hho modification

[Ultra]

Hi everyone.
I'm driving 1995 Impreza Outback Limited Edition, with 1.8 engine and stick shift =).
I've seen a lot about hho modification to the vehicle, and I wanna try to do it myself. But i Might need some of ur help here. =) After doing each of the steps, i'm going to blog it here with my results.
---
1st question. One thing that is very recommended is to trick your oxygen sensor. What voltage does it run of? I want to wire a potentiometer in the signal line, to trick ECU, so it will inject less fuel.

THANX

[I Like It Sideways]

Interesting, I haven't read much about that.

I'm not sure what voltage is used by the oxygen sensor either. Guess I'm not much help :(

[Ultra]

My guess would be 12 V, but would probably need to go down my impreza with a voltmeter.
assuming it's 12V this is a circuit i would need for my oxygen sensor http://acm-csuf.org/yuras/hho/oxygensensor.png
As long as I know, if a signal line shows 450mV, it's running normal (not too reach not too lean), therefore, i can trick ecu in showing that i'm running reacher then i am (while hho is injected).

[Über STi]

The O2S uses a 5v reference from the ECM. It returns a signal from about 100mV to as high as 1.1ish volts. Tricking the ecm through the O2S is not really effective, due to the nature of the signal and the overall fueling strategies. More effective is altering the MAF sensor, so that the ECM thinks less air is coming into the engine. Less air needs less fuel. That's why changing to larger fuel injectors requires a tune, as the ECM "fires" the injector for a given time based upon the amount of air expected/sensed by the MAF sensor and air temps (for density). The ECM would fire the larger injector for the same amount of time that it would fire a smaller injector, but the it would try and correct the amount of fuel based upon the O2S reading rich. Anyway, I know that there MAF-diddlers out there, like MAFiA and TwEECer(for FORDs).

[Ultra]

Thanx a lot. Your solution looks better. Wiki says that it outputs 0 to 5 volts proportionally. so dropping the voltage would help, but potentiometer is still not a good idea, because voltage drop is not linear.
I'm a Computer Science student, so the solution that I see is getting the performance data (@ constant hho gas flow find optimal voltage drop @ given signal value input), and then use micro controller together with DCP (digitally controlled potentiometer) to automatically adjust voltage drop. But this is not an easy solution. So I'm up for ideas =)
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Another thing that came up is where to inject HHO? Most of the guides say that the best place is ether right at the MAF sensor or right next to the carburetor. What would be your suggestions?

[BlackParis]

I dont get it? is your 1.8 turbod?

there is no reason to have water injection, unless you have done something crazy to the car, that would require cooler cylinders temps...

IF* you absolutely must have it THEN
my recomendation is to get a standalone ECU (microsquirt) get the car running with that (or a similar standalone), and as long as you chose one that can control/compensate for NOS or hho injection your set to move on to the hho injection....


I guess if your too cheap for that, you can get a different adjustable fuel pressure regulator, and turn down the fuel pressure so you inject less fuel...

Also look into a SAFC-2 or similar, if you are interested in "tricking" the maf... I know they trick it to work with turbos (more ait), but not sure about tricking it for LESS air...

[BlackParis]

I thought I should add some quotes from Wikipedia....



Fuel economy (http://en.wikipedia.org/wiki/Fuel_economy) can be improved with water injection, although the effect on most engines with no other modification, like leaning out the mixture, appears to be rather limited or even negligible in some cases.
Some degree of control over the water injection is important. It needs to be injected only when the engine is heavily loaded and the throttle is wide open. Otherwise injecting water may simply drown the engine and cause it to quit.




LOL this one is funny....

Use in automobiles

A limited number of road vehicles with large-displacement engines from manufacturers such as Chrysler (http://en.wikipedia.org/wiki/Chrysler) have included water injection. Saab (http://en.wikipedia.org/wiki/Saab) offered water injection for the Saab 99 (http://en.wikipedia.org/wiki/Saab_99) Turbo. With the introduction of the intercooler (http://en.wikipedia.org/wiki/Intercooler) the interest in water injection disappeared, but today, water injection is also of interest because it can potentially decrease nitrogen oxide (NOx) (http://en.wikipedia.org/wiki/Nitrogen_oxide) emissions in exhaust (http://en.wikipedia.org/wiki/Exhaust). The most common use of water injection in automobiles today is racing, particularly drag racing (http://en.wikipedia.org/wiki/Drag_racing) and illegal street racing (http://en.wikipedia.org/wiki/Street_racing).



ROFLS.. r u illegal streetracing?


Types of racing encountered on the street

Drag Racing (http://en.wikipedia.org/wiki/Drag_Racing) is a race which involves two or more competitors who drive in a straight line for a specified distance (usually a 1/4 mile). The driver that covers the most distance between the two cars or reaches the end first is the winner. Fundamental skills in drag racing are the ability to launch with minimal wheelspin (http://en.wikipedia.org/wiki/Wheelspin) and quick shifting skills. Reaching the engine's redline (http://en.wikipedia.org/wiki/Redline) happens in almost every race to get the full power out of the car's engine, but depending on the types of cars racing, the shift points may vary, as certain engines do not achieve full power at that point. This imposes the risk of critical engine damage if a redline misshift occurs.
A more common form of racing, in which two or more cars compete until one party is the clear winner. This differs from the above mentioned drag race, in which a set distance on a straight road is traversed. Drivers typically line up while moving under the posted speed limit. Once all the cars are ready, one car will sound its horn three times; the third time is the final signal to start the run. A car simply outruns the other vehicles by a considerable margin in order to win. If the winner cannot be determined, it is usually decided upon a mutual agreement, or having another race. Another way to signal a race is by flashing the vehicle's high-beams. This is typically run by high horsepower cars.

[Ultra]

BlackParis (http://www.dirtyimpreza.com/forums/member.php?u=336), I'm not talking about water injection. HHO is not quite water.
The idea is to use unused power (generated by alternator) to break down electrolyte (80%H20 + 3-4 spoons of NaHCO3 + and 20% of CH3–CO–CH3) to increase gas millage.
Electrolyte breaks down into combustible HHO gas that is injected together with fuel.
I've seen people reporting, like, 60 mpg with POS Ford engines, so i wanna check it out. =)

[Über STi]

One other thing that I thought of this morning re: O2S and tuning:
The O2S in MOST modern cars are "narrow band" sensors. Essentially, they tell the ECM that the A/F is lean or rich, but not by how much. In order to tune the A/F through an O2S, you must utilize a "wide band" sensor. These provide a more accurate, constant signal rather that the RICH-LEAN-RICH-LEAN-RICH-LEAN signal that the narrow band sensor generates. This also means that you need an ECM to interpret that wide band sensor signal. Good Luck. Please report back any successes or failures for the general knowledge-base of the community.

Originally Posted by BlackParis

IF* you absolutely must have it THEN
my recomendation is to get a standalone ECU (microsquirt) get the car running with that (or a similar standalone), and as long as you chose one that can control/compensate for NOS or hho injection your set to move on to the hho injection....
+1
The MS community has a lot of tuning experience and are willing to share.

[BlackParis]

BlackParis (http://www.dirtyimpreza.com/forums/member.php?u=336), I'm not talking about water injection. HHO is not quite water.
The idea is to use unused power (generated by alternator) to break down electrolyte (80%H20 + 3-4 spoons of NaHCO3 + and 20% of CH3–CO–CH3) to increase gas millage.
Electrolyte breaks down into combustible HHO gas that is injected together with fuel.
I've seen people reporting, like, 60 mpg with POS Ford engines, so i wanna check it out. =)


ahh.. lol.. well for getting rid of the fuel I would definitly use a MS... good thing about that is it can dual-map, so if you run out of electrolyte solution, then the engine will still run under a normal petrol only map...


I'll shut up now.. and just check back now and then to see what you do :D sounds interesting...

[my01rs-t]

MS FTW. I have never heard of what your trying to do but I would recommend MS for it.

[williaty]

You won't be able to alter fuel economy via the MAF sensor (and therefore by piggybacks like the SAFC). Since the car will spend most of its time in Closed Loop, the ECU with alter the fueling to hit stoich if you screw with the MAF input. You would need to be able to re-flash the ECU with a front 02 sensor scaling that alters the voltage the ECU interprets as stoich.

I suppose it would be possible to create a voltage divider on the front 02 signal, but I'm not sure if the car would then run richer or leaner.

Also consider that any alteration of the O2 sensor signal or O2 sensor scaling will change the entire tune of the car. If you lean the car out via either of those methods at crusie, you'll be running the same amount lean at WOT. You'd need to either be able to alter the Primary OL fueling table, or use a piggyback to increase the WOT fueling.

If you do use a piggyback, I recommend something like the eManage Ultimate which has the ability to increase fueling without changing the MAF signal since the MAF signal also affects timing, CL->OL Transition, and a bunch of other stuff.

[Ultra]

Thanx a lot.
I'm going to use a simple approach so far, just to see if it would work. I 'm going to alter the output voltage to ecu from O2 sensor. If this would show at least a little increase in MPG (I should be able to tune it to work at certain rpm efficiently (i hope)), I'm thinking of programming a microcontroller to do all the adjustments based on rpm.

[williaty]

Thanx a lot.
I'm going to use a simple approach so far, just to see if it would work. I 'm going to alter the output voltage to ecu from O2 sensor. If this would show at least a little increase in MPG (I should be able to tune it to work at certain rpm efficiently (i hope)), I'm thinking of programming a microcontroller to do all the adjustments based on rpm.
Just remember that doing it that way will cause you to run lean everywhere, including WOT, which can be dangerous.

[Jiggy jimmy]

Hi everyone.
I'm driving 1995 Impreza Outback Limited Edition, with 1.8 engine and stick shift =).
I've seen a lot about hho modification to the vehicle, and I wanna try to do it myself. But i Might need some of ur help here. =) After doing each of the steps, i'm going to blog it here with my results.
---
1st question. One thing that is very recommended is to trick your oxygen sensor. What voltage does it run of? I want to wire a potentiometer in the signal line, to trick ECU, so it will inject less fuel.

THANX

Just look at places like Eagle research.com, and Fuel-saver.org they will get you on the right path and fairly cheaply. Look up one electrolyzer called the Smack Booster it is non patented DIY instructions for building your own. Fuel saver.org has fairly simple instructions and procedures in tuning for milage to get around your MAF sensor. But mostly get informed Water4 gas is like a data base with ebooks for better mileage. Good luck this is enough to get you started !

Jiggy jimmy

[williaty]

Keep in mind that if you do anything to screw with your MAF sensor to try to get the car to run leaner, 2 things will happen:

1) The ECU will notice the lean condition and learn to add fueling in order to maintain stoich AFR
2) While the AFR sensor is inactive, the car will be under-estimating the amount of air entering the engine. This will cause it to run lean AT THE SAME TIME AS IT ADDS MORE TIMING. Both of those changes will increase the likelyhood and severity of knock, which is not a good thing for your engine's continued existence.


If, conversely, you actually meant you were going to alter the signal from the O2 sensor, the picture is a little different:
1) You will have to alter the signal from the rear O2 sensor in the same proportion. If the ECU sees the rear O2 giving strange data as compared to the front O2 sensor, it will make the car run rich to protect the cats and may also set a CEL.
2) You will need to alter your MAF scaling by the same amount and in the same direction to prevent the ECU from learning to severely lean out the AFR (which is dangerous in Open Loop)
3) You will need to alter your Open Loop fueling targets by the same proportion you altered your O2 scaling and MAF scaling to make sure you hit proper AFR at WOT rather than running dangerously lean. This will REQUIRE a wide-band O2 sensor.



In other words, there's none of this you can safely do without specific custom tuning.