Hey all,

I'm going to do the ECT mod for my 97 3.4L 4runner soon and had a quick question after searching and reading everything I could find on it.

I know that 1k POT is too large and it is suggested to find a 500 ohm one to use. But, I found both a 250 ohm one or a 500 ohm one to buy. Since the 1k is "too course", should I use the 250 ohm (to be even smoother) or the 500 ohm one then?

Just wondering if anyone else has tried it and has any advice.

Thanks.

 

The value of the restance you want should be no larger thn 1/2 the value of the pot......so if you want 150 ohm then you should have no larger than a 300 ohm pot. You want the resistance to fall in the midrange of the pot's achievable values. If there is no pot at say 300 ohm then go to the next largest 500 ohm or smallest 250 ohm (the smaller will give you a smoother time setting the exact value).

 

A 500 Ohm Linear Taper pot would be the one to use. Make sure it is Linear Taper and not Log Taper.

You can check out Mark's webpage on it.

Hope this helps.
G

 

Log taper would be a total bitch to tune.

 

Just a bit.

G

 

Thanks all for the help. I'll get the 500ohm one and use that then!

One more basic question, since the idle of the truck is raised after adjusting the thing, why can't I turn the idle of the truck lower before the install? Right now my idle is about 600 or so.

Just curious.

thanks!

 

The ECU is pre-programmed to idle at certain speeds based on Engine Temp. Since the ECT mod fools the ECU into believing the engine is colder, it raises the Idle Speed to compensate.

The only way to lower the idle speed on these engines would be to re-program the ECU and/or use a piggy-back controller to change certain sensor parameters such as the MAF signal or the Ignition Timing at Idle.

Hope this helps.
G

 

Cool. That totally helped me clear that up.

thanks!
Chris

 

YW!

Have fun!
G

 

I have a 1kohm Pot. coming for my ECT mod, but am unsure of the resistors needed. I know that I need a 1/4 watt 1k ohm resistor wired across terminals 1 and 3 of the pot to lower it's linear resistance to 500ohms, BUT should I get Carbon Film or Metal Flim resistors?

Steve

ps - I got a crazy flowing exhuast and a FIPK up front so this is the next step...lol

 

Dr. Zhivago, does anyone know how this mod will react w/ Gadgets new line of stuff @ urdusa?

 

Isnt this mod the basis for those "piggyback" device they sell on ebay for like $20. I saw some the other day and was curious.

 

Yep, that is exactly what they are!
.....and the ebay ones are not as good because they are not adjustable either.

 

Steve, Carbon Film are fine.

broknlgs24, If you have the URD fuel mods, don't bother with the ECT mod. I did get a few emails a while back from someone who had the S/C with the TRD 7th injector. He did the ECT mod and said there was a very noticeable improvement in the bottom end and midrange. Which is where the greatest benefits are felt with this mod, anyway.

Elway, the eBay mods generally target the IAT sensor, which on our engines, doesn't affect tuning the way the ECT sensor does. Modifying the IAT sensor won't, on our engines, gain you anything at all, so don't bother.

 

I gotcha, Im gonna read more into the the ECT mod then.

 

OOPS! Dr Z is correct, I must have been snoozing when I wrote that!
I was thinking the IAT (idle air temp mod) which is adjustable not the ECT mod.
Sorry!

 

IAT in this case refers to the Intake Air Temperature Sensor. There a lots of documented, reliable cases where modifying that sensor on a particular engine and tricking the ECU into believing that the incoming air is cooler than it actually is results in a performance gain in the way of Timing Advance and possibly a richer mixture. However, after playing with the IAT sensor on our engines extensively and monitoring the effects of it using my BR-2, I can say with utmost certainty that modifying it will do nothing for you.

Gadget even has a section on his website wherein he talks about putting a fixed value resistor in the IAT circuit and he says he could never tell a difference one way or the other.

Peace.
G

EDIT FYI, the IAT sensor is an integral part of the MAF on our engines. It's the brown, bulbous looking thing. On the 2nd Gens, it is built into the Vane AFM. On most GM's, it's upstream of the MAF or AFM and closer to the actual Throttle Body.

 

question...

couldnt you just use a 741 operational amplifier wired to the output wire to adjust the voltage to whatever value you wanted-- since 741's have high input impedance, they shouldnt adversely load the computer and could be altered without all the super-precise tweaking with pots. It seems that with an amplifier--even set to negative gain, you could tell the computer that the temperature is slightly different at any temperature, not just a fixed temp. does this make sense to anyone else?

T

 

I think the point is that the temperature sensor is set to allow the computer to correctly register the amount of incoming air. Simply richening the mixture does not gain you more power. The best ratio should be 14.7 and anything varying from this will cause a reduction in power, not a gain. It may be that it shows no difference or extremely little, but it doesn't seem much worth doing. I remain quite skeptical on this one but that's just me.

 

Jamie,

Actually, for best POWER, the AFR should be between 12-1 and 13.3-1. 14.7-1 is what gives you the most complete combustion for fuel economy and for the most efficient catalytic converter operation. The ECT mod bumps timing advance a little and slightly richens the AFR, which gains you some oomph down low and into the midrange until you reach the maximum advance built into the ECU.

It really does work. Granted, it's not an earth-shattering difference, but I have had plenty of people email or PM me who have done this and they all say the same thing. It makes a noticeable difference where it really counts: In the RPM range you use most.

Peace.
G