ls15244

hey guys any cheap homemade ideas on how to fool the computer would be appreciated i know about the sims but just wondering if there is any resistor trick or something any help would be great thanks

horist

no cheap home made tricks as far as I know... since you gutted the cats the rear O2s are telling the PCM that the cat's are busted....

either need to have the PCM modified to turn the codes off or get O2 Simulators

ls15244

man that kinda sucks for my stang they were like $50 these are like $89 wonderful gm thanks for the reply

jimmyblue

iTrader: (11)

Just find a used pair of sims (they seem to
be going cheaper as more people get access
to tuning or their own software) or find a
buddy with HPTuners, same model*year,
who can help you out.

ls15244

hey jimmy blue do u have that software?? if so i am in melbourne and would pay ya

jimmyblue

iTrader: (11)

As long as we're talking Melbourne FL and not
Australia there's no charge - only, I have an
'02 F-body and you'd have to as well. Though
there are some other guys local getting into it
with other model years. What's your vehicle?

Won't be back home until the weekend tho...
in Hotlanta for another couple of days.

ls15244

yes lol in melbourne fl mine is a 02 z-28 with the m-6 man i would really apreciate it my name is jon here is my num 321 302 8887 and whenever is good for u man let me know

Catskynr

Hope you got it done, but thought I'd post this for the FYI for others in a quandry...


Post cat O2s are designed to make sure the CATs are performing their function. As most already know, the pre CAT O2s are for A/F adjustments. The PCM wants to see a best average vector of 950mV on the pre-CAT O2s based on a comparator circuit in the PCM. On the post CATs, the PCM wants to see 450mV average based on a comparator circuit to guarantee the CATs are performing. So what happens when you remove those CATs, 950mV is read post-CAT. So how do we fix this? Easy.

I provide these instructions based on my own findings and experiments using my own tools in my own garage. If your car blows up after you perform this modification, don’t blame me.

The first mistake people often make is trying to trick the PCM by using a resistor inline on the O2 sensor. After all, the post cat O2 sensors are now outputting 0.95 volts instead of an expected 0.1 to 0.8. A resistor of value X, where value X is whatever your friends brothers dog walker’s nephew runs on his Honda with 100% success. The problem is our PCM uses a comparator circuit mega-ohm measurement device, meaning just about no matter what kind of resistance you put in, the full amount of voltage will still be seen. Remember, resistance does not drop voltage, it limits current. If the PCM were to apply a load, then resistance would inadvertently drop the voltage it saw. So this is the right idea, but the wrong method. Next mistake I’ve seen is a complicated circuit that takes the O2 sensor signals, processes them, and re-transmits them at a lower value. Geeze!!! Talk about overkill. While that will work, how about the most simple and cheap design possible!

Standard Diode from radio shack, P/N: 276-1141

The average rectifier diode is a one-way valve. It has a voltage drop when current passes through it, which is usually around 0.5 volts. There are millions of different diodes that can greatly alter that figure, but for our purposes we will use that figure because it’s EXACTLY what we need. Your cats aren’t burning off any of those unburned hydrocarbons when they’re laying in a million pieces in the trashcan, so there is plenty of oxygen present as far as the downstream O2 sensors are concerned. They’re putting out 0.95 volts. Pass through this lovely $1.29 incarnation, and whoopee! It’s 0.45 volts. What does the PCM expect? 0.45 volts is within perfect specifications.

You want to place the diode inline with the O2 sensor output. Not the 5V reference voltage, and not the heater circuit. You can find which is which by placing a voltmeter on the O2 sensor wires. The one with a varying voltage is the one you want. On most 4 wire O2s you have two matched color wires(heater circuit) and two variable colors (one is ref, other is sensor output)
Once you know which wire is your sensor output, remove the O2 Sensor/s and cut the (sensor output) wire, crimp in the diode with the silver bar facing away from the O2 sensor (toward the connector). If it’s backwards, your PCM won’t see any voltage at all. So if that happened, now you know why. Make sure you cut enough of the wire to make up for the length of the conglomeration. It’s about 1.5” if you use two crimp connectors and cut the diode leads to about 0.5” long. Bonus points if you heat-shrink this connection. Double points if you trace this/these wires back to the PCM side and do it there. If done at the PCM, the silver bar faces the PCM. All this allows positive voltage to flow from the sensor through the diode to the PCM. Re-install your O2/s.

When you’re done, the voltage drop occurs and all is good. Clear those codes and enjoy!

00ws6trans

The oxygen sensor harness has the following wires for the oxygen sensor:
Purple
Brown (Ground)
Tan
Brown (12v+)

Which is the signal, heater wires?

Thanks!

jxaxsxoxn

iTrader: (2)

If you're ever about an hour and a half south, near port st lucie, I can delete the O2's for you also. I'm on vacation this week from work.
BUT it would be best to wait for Jimmy, he knows way more about tuning than I do.
I can do the simple stuff though.