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View Full Version : A thought about fuel injection



timetowinarace
07-16-2008, 07:11 PM
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
07-16-2008, 07:21 PM
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
07-16-2008, 08:13 PM
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
07-16-2008, 09:09 PM
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
07-16-2008, 09:54 PM
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
07-16-2008, 10:09 PM
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
07-16-2008, 11:02 PM
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
07-16-2008, 11:58 PM
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. :D

ranger2.3
07-17-2008, 02:42 PM
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
07-17-2008, 08:53 PM
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.

Bigtoyota
07-17-2008, 11:10 PM
Well, the ECU can adjust injector pulse width to compensate for less pressure or smaller fuel injectors. The heart of the problem lies in the fact that the ECU itself is not programmed for HHO. Period. Anything else you do to it, O2 spacers, MAF adjustments, are just band-aids for the problem.

Until you can reprogram the fuel and timing curves of the ECU itself, this will continue to be a problem.

However, one band aid that I have thought of recently I have used on a car. I replaced the O2 sensor with a black box, programmed to give the ECU a "everything's OK" voltage reading. The reason for this was he got a header with no O2 sensor bung welded in. Rather than go get a bottle of gas and a spool of wire to weld in ONE stainless bung, we just deleted that O2 sensor from the equation.

I think this is probably the best way, short of reprogramming the ECU, to get better mileage with HHO. With the box, the computer is receiving a steady O2 reading, therefore keeping the fuel air ratio the same. On vehicles with more than one O2 sensor, you would probably have to replace all of them.

I am currently in the process of building my own HHO generator to test out on my 1986 Toyota EFI pickup. This pickup is OBD 1, therefore it's got the dumb computer in it, and should benefit more from the HHO. Once I have fine tuned the generator and my truck, I'll proceed on to my 2003 Honda Civic with OBD 2, and see what hurdles await.

parkerbuckhunter
07-18-2008, 02:28 PM
Here is my two cents which is probalbly less thanks to the falling dollar. If I understand things the way I think I do the auto manufacturers have determined that a a/f ratio of 14.7:1 is the optimum safe threshold that the computer should always try to maintain. If the engine runs lean then the computer opens injector and vice versa in rich state. This should be old news to most here but If there was a way to reprogram the computer to try to maintain say a 16:1 ratio instead of 14.7:1 than you wouldnt have to cheat anything. The computer would automatically do its thing as long as there was HHO being supplied. I am sure some one out there is able to do this but I am not one of them.
The answer to unhooking the O2 is that the computer automatically defaults to a safe mode which happens to run the engine on the rich side so it wont burn up thus using more gas.

Bigtoyota
07-18-2008, 04:24 PM
That's what I've been attempting to preach here and elsewhere. The fuel and timing curves in the memory of the ECU needs to be replaced with different maps to accommodate HHO and gasoline mix. I believe Smith is on the right track with his testing on his VW. He is fortunate enough to have a laptop to hook up to his car and actually see what is happening. Hopefully this will lead to a new map for his ECU, and we can see for sure if this will make a difference.

Smith03Jetta
07-18-2008, 04:45 PM
I hope to get this working but it's sort of like a slow trial and error process. I may do some serious testing this weekend. I've only been able to test drive to and from work this week, making some tweaks in-between. Once I get it right, I'll post timing and fuel system tweak recommendations. Finding an ODB-II cable and software for your particular vehicle will be up to you. If you have an Audi or VW or Skoda, I can help you. Wish I could do more.

dhho
08-06-2008, 07:28 AM
Bigtoyota that blackbox that gives the all ok signal sounds like a great device and should give same results as a carby car provided you inject hho after other sensors.Do these things have a name and where do you get them? I recently added hho to a friends tray top carby type and she is getting 30% better milage.
Regards,
Mos

Smith03Jetta
08-06-2008, 11:49 AM
I have an update. By manipulating the Adaptation channels on the ECU, I have been able to effectively lean out my engine to achieve some gas mileage results. I tried several things but eventually I came back to the following settings.

I changed the Acceleration adaptation channel from 100% to 98.5%.
I changed the Deceleration adaptation channel from 100% to 94.5%.
I changed the Secondary Fuel adaptation channel (Additive Fuel) from 100% to 98%.
I changed the Primary Fuel adaptation channel (Multiplicative Fuel) from 0 to -19.5% (Negative). If you think about it the purpose of adding HHO is to allow you to lean out your fuel mixture or in plain English (Use less gas per mile). The max ranges on this adaptation channel are -25 to +25.

I did not really see significant gas mileage savings until I surpassed -15% on my Primary Fuel Adaptation channel. After 15% I started to see my gas mileage go up. My last post was 32 mpg with the AC on, mixed city and highway mileage. Highway speeds about 65 mph average. Hot days, no rain. Tire pressure about 5 psi above recommended inflation.

I also adjusted the Lambda sensor timing to return a signal faster. I also raised the speed limiter to it's max. Most passenger cars have a 115 mph speed limiter. I can now drive 78 mph/127 kph faster than the old factory speed limiter. If I need to outrun somebody, now I can do it. Assuming I have the horsepower. I might want to richen up the mixture if I plan to go fast. I don't want to go into detonation. The Ratio of HHO to gas would be pretty thin at Higher RPMS.

I did two intentional adustments to richen up the startup fuel mixture and the warmup fuel mixture. This will help keep the engine from starting and warming up in a lean condition until the HHO starts flowing at a decent level. After I changed these settings I noticed that the engine started better in the mornings. After the engine starts up I notice a power drop as the fuel leans out followed by a noticeable change for the good in throttle response.

I did not adjust the ignition timing offset. I tried adjusting this in both directions but I either got loss of power, loss of gas mileage, rough running engine, misfire or valve noise.

Cadillac
08-14-2008, 03:05 AM
One thing that is being over looked is how injectors are rated. A manufacture only rates the flow up to 85% of it's maximum capacity (sometimes not even that high). If you just went to smaller injectors it would still have the availability to deliver the same amount of fuel as the stock injectors.

It is pretty common knowledge with guys into forced induction systems that you can use the stock injectors for up to 8 pounds of boost provided you up the fuel pressure. The elevated fuel pressure is just for the higher rpms. The longer the injectors are open the less fuel pressure so you have to do something to compensate for this or let it lean out melting the piston in the cylinder.

Clayne_b
08-14-2008, 09:47 PM
Ive been reading ALOT on this forum.... and im going to build a pretty big set up for my 1992 Dodge Cummins. Its is pretty much all mechanical, fuel pump. Im wondering if you guys think i will have to adjust anything. or can i pump all the hho i can make into it. Im shooting for 3 lpm.