Im wanting to take my cats off my 5.4 1997 f150 and am worried about what the oxy censors will do if i dont have ne cats on. If I do this than will it change the proformance of my truck? What is the best thing to do??

 

There are some hp gains from removing them.To take care of the sensors, get a chip to calibrate for them or get the MIL eliminators.I would get a chip from Troyer Performance. Give him a call and see what he can do for you.Or clink the link in my signiture to his site!

 

put a 1/4 volt resistor in the signal wire on the o2 wire harness i think it's the gray wire and it'll fix it,trust me its what i did,if you don't want to spend the money on a chip it's the cheap do it yourself route,i would suggest gettin the chip anyway though cause you lose quite a bit of low end takin off the cats,gain top end though,which if you get a chip and can rev it out to 5500 that'll help

 

1/4 volt or 1/4 watt ?

Also what resistance should it be ?

 

1/4 volt,it just reads the voltage output so the ohms shouldn't make a difference,you can get em at radio shack or any electronic place like that

 

Do you mean .25 (1/4) OHM resistor? A .25 ohm resistor wouldn't really be all that different from the lead resistance of the harness.

No such thing as 1/4 volt resistor. The resistance does matter since the computer will be looking for a certain level of voltage across it.

Would you connect the resistor to +12 volts or ground?

You may even need a voltage divider using two resistors.

Bob

 

The amount of resistance is what it takes to call it good or bad. The HO2S is heating up, and acts like a thermistor ( similar to how the MAFS works ) and the return voltage is compared to the supply voltage, and the drop = the amount of resistance, which equates from the lookup table to be what the O2 amount in the stream. The 4 wire HO2S uses a seperate heater circuit to increase the accuracy of the O2 sensors, vs the older 3 wire versions.
The resistance needs to be in the center of the operating range of the HO2S, or the resistance range to have the PCM in closed loop operation call the cat a working system, this makes the ohm value of the resistor the critical part of the equation.

BTW : ExpyBob is correct, no such animal as a 1/4 volt resistor. The specs are wattage and ohms , and if needed the tolerance of the resistor, or the margin of error in nothing, silver or gold bands after the color bands for the value on the smaller resistors.

BBROYGBVGW is the listing for the colors to find the value
1234567890 is the key.

Remember this by the phrase Bad Boys Rape Our Young Girls, But Violet Gives Willingly
The first 2 Bs are Black then Blue.
That was a stretch from EET school in the late 80's

 

Dug up the EVTM.

It seems that the resistor is between the colors Red w/ Yellow Stripe, and Red White Stripe.

This looks to be the supply / read circuit ( batt junction box for the RD/YE and PCM for the RD/WH ).

The heater circuit is from the PCM on Gray w/ Lt Blue stripe to Gray w/ Red stripe ( ground ). The other part is tied into the PCM to HO2S is a lead from the compuvalve module, which I don't know if this is the reference point, or something else ??

 

i don't know i'm not good with electronics,but i put 1/4 ohm resistor i guess on the gray wire which is the signal wire,i'm pretty sure. there was no red wire on mine theres white gray and black as long as you don't put it on the heater wires it should work if its on the input or output wire of the o2 sensor right? if you wanna be sure look up and be certain which one is the signal wire,that's all i know and it worked for me