Learn how your fuel trims work

[Olympiadis]

here:
http://www.gnttype.org/techarea/faq/BLMINT.html

[myoldyourgold]

The chart on this site shows that at idle 0 adj is made. That is not what I see on my scan gauge. When I add HHO at idle the mixture goes rich to compensate for the load on the alternator and to maintain proper idle. When you inject a very small amount this might not show up. I will have to test this when I have time and see how much load/amp draw there has to be before it shows up.

[Olympiadis]

The chart on this site shows that at idle 0 adj is made.

I don't see that, not at the link I posted. It shows that you are in load cell number 0 at idle, but yes fuel trims are absolutely made at idle. Zero is just the name of the load cell, not the fuel trim value.

What it does say is: "Since the RPM is very low and the MAF is very low, the car will be using the information in BLM Cell 0 to adjust the idle fuel mixture. The value contained in that cell is adjusted with the Integrator values (which change based on O2 readings, etc.)."

Both the load cell boundaries (qualifiers), and the upper and lower range of fuel trims can be re-defined by the tuner by changing the calibration in the chip.

Since HHO is 88% O2 by weight, the ECM is naturally going to increase the fuel trim at idle based on feedback from the O2 sensor.
If you are injecting post-throttle-valve, then your idle speed may also go up due to the IAC no longer being able to lower idle back to the commanded speed.

If you're trying to lower the idle speed (and you probably should be), then keep in mind that the minimum air-rate, or throttle valve adjustment ( the physical throttle-stop screw ) controls the minimum idle speed allowable even with the IAC counts at zero (IAC fully closed). Also keep in mind that the PCV valve and any other vacuum leak will also be a source of idle air when the IAC is fully closed. PCV contains less oxygen than normal air, and it also contains volatiles. The PCV system is also vented to outside air, so if the engine is pulling more air flow through the valve than crankcase vapor being produced, then it pulls more fresh outside air into the system via the vent. That will also be an extra source of O2 during idle that doesn't necessarily need to be there.

I'm not saying that having surplus O2 is necessarily bad, because I don't think it is, but you have to have complete control over the adaptive fueling logic to keep the fuel consumption down. Otherwise you're continually fighting the system.

If you control the fueling logic via the ECM, then you also have control of a great many other things that you can use to lower fuel consumption. For instance the IAC throttle follower logic adds to fuel consumption while you are coasting by increasing the idle speed at that time. The logic is there for smoother driving, but it costs a lot of fuel if you do a lot of coasting with the engine running. There are other similar algorithms that should be addressed but all require control over the ECM.

[myoldyourgold]

Since HHO is 88% O2 by weight, the ECM is naturally going to increase the fuel trim at idle based on feedback from the O2 sensor.

Also keep in mind that the PCV valve and any other vacuum leak will also be a source of idle air when the IAC is fully closed. PCV contains less oxygen than normal air, and it also contains volatiles. The PCV system is also vented to outside air, so if the engine is pulling more air flow through the valve than crankcase vapor being produced, then it pulls more fresh outside air into the system via the vent. That will also be an extra source of O2 during idle that doesn't necessarily need to be there.


If I understand you correctly the only place the extra O2 can come form is through the PCV circuit. Unless you are saying that the perfect mixture of HHO does not totally get consumed. If that is the case I must disagree. At idle my reactor is off and not producing HHO so no problems at idle. Look at it this way all the HHO you put in is consumed, now what is left is fuel, air and some oil vapor through the PCV. The total mixture gets almost all consumed. So the only place the extra O2 comes from is only through the PCV system based on your explanation and my understanding. It is not from the HHO or you would have excess H in the exhaust and there is none. It looks like the only explanation is the PCV system based on what you said. Very interesting. You are welcome to correct me if you think I am wrong. This is why I am able to fool the ECM with controlling the PCV and EGR with no electronics but is way more complicated requiring more skill to tune things.

[Madsceintist]

Man I don't have the time needed for this .........

The PCV system SHOULD be restricted to internal air not outside fresh air. Most systems use the small amount of blow-by from the cylinders and air that's already entered the throttle chamber through the filter. The pcv valve pulls the crankcase air(blow-by gases, small particles of oil that are thrown around to become air-born, and the filtered air) from the throttle area(usually in the air duct or resonators) into the intake where there's a constant vacuum. Limiting this system could cause and will cause leaks in an engine that has worn cylinders that have considerable blow-by. If you have the need or want to eliminate the O2 from the pcv system you can cancel it all together. However you lose the small amount of oil that gets through(honestly not important). Cap off the intake side of the vacuum and install a small filter(tiny k&n style) on the feed side. This leaves the crankcase to breath but keeps out trash.

All of this about the PCV is moot as it all depends on the engines wear and the cleanliness of the system and valve size. Eliminating it's the only way to truly control what COULD possibly get through. IT does make a HUGE difference on how clean the IAC or ICM stays! The only reason these get dirty is due to the dirty oil and carbon deposits!

[myoldyourgold]

Madsceintist, no one is talking about eliminating the pcv system but if you study what the pulsing motion does you would understand that there is a much better way. There are approved separate trap/filter systems that are available that are much more effective and can be tuned to get the best performance out of the engine. Most are made for race engines but are some are street legal. What the discussion is about is where the extra O2 comes from and how to deal with it.

Now if you want to discusses crankcase pressure and how to deal with it that is a different discussion. Some very interesting things there too, that when done right help HHO.

[Olympiadis]

If I understand you correctly the only place the extra O2 can come form is through the PCV circuit. Unless you are saying that the perfect mixture of HHO does not totally get consumed. If that is the case I must disagree. At idle my reactor is off and not producing HHO so no problems at idle. Look at it this way all the HHO you put in is consumed, now what is left is fuel, air and some oil vapor through the PCV. The total mixture gets almost all consumed. So the only place the extra O2 comes from is only through the PCV system based on your explanation and my understanding. It is not from the HHO or you would have excess H in the exhaust and there is none. It looks like the only explanation is the PCV system based on what you said. Very interesting. You are welcome to correct me if you think I am wrong. This is why I am able to fool the ECM with controlling the PCV and EGR with no electronics but is way more complicated requiring more skill to tune things.

An engine running at stoich does exhaust HC and O2, and an especially high percentage of both at idle speed due to the very slow charge velocity in the ports. Part of the O2 from the PCV system is included in this wasted exhaust and part of the O2 from the HHO system is also included.
This is so because the engine cannot physically trap 100% of the charge in the chamber. Some of it escapes via the exhaust valve during the overlap period at the beginning of the intake stroke. The % of wasted charge becomes smaller as the RPM is increased, but it can be a problem at low RPM because the O2 sensor measures the wasted O2.
Some of the excess HC and O2 will burn in the pipe, and some will burn in the converter, but the O2 sensor will measure some of the O2.

As far as fuel trims go and the ECM maintaining stoich, the O2 sensor always has the final say on fueling.
From what I gather, many people have had trouble with fuel trims being added at idle and low RPM when their HHO systems are active.
I'm not at all surprised by this because the percentage of O2 going into the engine is being increased. The fact that it is in perfect proportion to H2 is really irrelevant. You can have perfect proportions of O2 and gasoline going into the engine and still get unburned HC and O2 in the exhaust.
The average of 0.450 volts from the O2 sensor during stoich operation does not represent zero O2 in the exhaust. There is still O2 in the exhaust with a measured AFR of 14.6:1.
A richer mixture (less relative O2) produces a higher average voltage from the O2 sensor. This is because there is a larger difference between atmospheric O2 and the O2 inside the exhaust pipe. I have tuned some vehicles that started out running so rich that they over-pegged the O2 sensor at 1.2 volts. That represents very little O2 present, but not absolutely zero.

Also keep in mind that the O2 sensor (wide or narrow band) is only measuring the byproduct in the pipe, and does not accurately represent what is happening in the combustion chamber. The amount of early and late burning before and after TDC can vary greatly and still result in the same measurement in the exhaust pipe.
By the same token you can keep fuel delivery (injector pulse-width) steady, but change the spark advance and see a difference in AFR as measured in the pipe, even though the amount of air & fuel have not changed.

I'm not sure why the explanation of PCV operation popped up, but madscientist is correct. Very high mileage engines sometimes require two PCV valves, and/or multiple vents to control the crankcase pressure and avoid blowing out gaskets/seals. It is also possible to eliminate the PCV valve and the feed into the intake manifold by adding the required vents.
It is also possible and often desirable to filter the PCV flow into the intake manifold.

The combination of tacky PCV vapor and soot from the EGR combine to make a real mess inside the engine. I recondition cylinder heads so I see the results of these emissions devices all the time. Because of this I always filter my PCV flow into the intake.

If you're trying to create a very low and stable idle speed, then it may be advantageous with some induction systems to delete the PCV flow at idle.

I would not have an HHO feed line set up so that the PCV draws the HHO into the crankcase. If the HHO is going into the air duct before the throttle valve, then I think it best to use an external vent for the PCV as madscientist suggests. Just add a small clear fuel filter to the end of the vent line.

myoldyourgold, why did you decide not to run the HHO while at idle? Is it because of the amperage draw?
If so then you might consider killing the alternator when at idle.

Here's a pic of an engine that was taken out of service because of overheating. The port that feed the EGR blew past the gasket and filled the engine with exhaust soot.
The next is a pic of a high mile engine requiring two PCV valves and two PCV vents. There was no HHO system involved.

http://i702.photobucket.com/albums/ww27/olympiadis3/1991%20Chevy%20C1500%20pickup%20truck%20project/Intake%20manifold%20modification%20and%20re-sealing/EGRleak.jpg
http://i702.photobucket.com/albums/ww27/olympiadis3/1991%20Chevy%20C1500%20pickup%20truck%20project/Intake%20manifold%20modification%20and%20re-sealing/EGRleak.jpg

http://i702.photobucket.com/albums/ww27/olympiadis3/1991%20Chevy%20C1500%20pickup%20truck%20project/Oil-pan%20replacement%20and%20oil-pump%20rebuild/DSCF5917c.jpg
http://i702.photobucket.com/albums/ww27/olympiadis3/1991%20Chevy%20C1500%20pickup%20truck%20project/Oil-pan%20replacement%20and%20oil-pump%20rebuild/DSCF5917c.jpg

[myoldyourgold]

Valve over lap has always been a problem with HHO. I have a very hard time believing that the small amount of HHO in relation to the total charge that we are injecting is causing the 02 sensor to sense more O2 with just the amount that escapes with the over lap. I do not see where any excess O2 will come from in a properly functioning PCV system either. I am also very confident that all the HH in HHO and all the O in the charge that does not escape in the valve overlap, is consumed leaving no excess O2 from the HHO. So unless the amount that escapes in the valve over lap is enough there should not be any excess O2 based on this discussion. I think we are missing the fact that the ratio of O2 to all other burnable substances in the exhaust is what has changed due to a faster more complete burn as a result of HHO. Not an increased volume of O2. Does that make any sense? The O2 sensor after all is comparing it with outside air which is mainly nitrogen. As we lean out the fuel more and add more HHO to compensate making a faster burn, having to retard the timing and still maintaining the HP there will be more and more 02 or less other junk in the exhaust. There also will be more HHO in the overlap escape just because there is more in the charge and if carried to extreme will actually burn in the header. One thing for sure is as HHO is increased the O2 sensor senses more O2. I am not sure we have a complete explanation yet.


myoldyourgold, why did you decide not to run the HHO while at idle? Is it because of the amperage draw?
If so then you might consider killing the alternator when at idle.

There is a number of reasons not to run HHO at idle. Amperage draw is one but it is not so much idle as load which does shut it down at idle. By this I mean when you take your foot off the accelerator slowing down rpm drops load and there is no need for HHO especially if you are running large amounts and using your engine as a brake going down large hills. You surly do not want a bunch of HHO being made while doing that or any time you take your foot off the throttle. Yes killing the alternator would also help and of course you can carry it further and kill the engine also like is done in some of the hybrids. As you pointed out the overlap is the most at idle and so you loose more of the HHO at idle and ratio of charge to HHO is much higher for no good reason upsetting the ECU even more. It also seams to help the ECU stay in a more favorable position. You are the expert in that field not me I just know what happens by doing it which is larger gains when done right and staying on the lean side. When you are pulling 40 to 100 amps in some cases it does make a difference. Of course I am talking about larger engines than a little 4 banger.

Some of the larger diesels are using well over 200 amps. The larger diesel engines are set up differently and the HHO is controlled by RPM/throttle position if they are on road varying RPM vehicles or larger engines (30 liters or bigger) on large generators are tuned for a very narrow RPM operating range. Most of these stationery engines have no electronic sensors to upset things and are slow RPM engines and really like HHO. The newer they are, things begin to change and electronic fuel injection will start making it more complicated but might result in better gains with good tuning.

[Madsceintist]

Well crap.

[Madsceintist]

Just to throw out there. Several of today's models i.e.; Ford, has a charging system that only "charges" on demand via the computer controls.

Has anyone played with a SUN gas analyzer ?

[Olympiadis]

No on the SUN equipment.
Our Focus alternator has a PCM controlled voltage regulator, and I really wish that it didn't.

[Madsceintist]

No on the SUN equipment.
Our Focus alternator has a PCM controlled voltage regulator, and I really wish that it didn't.



As far as the car without any extras that setup is fine. But you add a stereo system or anything that requires high loads then it sucks. I'm thinking of a use for that alt however for secondary power. Details later...........