How do i lean back the fuel?

[Skunksmash]

Is there a way to manually lean back the fuel on a TBI engine? Specifically an '87 5.7 liter TBI engine. I know that the O2 sensor detects the ammount of oxygen and adjusts the fuel accordingly, but i am looking for a manual way to lean the fuel back as far as i can. Is there some screw or something somewhere on the TBI unit much like on the carbs that came before it?

[VileZambonie]

Why would you want to do that? Are you hoping to burn a valve or ruin your engine?

[eventhorizon66]

Trust in your ECU to deliver the best A/F ratio, unless something is wrong and it's not running right.  Are you hoping to do this as a fuel saving measure?  Or is it running pig rich and fouling plugs?

[Unofficial]

No offense, but if you're willing to risk ruining your engine by forcing it to run lean to save gas, you're better off driving something with better fuel economy to start with.

[Skunksmash]

No. I just need a way to lean it back so that when i am ready, i can install my HHO generator on the truck. Unless you lean back the fuel on any vehicle using an HHO generator, you will gain nothing. The idea is to supplement the gasoline with hydroxy gas, and you cant do that while spraying as much gasoline as you always used to. Not only that, if it can (which is almost always) the 02 sensor will detect that extra oxygen and the computer will then increase the fuel being sprayed. Which of course is counter productive. This is kinda also the reason i had the gas mileage thread. I thought maybe if i could squeeze out a few more MPG out the engine normally and without the generator, then the results with the generator on the truck would be maximized. A friend of mine uses an HHO generator and achieves 59 MPG highway in his Geo. Now granted thats a 4 banger, but it was never meant to do that well. So i figure even these old trucks would see a good increase in MPG. Might be able to get it up to around 25-30MPG. It's only around $100 to build the generator so it would completely pay for itself in about 2 tanks of gas. Every day after that is just savings.

[Captkaos]

What kind of Geo?  The Geo Metro in 1989 was a 3 cylinder that was Rated for 51MPG on the 43MPG in the city.  It WAS designed for high mileage like all the other Geo's.

[Skunksmash]

Oh no lol, this car could never get even close to that without a generator. Its a newer geo tracker, but im not sure as to the exact year. I will have to ask him that. So uh, anyone know how to lean out the fuel on a TBI?

[TexasRed]

You might be better off trying to use megasquirt.

[Skunksmash]

Or a carburetor.

[TexasRed]

That would be the easiest way.

[FlatBroke]

Hang on Skunksmash....Let me see if I can e-mail you a link from another site.....

Be right back.

[FlatBroke]

http://mileagemaker.us/efieplans.pdf


Se if that thing looks like it will accomplish what you want to do. Let me know if I can be any further help.

[eventhorizon66]

Or a carburetor.

Let me get this straight, you want to go from TBI to carb to improve fuel efficiency.  This ought to be good.  Keep us posted on how it works out.

[zieg85]

I would like to see what this is all about.  I ran my 4.3L last night (push started it) carb is in excellent shape which I will put on my 350 when I transplant it and try this ad.  I am planning on looking at this setup hard just to be different.

[VileZambonie]

oh boy.