I was wanting to install a four blade racing fan on my truck and I was wanting to know how do i install an aftermarket fan on my truck with the current setop? another question what does the sensor on the outgoing side of the cat do and it i cut the cat off after the first sensor what would that change on my truck? Any help is appreciated.

 

why the 4 blade fan? usually the next step from stock is an electric fan.

the 2nd o2 sensor is measuring the cat's effecinecy. if you cut it out, take the rear o2 sensor out and add an O2 sim to the wiring harness. this way you will not get a CE light.

 

Going to a straight fan is going to rob you of horse power. If anything, you should go electric. I had a buddy who's fan clutch siezed on his truck and it turned it into a gutless wonder. Then since it was winter, he was able to run it without a fan until he got a new one and that truck was a beast.

 

i have both on mine, i just stuck a dual electric under the fan shroud and left the stocker on there, it runs really cool. about 180 on a hot day (80 or so) . my next project is to take a clutch from a durt bike and put it in between the stock ran so i can just shut it down. do any of you think there would be some sort of problem with that. I just thought of the idea one day and im just trying to run with it.

 

could you explain the way to eliminate the second sensor on the cat a little more please?

 

an o2 sim is a chip that plugs into the wires for the 02 sensor and makes your trucks computer think its there and working fine when its really not.

 

the whole point of going with an o2 sim is to avoid having a CE light for cat inefficiency. it is not supposed to affect your motors operating condition at all. That is what the front o2 sensor is for.

 

I have another more urgent question, this morning after i came back from mudding i noticed that my truck would not run up to full throttle. It will sputter and the check engine light will go from being on all the time to flashing. Is my cat stopped up? I planned on cutting my cat off right past the first sensor should that fix the problem? Help needed quick!

edit: Another thing, it is a lot quieter than before and when you get on the gas it moans from the intake. Did I **** it up by mudding or could the rain have hurt it or did the cat finally just stop up?

 

I have also noticed that after making a pass, I mean really giving it hell, I Will get the raw eggs smell coming from the exhaust, and going down the highway it will jump up in rpms and then go back down. It does that quite frequently.

 

did you check your intake for any debris? you can also check your cat to see if it's plugged...

The best way to test the cat is to have someone in the cab rev the motor to about 2000 or 2500 rpm's and put a temp gun on the input and output of the cat. the output should be around 50 deg hotter than the input for proper cat operation. if the temps are the same, the cat is not working, if the input temp is high and the output temp is low, you have a plugged cat and you should have it swapped out immediately.

I think the sulfer smell you get after a hard romp is the cat working extra hard... I get that sometimes on the M3 when i beat on it.