1987 voyager with displacement on demand...

[Ondonti]

Quote:

Originally Posted by 87GLHS465 sounds like someone needs to learn how an O2 sensor works

Yes what I said is wrong.

It would help if a wideband was being used to see what the real a/f ratio is when only 3 cylinders are being run on......and compare that to what happens if you also cut o2 sensor feedback to the ECU.

Not a great idea to run 3 cylinders way to rich if that is actually happening.
With certain wideband sensors you could actually send a false signal that will not show how lean things really are so maybe you could not only run on 3 cylinders, but have the a/f ratio up around 16-17:1 when cruising.

[lookin]

If you cut o2 sensor feedback it wouldn't be wideband anymore though would it?

I think running on just 3 cylinders may also trash the wrist pins and plane bearings all around eventually.

[c2xejk]

Quote:

Originally Posted by lookin If you cut o2 sensor feedback it wouldn't be wideband anymore though would it?

The "false" signal is modified version of the "true" signal. So you could offset the signal rich or lean...

I would need to dig through my stuff. A while back I designed a circuit to make the O2 look leaner (so extra fuel would be added.) I have to see if it would work in reverse (ie. Make the O2 signal look richer so the ECU doesn't add extra fuel.)

[nolydi86conques]

sweet can u tell me how to wire it

[lookin]

Quote:

Originally Posted by c2xejk The "false" signal is modified version of the "true" signal. So you could offset the signal rich or lean... I would need to dig through my stuff. A while back I designed a circuit to make the O2 look leaner (so extra fuel would be added.) I have to see if it would work in reverse (ie. Make the O2 signal look richer so the ECU doesn't add extra fuel.)

Great idea.

All you would need to lower the signal, thus leaning the mixture, is two tiny resistors in series, and you could make it variable [tunable] by adding a small variable resistor [pot]. Total cost of components would be roughly one dollar.

To raise or lower the output signal, for a tunable richening or leaning of the mixture, you would need a tiny instrumentation amplifier about the size of a nickle, with a variable resistor [pot] the size of an aspirin or smaller. The total cost of components would be roughly one hundred dollars.

[ShelbyDodgeImp]

Quote:

Originally Posted by lookin Great idea. All you would need to lower the signal, thus leaning the mixture, is two tiny resistors in series, and you could make it variable [tunable] by adding a small variable resistor [pot]. Total cost of components would be roughly one dollar. To raise or lower the output signal, for a tunable richening or leaning of the mixture, you would need a tiny instrumentation amplifier about the size of a nickle, with a variable resistor [pot] the size of an aspirin or smaller. The total cost of components would be roughly one hundred dollars.

You could probably do it for less than that, but there would be few applications for the circuit given that the O2 is ignored at times (WOT for instance) at which points its signaloutput won't matter a bit. That and, you can only adjust the A/F mixture so much using modified O2 readings.

Now if you had an adjustable fuel regulator on the rail that you could control electronically... I know not all are vac based.

[the machine]

fuel is used to lubricate the valve edge and the valve seat, it also gets on the shaft of the valve and then goes up into the vave guide, look at a can of starting fluid, most newer ones have "top end lubricants", and lucas oils has top end lubricant fuel additives you can add to you fuel tank just like injector cleaner, just the same way lead was used to soften the bang on the valve seats in older motors, after a good amount of miles there will be a noticeable difference in the engines compression on that bank,

Quote:

Originally Posted by Ondonti Not understanding valve seat/guide wear or ring wear. Plug fouling yes. The others dont sound plausible at all. Lets hear the reasons. Combustion has nothing to do with valve guides or valve seats (except that the exaust valve seat removes heat from the exhaust valve which doesnt matter when the cylinder is not firing). Lack of combustion pressure will mean the rings are not pressing against the cylinder walls with any pressure except innate ring tension that already pushes against the cylinder walls. Cylinder glazing is a problem that can happen in a poorly broken in engine but in an engine that already has decent ring seal I dont think this would happen.

[lookin]

What was that Robert Palmer song? Gonna have to face it we still need a CAL? Something like that. My recollection may be influenced by current concerns though.

[sgt. minivan]

so basically if i dont have several spare engines laying around, then this is usless lol, i dont want to damage my engine, i just had a brain wave one day and thought of it, i also thought of wiring up 2 switches(like machine mentioned) so that i can switch between 2 4 6 and 1 3 5 to not ware out things... but i never got around to going that, once again when i go home in 3 days il take a video of it running + no making fun of my van lol..... i was 15 when i started "modding" it... and its been over 3 years since i could put any more time in it.

[Ondonti]

Quote:

Originally Posted by the machine fuel is used to lubricate the valve edge and the valve seat, it also gets on the shaft of the valve and then goes up into the vave guide, look at a can of starting fluid, most newer ones have "top end lubricants", and lucas oils has top end lubricant fuel additives you can add to you fuel tank just like injector cleaner, just the same way lead was used to soften the bang on the valve seats in older motors, after a good amount of miles there will be a noticeable difference in the engines compression on that bank,

Like I said, alchohol cars have no lubrication from fuel.
Valve edges and seats have no reason to be lubricated.

Your valve stems are lubricated by oil that goes past the valve stem seal.

If you didnt have oil in the valve guide your valves would wear out in short order. Thats why some valve guides are actually grooved to help oil have space to get into the valve guide to help lubricate the valve stem.

The exaust valve is under huge amounts of stress compared to the intake valve and liquid fuel never comes in contact with the exhaust valve guide or seats. The intake valve has a walk in the park compared to what the exhaust valve is expected to do.
Doesnt really matter what some product for sale says about top end lubricants.

[nolydi86conques]

ok

[c2xejk]

Quote:

Originally Posted by lookin Great idea. All you would need to lower the signal, thus leaning the mixture, is two tiny resistors in series, and you could make it variable [tunable] by adding a small variable resistor [pot]. Total cost of components would be roughly one dollar. To raise or lower the output signal, for a tunable richening or leaning of the mixture, you would need a tiny instrumentation amplifier about the size of a nickle, with a variable resistor [pot] the size of an aspirin or smaller. The total cost of components would be roughly one hundred dollars.

The problem is, the O2 sensor can only source so much current. So if you use a resistor divider network, you increase the amount of current the O2 sensor must source...

The circuit I used does not have this problem. It uses some amplifiers to buffer the input and output. It was designed by a systems engineer friend of mine who designs this kind of thing for a living... Yes it uses an pot so it is adjustable.

Also to lean out the engine, you want to make the ECU think that it is richer. Thus you want to _raise_ the voltage signal...

[lookin]

Quote:

Originally Posted by c2xejk The problem is, the O2 sensor can only source so much current. So if you use a resistor divider network, you increase the amount of current the O2 sensor must source...

What are you talking about? I said nothing about a "resistor divider network". I also said nothing about, putting the resistors in series parallel, which may be what you refer to.

The circuit I described in part one, does not have the problem you speak of, because series resistance can only decrease the current, and therefore there could be only less current load on the 02 sensor.

Quote:

Originally Posted by c2xejk The circuit I used does not have this problem. It uses some amplifiers to buffer the input and output. It was designed by a systems engineer friend of mine who designs this kind of thing for a living... Yes it uses an pot so it is adjustable.

Exactly what I described in part two. It is my best friend's idea, who is an electronic engineer. She designs and makes IC boards at home as a hobby.

Quote:

Originally Posted by c2xejk Also to lean out the engine, you want to make the ECU think that it is richer. Thus you want to _raise_ the voltage signal...

Yeah I get that Ed. I mixed up my terms is all.

[lookin]

Here is what I meant.

All you would need to lower the signal, thus richening the mixture, are two tiny resistors in series, and you could make it variable [tunable] by adding a small variable resistor [pot]. Total cost of components would be roughly $1.00 is all.


To raise or lower the output signal, for a tunable leaning or richening of the A/F mixture, you would need a tiny instrumentation amplifier about the size of a nickle, with a variable resistor [pot] the size of an aspirin or smaller. The total cost of components, would be roughly $100.00 for a good reliable tunable circuit that could easily withstand vibrations, weather and engine bay temperatures.

[c2xejk]

Quote:

Originally Posted by lookin To raise or lower the output signal, for a tunable leaning or richening of the A/F mixture, you would need a tiny instrumentation amplifier about the size of a nickle, with a variable resistor [pot] the size of an aspirin or smaller. The total cost of components, would be roughly $100.00 for a good reliable tunable circuit that could easily withstand vibrations, weather and engine bay temperatures.

Having built one out of automotive grade components for some testing, I can definitively say it would _NOT_ cost $100.... Even in small quantity, the parts were more like $20-30... The op amp chip I used was smaller than a dime... Probably fit 2-4 on a dime...

The resistors in series would only lower the sensed voltage which would make the ECU think the engine was slightly leaner. That would result in adding more fuel... That is the opposite of the goal in this case...