileage? Would it screw up the timing or the ECU?

It would run rich, worse mileage.