5 cents performance mod

[Yaross]

Hi everyone!

Anybody seen this article?:

http://www.autospeed.com/cms/A_110350/article.html?popularArticle

Fooling the ECM into thinking that air temperature is lower than it is actually is. Is it doable to our Yaris? or anybody tried this?

Thanks!

[eTiMaGo]

Doable? Yes.
Effective? Remains to be proven...

[Yaross]

i want to try it, any idea which wire is for the intake air temperature?

[ilikerice]

u should do a dyno before and after to see actual results.

[Viperoni]

It's debateable, some ECU's won't advance the timing and only add fuel with a colder IAT reading, but some like the Insight will do both.

That being said, running 11.5-12.0 AFR is too rich, especially when it used to run 12.0-12.5... but heck getting 5 degrees more timing ain't half bad (assuming the knock sensor doesn't kick in).

[Yaross]

u should do a dyno before and after to see actual results.

my yaris has not seen a dyno ever since I owned it!:redface:

anyway, I think the result can be seen if one has a scangauge II / OBDII and the thing to watch is the air/fuel ratio (I may be wrong on this) .

if the ECM is fooled by thinking it is getting a cooler air, it may allow a richer air fuel mix. theoretically, a liitle more fuel will give a little more power.

our yaris have a knock sensor, I think that will prevent any predetonation in case I have too much fuel in.

now, i have two problems:
1. I do not have the A/F gauges to see the results, i may have to rely on driver's instinct on this.
2. still I do not know which wire should i insert the variable resistor.

[Yaross]

It's debateable, some ECU's won't advance the timing and only add fuel with a colder IAT reading, but some like the Insight will do both.

That being said, running 11.5-12.0 AFR is too rich, especially when it used to run 12.0-12.5... but heck getting 5 degrees more timing ain't half bad (assuming the knock sensor doesn't kick in).

honestly, I do not know what AFR my car is running right now. but as you said, it is possible that I will not see any improvement if the knock sensor kick in.

only one way to find out...

[cali yaris]

it may allow a richer air fuel mix. theoretically, a liitle more fuel will give a little more power.

Not without more air too, or retarded timing. More fuel only (richer) will cause less power.

[Reactor]

Oxygen Sensor output will still determine the A/F ratio. Lower airtemp reading may allow ECU to advance timing a little bit though.

[Yaross]

guys, i really appreciate your responses. thank you very much!

so this is what i got so far:

1. it is doable (provided i know which wire is for the temperature sensor)
2. if my current AFR is 14.7:1(stoichiometric), getting it down to 12:1 should be fine. less than 12:1 will be too rich. too rich and i will not benefit and lose power instead.
(unfortunately, i do not have any gadget to measure / get the ECU reading, all i know, my engine is still completely stock)
3. if i was able to fool the ECU to advance the timing, i might get more power from using same amount of air with a little extra fuel.

and still i am stuck on item 1...

[eTiMaGo]

To be honest, the Yaris ECU already runs pretty rich. When driving normally it keeps at stoichiometric for best performance and emissions, and when you put your foot down, the ECU goes into open loop mode and is mapped quite rich (presumably to prevent any overheating problems, or detonation due to bad fuel, only Toyota engineers can answer this). It is highly unlikely that more fuel will give any power, quite the contrary it might be beneficial to lean things out a bit, but so far I believe nobody has any hard numbers on this.

As for your item 1, go look at www.etimago.com/yaris/repairmanual , the "engine control" file should show you the wires at the MAF/IAT sensor.

For item 3, I did some testing for another member not long ago with my scangauge showing the timing advance value, at full throttle:

http://dl.dropbox.com/u/1600280/Car%20Stuff/2011-08-10_11-05-31_425.mp4

It's a big file, sorry :p But you can see the advance reaching about 39 degrees. Might have gotten higher if I could have kept on going, I am not sure.

Anyway I am not saying it's a waste of time to do these kinds of mods, but don't expect magical results, and try to document and measure as much as you can :)

[ArmyYaris]

Its definetly something to look into and document, let us know the results if you do mess around (:

[Viperoni]

Oxygen Sensor output will still determine the A/F ratio. Lower airtemp reading may allow ECU to advance timing a little bit though.

Not if it goes into open loop during WOT and determines fueling off a pre-defined table in the ECU instead of reading the sensor.

[Yaross]

@eTiMaGo

Thanks, I check the manual and only had to time to read it today. Found the intake air temperature sensor explanation on page ES-97, simplified schematics on ES-99 and ground wire on MAF(orange-colored) on EWD page 87. Thanks also for sharing your test, I’m having second thoughts now.

@Viperoni and Reactor

Found some info about A/F sensor on page ES-76 and heated O2 sensor on ES-126. Still not clear to me what will happen and how much adjustment this two sensor will do as compared to the adjustment of the ECM from IAT chnages.

I already bought a cheap OBD2 scanner on ebay, hoping to receive it in two weeks time. I will do some initial data gathering before deciding to proceed or not.

[Captain Slow]

they sell cheap resistors on eBay that do the same thing...it will make your car run rich and stink like fuel. trust me.

[cali yaris]

^ Correct. For ten minutes, then the ECU makes the adjustment. No gain.

Here is my article on the subject:
http://www.microimageonline.com/forums/content.php/130-Performance-Chip-Fact-or-Fiction