97 5.7L Vortec: can I delete the post-cat OXYGEN SENSORS without much headache? (non-emissions test)

[Rayfer]

Quick summary:

1997 GMC Suburban, 5.7L Vortec, 2wd automatic, 207k mi, runs like new.

Both catalytic converters are shot. I learned this after replacing all four heated oxygen sensors (two tested bad, other two tested good, but figured it'd be better to replace all four at once).

I live in a non-emissions area.

The truck runs *great* save for the Service Engine Soon light staying on due to both cats being bad. Can I delete the cats and delete the post-cat O2 sensors? Is there a way a simple-minded person can "tune" the Vortec motor to not look for the post-cat O2 sensors?

I've tried the spacers...didn't work, the new O2 sensors are still sending enough of a signal back to trip the SES light.

I've seen videos on youtube of folks soldiering in a resistor, but I'd like to completely do away with everything which is unnecessary.

Any thoughts? Suggestions? Old army jokes? Sincere thanks in advance.

 

[Rayfer]

Turns out a Google search turned up some threads (on several forums) which didn't show up in each forums' own search function.

I may be looking at a custom tune, where the ECM is programmed to not read the signal from the rear O2 sensors. If that's the case, forgive my ignorance, is that something which can be done with a powerful enough handheld scanner, or do I need to find a specialty shop? Never done anything exactly like that before...

 

[shamrock246]

Blackbear can tune them out along with some standard tunes they have I've read it does wonders for these engines.

 

[Rayfer]

Thanks for the quick reply...just checked out their website. Looks like a good option.

 

[df2x4]

X2 for Black Bear Performance. Lots of other benefits too, your truck will be much more fun to drive. A word of caution, if you have the 4L60E automatic transmission, leave torque management and shift points alone. Their tune made a world of difference on my V6 truck.

 

[kennythewelder]

x 2 on the black bear tune. with that said, there is another way. I gutted my cats, then made some o2 simulators. I took some spark plug spacers, drilled a hole in one of them so the o2 sensor fits inside the spacer. Then I took a small piece of the honeycomb material I busted out of the cats. I ground this down to fit inside of the spark plug spacer, between the o2 sensor, and the exhaust pipe. This gives the ECM what it is looking for. You need two of these, one for each rear o2 sensor. Also the honeycomb is very brittle. I cut it with a hacksaw, but I could only pull the saw. when I pushed the saw, it broke the honeycomb material. This stuff makes a lot of dust when grinding, so ware a respirator.

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[Rayfer]

MUCH THANKS df2x4 and Kenny...have been reading more and this is *definitely* the way I want to go.

...and then the wife chimes in with "what if we want to sell the Suburban someday, and the buyer lives in the next county over with emissions-inspection testing"?

My response: We Will Never Have Any Reason To Sell This Truck. Something breaks, we'll fix it. 207k miles and still has 181-185 compression on every cylinder.

Appreciate the photos and the tips, Kenny. Helps paint a clear picture. Hoping to get started this weekend

 

[shamrock246]

I did the spark plug non fouler on my s-10 worked like a charm.

 

[miroslav]

I ran a pair of O2 sensor simulators for years while still having to pass an OBD2 e-check. The simulators will turn off the check engine light but the Catalyst Monitor in the ECM will just stay in Not Ready mode because they only see a flat response from the simulators.

It was a pain in the butt for me because the truck would fail the electronic emissions check. So then they would run it on the rollers with a sniffer up the tailpipe and it would pass every time. After a few years, the state stopped letting me run the alternative test and made me fix it.

I still have those sensor simulators and will never need them again. If you want them, PM me.

 

[kennythewelder]

I ran a pair of O2 sensor simulators for years while still having to pass an OBD2 e-check. The simulators will turn off the check engine light but the Catalyst Monitor in the ECM will just stay in Not Ready mode because they only see a flat response from the simulators.

It was a pain in the butt for me because the truck would fail the electronic emissions check. So then they would run it on the rollers with a sniffer up the tailpipe and it would pass every time. After a few years, the state stopped letting me run the alternative test and made me fix it.

I still have those sensor simulators and will never need them again. If you want them, PM me.

I obviously don't need them, but I am curious as to what type of simulators they are. I know that there are some simulators that are just a plug and play, and use resistors to make the voltage correct. The ones I made are mechanical as they use a small piece of the cat honeymoon material. IMO that is why they work so well. The rear o2 sensor still sees exhaust coming through the same material as it did when there was cats.