There are available from many sources (mostly e-bay) resisters that attach to your intake air temp sensor or coolant temp sensor and fool your ECM into thinking the engine is running cooler that it is, and bumps your timing. They claim to add 20 hp for about $20. Anyone use one of these, any comments. If I'm running one should I still bump my base timing a few degrees as I know my 305 will enjoy a little timing advance?

 

why waste the 20 bucks on a resistor that costs 30 cents

 

One would fist have to ask themselves, "Why does my car have a computer?"

 

sqzbox, can you please elaberate.....what is the difference between advancing the base timing and what the EST is doing? anyone?

 

It's a bad idea to screw with the ECM, and fool it into thinking the car is colder than it is.
You can go out there and bump up your base timing yourself, at least that way the computer will only pull timing if it senses a knock.
You may want to look into chip burning info if you want, that gives you full control over your timing curve.

 

those resistors fool the ecm into thinking its cooler that it actually is, which will give the engine more fuel that is not needed. but what alot of people dont realize is that the o2 sensor with see this extra fuel and in turn learn it, and after 20 minutes of driving like this, it will be back to normal, not giving it the extra fuel. but at wot the 02 is ignored, so you will get some more fuel at wot, but that could actually hurt your performance by having and overly rich condition. the people that sell this garbage dont do their research and just want to steal your money. if you still want to try this, by all means do it, but dont buy from this guy for 30 dollars, go to radio shack and get the resistor yourself its 25K ohms 1/4watt.

back when i got my super charger kit on my honda it came with this resistor to put on the iat, and i thought that it might work, but i was getting all kinds of detonation over 4000rpm and 10psi. i ditched the resistor and the fmu and did the real tuning through prom editing and have yet to see any detonation, and im getting better gas mileage. do yourself a favor and get some prom burning equipment like sonix said, it gives you full control over your computer.

 

or just lengthen you harness and put the sensor in the air filter can. I think the V-6 Firebirds have them there.

 

I think the whole idea of fooling the computer is to try and keep it in open loop (which is not good for emisions or fuel milage) It will probably work for a while but the first time you idle for a long period or sit in a drive through restaraunt and your temp goes up to 190* + and then cools back down after you start driving again your SES light will come on because your computer thinks your going from closed loop back to open loop. In that case, it's going to send a signal to the EGR control solinoid to cut vacuum to the EGR valve and that is not normal. Next thing you know, your SES light comes on and the computer will retard your total advance. By putting that resistor in there your setting yourself up for more problems than it's worth.

 

Yeah it's a joke don't bother. Yes it will fool the ECM but as mentioned the ECM will adapt, that's what they do. Plus that is fairly important information that the ECM needs, why would you want to lie to it?

 

Big thanks to all, I'll steer clear and do things the right way!!!!

 

Actually, it wont do anything of the sort. These cars have O2 sensors, not A/F sensors. They dont see excessive fuel, only oxygen content in the exhaust. With the IAT reporting the lower temp, the car wont make adjustments to remove the fuel. Why not just unplug the damned thing, and make it default to -40? It would pretty well accomplish the same task. Lose MPG and gain nothing.

 

while it is true that its an O2 sensor, it still sees whether or not there is too much oxygen or not enough. it doesnt just read only one way. the oxygen sensor has swing points that try to average a 14.7:1 ratio to keep the cat happy and to help with emissions. if you install the resistor, first it will inject more fuel because it thinks the temps are lower, then after the O2 sensor senses too much fuel or not enough "oxygen" it will begin to pull fuel until the swing points will average 14.7:1

as for unpluging the sensor, i dont think it will read at -40. i think it will just throw a code and go into limp mode.

 

Well, it most usually will. I dont make this stuff up, I have ASE certifications and do this for a living. When lack of input is sensed it will most definately default to a full cold reading. This is normal on almost all cars. GM will at that point usually disable block learn because of the situation. This will remove the ecms ability to Fix the fuel ration.

And actually, you are off again. The o2 sensor will go lean and rich as the ecm recalculates fuel, it doesnt actually average 14.7:1. These crosscounts are more measured for speed of occurance, not amplitude of voltage signal.