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Discussion Starter · #1 ·
Instead of doing the wideband thing...I was planning on doing the odb2 scanner tool anyway, and I believe this charts a/f also. If this is hooked up regularly, it should be a good way to figure out what is going on, no?




FUNKIN INVALID_SESSION *These forums suck!*
 

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Discussion Starter · #2 ·
...of course, it'd be good to know the conversion from voltage to AF
 

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No, it wouldn't be a good way to know what your a/f is, because they are narrowband sensors, which, rather than ouput a linear voltage curve as a/f increases, they hold a steady voltage when below around 14.6:1, then "jump" to a second voltage for lean...

The resultant curve looks like:
.........................................0V
======\..........................0.2V
...............\.........................0.5V
................\==========..0.8V
..........................................1V
12 13 14.7 15 16 17

How do you tell the difference between 12:1 and 13:1? You can't.

Thus, it is worthless for telling you what your actual a/f is. That is what a "wideband" is for.
 

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If your O2 sensors are before the turbo they will be worthless (kind of) as soon as you hit positive manifold pressure. O2 sensors are very finicky and pressure changes can cause inaccurate reading. The best bet is to install a wideband 12-18" after the turbo in the downpipe and log that.

I thought the IS had 1 wideband though, otherwise how would it be able to hit the 12:1 afr (IIRC) at wide open throttle like it does stock.

p.s. Matt you may remember me, I'm one of the Suby guys from the Novi meet.

Seth
 

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mbiker97 said:
I thought the IS had 1 wideband though, otherwise how would it be able to hit the 12:1 afr (IIRC) at wide open throttle like it does stock.
Open loop.
 

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mbiker97 said:
I understand it's open loop but what dictates the fueling when it's in open loop. It's not the fuel map/maf reading only is it?
Yup. That is how piggybacks work- they modify the fuel map by taking MAF/TPS inputs and modifying the maf voltage to the ecu, when the car is in open loop, the result is that you can pretty much run whatever a/f you want if you determine the appropriate false maf sensor voltage to feed the ECU at a given rpm/maf/tps voltage.

Now do it for a bunch of points, and put it in tabular format. If you like, add a supplementary map sensor so you can continue to get readings if your maf sensor is capping out at 5V. Bam! You've just created the greddy emanage, S-afc, etc.
 

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doublins said:
Yup. That is how piggybacks work- they modify the fuel map by taking MAF/TPS inputs and modifying the maf voltage to the ecu, when the car is in open loop, the result is that you can pretty much run whatever a/f you want if you determine the appropriate false maf sensor voltage to feed the ECU at a given rpm/maf/tps voltage.

Now do it for a bunch of points, and put it in tabular format. If you like, add a supplementary map sensor so you can continue to get readings if your maf sensor is capping out at 5V. Bam! You've just created the greddy emanage, S-afc, etc.
with all these tech contributes.. why don't you have dots? Here.. you deserve some..
 

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rllinghardis300 said:
doublins said:
Yup. That is how piggybacks work- they modify the fuel map by taking MAF/TPS inputs and modifying the maf voltage to the ecu, when the car is in open loop, the result is that you can pretty much run whatever a/f you want if you determine the appropriate false maf sensor voltage to feed the ECU at a given rpm/maf/tps voltage.

Now do it for a bunch of points, and put it in tabular format. If you like, add a supplementary map sensor so you can continue to get readings if your maf sensor is capping out at 5V. Bam! You've just created the greddy emanage, S-afc, etc.
with all these tech contributes.. why don't you have dots? Here.. you deserve some..
I'm a moderator, and can have as many dots as I like... all I have to do is give them to myself or take them away. Likewise, I can take away anyone's dots. So can any other moderator. I had some dots, but someone *cough* thinks it's just hilarious to keep taking them away from me... Now, I know who it is, but I don't really care. If people want to be petty, then that's their perogative. I could really care less... I just keep on keeping on.

Thanks for the dots, though :wink: Here, have a present yourself
 

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doublins said:
Yup. That is how piggybacks work- they modify the fuel map by taking MAF/TPS inputs and modifying the maf voltage to the ecu, when the car is in open loop, the result is that you can pretty much run whatever a/f you want if you determine the appropriate false maf sensor voltage to feed the ECU at a given rpm/maf/tps voltage.

Now do it for a bunch of points, and put it in tabular format. If you like, add a supplementary map sensor so you can continue to get readings if your maf sensor is capping out at 5V. Bam! You've just created the greddy emanage, S-afc, etc.
WTF are you talking about?

wait
lemme ask you a second question.
WTF are you talking about?

-De
 

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SophieSleeps said:
I'm running open loop with an e-manage.
WTF are you talking about?

wait
lemme ask you a second question.
WTF are you talking about?

-De
:lol:

I was talking about how any piggyback (emanage included) works.

It basically allows you to "reprogram" the ecu's basemap to achieve whatever a/f you would like with whatever size injector (there are limitations in injector choice) when the car is in open loop. This is achieved by having the piggyback intercept the maf input.

The unit contains a 3d table with 2 independant variables (rpm, maf voltage) and one dependant variable (maf OUTput to ecu). Many piggybacks offer supplementary enrichment (meaning adding x millivolts to the maf output to ecu) by throttle position, or rate of change, or what have you.

Now, when the car is in closed-loop (idling, coasting, low-load accelleration) the ecu will NOT go strictly by this voltage that you give it. It will use information taken from the first o2 sensor to richen/lean out the a/f as necessary in an attempt to achieve a 14.7:1(stoic) a/f ratio. Even if you tell the car you want it to idle at 12:1, it will idle at 14.7:1 after running for a few minutes. This is hardly a problem, though, as you don't need to be running a 12:1 a/f ratio at idle, or under gentle acceleration.

"Limp" mode- If you try to get the car to run TOO rich under closed-loop conditions (primarily under vacuum, idle, coasting), it will not be able to correct (lean out) the a/f enough to achieve 14.7:1 under closed loop, and it will flip out, thinking something is wrong, going into the infamous "limp mode" This is something that your tuner should easily be able to avoid.

There are more secrets to tuning using a piggyback ecu, and I will tell you this- the car does not HAVE to run 14.7:1 under closed loop operation. In fact, I have been working closely with some associates such that I will soon have programmable closed-loop a/f using the stock ECU. Once r&d is finished for that, you too will be able to do it also. Not that it's THAT important to be able to do it, but it is extra security when running f/i. Howdya like them apples?

The best part about all of this? You maintain all of the stock functions of the ECU... trac, CELs, knock detection, automatic timing retard in the event of knock, closed-loop operation... Basically the stock ecu still does all of the work for you, you merely manipulate what data it sees in order to control it (kinda like college kids and the liberal media :lol: )

-C
 
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