Fooling the ECU to burn lean...

[klrv6]

Originally Posted by justpassntime

It is so much easier if your car has a atmospheric or barometric pressure sensor.

This sensor, depending on what your particular manufacturer calls it, controls the fuel mixture by sensing the ambient pressure at what ever altitude you are driving. The higher the altitude the leaner the fuel mixture.

All you do is put a 25k potentiometer switch on it and turn it down till the idle speed changes. All you are doing is telling the ECU you are driving at a higher altitude than you really are. There are no problems with warning lights or ecu problems this way.

Just be cautious you don't do to far or you can burn pistons or valves due to higher cylinder temperatures.

I was thinking the same thing. Until you can go into the ecu and tell it what afr to run at, just lie to it about the load it's under. It will go to another *lighter* part of the fuel map and put in less fuel. Just be careful...

[metromizer]

I think a guy could be plenty careful if he used stand alone Exhaust Gas Temp (EGT) monitoring and data logging. It's the most 'real time' combustion temp sensing I know about.

But if pepole have tried it and had no better FE as a result, why bother?

[justpassntime]

Originally Posted by computerpc101

I have an old 89 Civic Wagon 5 sp, I would like to modify it and run it slightly lean. I have 3 pin PA sensor, One end/centre pin measure about 3K, other end/centre pin measure about 5K, Would you tell me more about how that how I connect those potentiometer?

Thanks

All I know to tell you is that one of the wires is 12v one of the other wires is somewhere around 2.75-3v. You want the lower voltage one. The other wire is the ground. You will have to use a volt meter to check them out. Remember to turn the key on or you may be scratching your head for awhile.

[computerpc101]

Thanks justpassntime:

I will spend little more time to find those wires and measure and see that it will work or not.

I know nothing, I may be wrong, I think that If car at high atmospheric, Air contains less Oxygen, So ECU picks up this condition and reduce fuels and it causes slightly lean burn.

I will let you know It works for me or not.

Thanks anyway

[computerpc101]

Originally Posted by klrv6

I was thinking the same thing. Until you can go into the ecu and tell it what afr to run at, just lie to it about the load it's under. It will go to another *lighter* part of the fuel map and put in less fuel. Just be careful...

For my car, 1.5L 89 Honda Civic wagon, I saw a sample of Fuel map of my car, It seems that we can fool ECU to think that " Lighter load" by offset MAP sensor resistor value by resistor. It will offset fuel map easily too.

Of course, If we can change ECU fuel map easily, It is a better choice, We can fine tune is for best fuel map for fuel economy VS power.

Both Map or Atmospheric sesor mod are dirt cheap, below $1, ECU fuel map modify cost more money and it needs time to learn this editing program, That fuel map.... better but a lots harder...

[computerpc101]

Well, I find that SuperMid, It looks like that it is hard to get it and not cheap, and my car only worth few hundred dollars.....

From my understanding, SuperMid is using a ATmel Micro controller to check car sensors for speed, Amp, enginee speed, Fuel injector duration Vs Speed for fuel consumtion, SuperMid is designed really for Hybrid car....

[modmonster]

diesel john

i like your idea about the battery voltage divider circuit for adding series voltage to sensors. it has given me ideas.

according to wiki, lean burn is beneficial because it reduces losses due to throttling the air and instead replaces this speed control method by leaning out the fuel. so for ideal efficiency you want to operate at WOT and control engine speed buy changing the air/fuel mixture.

we could use a variable resistor on the MAF sensor. opperation would be normal under closed loop control where lambda sensor "is god". at WOT, open loop control, the MAF is used and a variable resistor here would allow us to control the mixture.

my MAF is broken. it has lost calibration and the voltage is way too low so i am getting lack of power at WOT, too lean and the engine stalls. i am going to put a battery with voltage divider circuit in series with my broken MAF to try this same principle.

[basslover911]

Lean burn, lean burn, lean burn...

Why havent yall thought about controlling the EGR valve instead? Or placing a second one to increase the flow during low load operations... ?

It practically does the same thing as lean burn, but more safely, does not increase emissions (actually decreases it), acts as a WAI, etc etc etc.

Don't get me wrong, I have thought about doing lean burn, but its not that simple since the engine has so many variables into controlling AFR. Instead, just keep it at 14.7 but add less oxygen (exhaust), AND it also keeps the CAT happy.

Thoughts? I am about to go either route, but I am seriously thinking more and more about doing more EGR (mainly because of reduced emissions)

[cfg83]

basslover911 -

Originally Posted by basslover911

Lean burn, lean burn, lean burn...

Why havent yall thought about controlling the EGR valve instead? Or placing a second one to increase the flow during low load operations... ?

It practically does the same thing as lean burn, but more safely, does not increase emissions (actually decreases it), acts as a WAI, etc etc etc.

Don't get me wrong, I have thought about doing lean burn, but its not that simple since the engine has so many variables into controlling AFR. Instead, just keep it at 14.7 but add less oxygen (exhaust), AND it also keeps the CAT happy.

Thoughts? I am about to go either route, but I am seriously thinking more and more about doing more EGR (mainly because of reduced emissions)

This is a cool idea. Different/bigger/multiple EGRs? I hadn't heard this before. What are the issues in implementation?

CarloSW2

[basslover911]

Originally Posted by cfg83

basslover911 -



This is a cool idea. Different/bigger/multiple EGRs? I hadn't heard this before. What are the issues in implementation?

CarloSW2

I really don't think any. Heck if you inject more than necessary exhaust gas I think the worst that could happen would be a slight overheating and the engine dying (since there is no oxygen to burn) This, however, would not destroy the engine- start it back up and your set.

I would think injecting it into the air intake tube instead of inside the intake manifold would be best. That way you also open up more the throttle due to the denser air (hotter exhaust gas temperature) and decrease throttle losses- another advantage that Lean burn doesn't necessarily give you.