Reflashing the trucks computer after Cat/ Emission Delete

[IRQVET]

So I went ahead a removed both cats from my exhaust system and installed the Jegs Y pipe. I used the stacked spark plug arresters between the exhaust and the O2 sensors to fool the computer into thinking my cats were still there. However, my Tahoe is a California truck, so it has not 3 but 4 O2 sensors. My Y pipe only had 3 bungholes to plug in 3 O2 sensors. So now I have my 4th O2 sensor unplugged, and of course, the check engine light is on.

So has anyone ever “reflashed” your computer so you can delete the emmissions stuff? I live in a state with no smog requirements, but I have zero experience in this.

Talk to me Goose!

BTW, if anyone is looking to do this mod, its a pain in the a$$ and not as easy and straightforward as this video implies it is. Drilling out those 18mm spark plug arresters so they accept the O2 sensors took me several hours, as there is not alot of real estate (metal) left once you start boring/ hallowing them out, so its a painstakingly slow and tedious process.

 

[east302]

My 98 (49-state or non-CARB) has dual cats as stock so four oxygen sensors. On mine, one bank’s oxygen sensor is downstream of the flange after the converters (and wouldn’t be included with the y-pipe if your setup included the converters).

Edit: sorry, completely misread your original post. I’d delete my post but can’t quite figure out how to do it

 

[iamdub]

So I went ahead a removed both cats from my exhaust system and installed the Jegs Y pipe. I used the stacked spark plug arresters between the exhaust and the O2 sensors to fool the computer into thinking my cats were still there. However, my Tahoe is a California truck, so it has not 3 but 4 O2 sensors. My Y pipe only had 3 bungholes to plug in 3 O2 sensors. So now I have my 4th O2 sensor unplugged, and of course, the check engine light is on.

So has anyone ever “reflashed” your computer so you can delete the emmissions stuff? I live in a state with no smog requirements, but I have zero experience in this.

Talk to me Goose!

BTW, if anyone is looking to do this mod, its a pain in the a$$ and not as easy and straightforward as this video implies it is. Drilling out those 18mm spark plug arresters so they accept the O2 sensors took me several hours, as there is not alot of real estate (metal) left once you start boring/ hallowing them out, so its a painstakingly slow and tedious process.

I believe you can get those non-foulers on ebay already modded. Also, I think they have 90° ones for the tighter areas such as in your pic. Probably not as cheap as buying the non-foulers and drilling them yourself. But, what's your time and labor worth? I've seen small wads of stainless pot scrubber added between the two non-foulers to further filter the exhaust from the sensor. Keep this in mind if you get a catalyst inefficiency code.

Your '98 is OBD2, so it can be tuned by any shop worth their salt. Or, you can have someone (or a shop) weld another bung in the pipe for you to add that other sensor in. If you still have your original exhaust, you can cut the bung from it and weld that in. Adding that bung might be cheaper than getting it tuned, or maybe not. If you get it tuned, you could have some other items modified if you want such as top speed limiter raised or "removed", speedometer adjusted if you're running (and keeping) a non-original tire size, shift points and firmness altered, etc.

 

[IRQVET]

What type of shop can do this kind of a “tune.” Seems like it wouldn’t be your average Joe Blow achanic shop, but maybe I’m wrong?

 

[iamdub]

What type of shop can do this kind of a “tune.” Seems like it wouldn’t be your average Joe Blow achanic shop, but maybe I’m wrong?

Any speed shop worth visiting can tune. They all can turn off codes and adjust speed limiters, speedometers, etc. since all that entails is checking/unchecking boxes and typing in numbers. But, if you wanna tweak engine and trans parameters for power or improved drivability, that's gonna require knowledge and experience. Ask around or read up for reviews on facebook. There are people that can flash your ECM for you if they have the stuff (likely HP Tuners or EFI Live). Doesn't necessarily have to be a shop.

For kicks, I Googled "speed shop tallahassee fl" and the first hit is "Tallahassee Speed Shop". They look to be an import or more high-end place, but I'm sure they can point you to a handful of people and/or places to tune a GM.

 

[east302]

I’ve never used them, but Black Bear Performance is commonly used by a lot of GMT400 owners.
HP Tuners is another one…

Blackbear tune to disable security, rear O2s...anything else???

Had my cats cut out since they were plugged solid and may have also installed a magnaflo muffler at the same time. Then as of late, my security system kicks in everytime I start my truck. Enough is enough so I ordered a tune from Blackbear to get rid of the rear O2 sensors and disable the...

www.gmt400.com

 

[iamdub]

^^^ Yup. If you're on facebook, you could ask on a couple local car pages if anyone has HP Tuners. For just an engine tuning credit, it'd probably be $50. Maybe see if someone would do it for $50 and a case of beer.

Or, I bet you could find a welder that'd put those bungs in your exhaust pipe for a case.

 

[east302]

That’s a good idea.

Quick aside, your avatar makes my eyes hurt

 

[iamdub]

That’s a good idea.

Quick aside, your avatar makes my eyes hurt

That's the second comment on my avatar today! What's cool is that it's not the pic doing it. It's your brain and mind trying to process what it's not accustomed to. Which is the true antagonist? Which is more convenient to blame?






















...Okay, so it's just an annoying avatar.

 

[swathdiver]

Which is more convenient to blame?

You!