Topic: O2 Sensor Simulators

All,

I'm working on a 2006 Pontiac Grand Prix for Lemons.  3.8L engine.  I was going to cut out the cats and I would like to have clean diagnostic codes so I can have the MIL be a dummy light for during the race.  I was also wanting to avoid spending the money on a tuner.

This is the only O2 sensor simulator I've found that is specifically for this car. magnumtuning. com/en/detail/ez-cel-fix-oxygen-sensor-simulator/pontiac/grand-prix and I wanted to see if this would be a good option to go with, or if it would be better to just leave the cats in.

Anyone have any recommendations?

Thanks in advance.

Re: O2 Sensor Simulators

I would think you'd want to leave the 02 sensors in a modern EFI car especially since you'll be operating it WFO a fair bit of the time.  My understanding is if you have a dead cat, installing sparkplug anti-oil fouler adapters under the 02 sensors is enough to fool the system that the cats are still good and not trigger a CEL.  I've never tried it myself.

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Re: O2 Sensor Simulators

I'm not planning on removing the upstream sensor.  The downstream sensor has no purpose except to monitor the cat.

Re: O2 Sensor Simulators

cheseroo wrote:

I would think you'd want to leave the 02 sensors in a modern EFI car especially since you'll be operating it WFO a fair bit of the time.  My understanding is if you have a dead cat, installing sparkplug anti-oil fouler adapters under the 02 sensors is enough to fool the system that the cats are still good and not trigger a CEL.  I've never tried it myself.

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I've done this on multiple miatas and an 06 civic Si. Sometimes you have to "calibrate it" with different sized holes, stacking multiple, and/or stuffing some header wrap in there, but it's not too bad. Graph the downstream o2 sensor to guesstimate if it needs more or less choke. It's easy, never had to redo it more than twice until it's fixed for good.

Full Ass Racing
#455 Piñata Miata

Re: O2 Sensor Simulators

Do you have a recommendation on where I could find info on what the downstream o2 sensor graph looks like from the factory?  The current cat is clogged so I can't go off of the current reading.

Re: O2 Sensor Simulators

Basically it is a slow sign wave.
I have seen and done the oil non foulers several times and i have seen them work with great results.
A Tuner honda came in when I saw it first.
NY state plugs in for Inspection. The Kid who owned the car lied to me and said the Cat was there (it wasn't) I was astonished that it passed.
Just put the non foulers on the post Cat O2s,It will work fine!
Manny

Re: O2 Sensor Simulators

you don't need a simulator, you just need an O2 spacer. We pulled the cat from our '08 saab and I put the downstream sensor on a 90° spacer and the car is as happy as it was when stock.

20+ Time Loser FutilityMotorsport
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2008 Saab 9-5Aero Wagon
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Re: O2 Sensor Simulators

The voltage coming out of the downstream O2 sensor behaves the same way that the upstream sensor does - its basically a 'switch' and puts out less than 0.5V when the exhaust is lean (above 14.7 AFR) and above 0.5V when the exhaust is rich (below 14.7AFR). That's why they call it a narrowband sensor, it can only determine if you are above or below stoich. That's why a wideband O2 sensor is so useful, it can tell you exactly what the mixture is.

If the cat is working as designed, it will remove oxygen from the exhaust stream, so the downstream cat should be reading a rich mixture (above 0.5V). If the ECU sees a lean mixture (less than 0.5V), it assumes that the cat is bad.

We Audi Be Faster
'85 Audi Coupe G(in &) T(onic)

Re: O2 Sensor Simulators

FYI, at least get a good scan tool that can do the security delete even if you do not get tuning software.  This is assuming you have the silly GM transponder key.  All the "good" methods of defeating the passive key are failure prone on a GM from our experience except turning it off in the software.

Also as team with more than a dozen races on the Series 1.5 3800 NA...your trans is your weak link.  Do everything you can to keep it cool and bring a spare.

10 (edited by atlantis737 2021-06-09 10:30 AM)

Re: O2 Sensor Simulators

Thanks OnkelUdo, can you recommend a scan tool (wallet minded if possible)?  I have been trying to research them but it's not quite as clear/concise of information as with Fords (my background).  I have been looking at the Tech2 from obd2tool.com but the description is a little confusing and makes me think it might be a fake...

Thank you everyone for the information on spacers.  Greatly appreciated.

Re: O2 Sensor Simulators

I have a clone tech2 for the saab, if you want to know anything about the tool let me know. It's a powerful tool used by GM for a lot of things. it does require a card with the right software for your car to work. But it's crazy useful for GM cars.

20+ Time Loser FutilityMotorsport
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2008 Saab 9-5Aero Wagon
Retired - 1989 Dodge Daytona Shelby 2011-2015 "Lifetime Award for Lack of Achievement" IOE, 3X I got screwed, Organizer's Choice

Re: O2 Sensor Simulators

I'd love any info you can give me.  I'm trying to sift through the clone Tech 2s versus just biting the bullet and getting an HP Tuner.  I used to have a clone Ford VCM which was a nightmare, so I'm hesitant to mess with a clone Tech 2.  Any advice would be appreciated.

Re: O2 Sensor Simulators

So the tech 2 is a godsend for diagnosis and minor changes on modern (ish) GM cars. It's not a tuner, though there are ways (I think) to flash ECUs with it. For the Saab I have another board for flashing our ECU and the tech 2 is just for diagnosis and working on modern electronics. Example, the TWICE unit in the saab failed a few years ago, and since that unit does security the car wouldn't fire up. The only way to make the car work again was to program in a new TWICE unit, which required the tech2. We were able to steal the TWICE from my sister's car, program it in, finish the race, then program that unit back into her car and get her home at the end of the weekend.


I don't know much about the HP tuner stuff at all, I don't know if it has the security features to program modern boxes in and out of the car. It very well may offer you a tuning solution if that's your only goal though.


The tech 2 is not fun to use. It's super old tech, it's slow, mine doesn't work when it's cold, but it has paid for itself already in being able to recover from failures and finish a race. I think they're worth it, but your mileage may vary.


Theoretically, if you have a computer with a PCMCIA slot you can buy 1 memory card and then flash the different software packages for different vehicles onto it as you need it, so it can be used with more cars. I haven't tested that part though since I own no other GM vehicles other than the saab.

let me know if you have any specific questions.

20+ Time Loser FutilityMotorsport
Turbo Dodge Powered E36 Build
2008 Saab 9-5Aero Wagon
Retired - 1989 Dodge Daytona Shelby 2011-2015 "Lifetime Award for Lack of Achievement" IOE, 3X I got screwed, Organizer's Choice

Re: O2 Sensor Simulators

Here's a thing I learned about check-engine codes from a Volkswagen team (naturally) at NJMP: Some cheap OBDII code readers have a button that resets the engine codes and will do it on the fly without turning off the engine. They moved the OBDII port to within the driver's reach so when (not if) it goes into limp mode (about 2-3 times a race if all goes well), they just coast for a bit and mash the reset button. It'll clear the codes and the engine tends to be happy again for a while.

Is this a long-term solution? I dunno, but it works for them.

Eric Rood
Everything Bagel, 24 Hours of Lemons
eric@24hoursoflemons.com

Re: O2 Sensor Simulators

therood wrote:

Here's a thing I learned about check-engine codes from a Volkswagen team (naturally) at NJMP: Some cheap OBDII code readers have a button that resets the engine codes and will do it on the fly without turning off the engine. They moved the OBDII port to within the driver's reach so when (not if) it goes into limp mode (about 2-3 times a race if all goes well), they just coast for a bit and mash the reset button. It'll clear the codes and the engine tends to be happy again for a while.

Is this a long-term solution? I dunno, but it works for them.

This is such a VAG solution...how will they know the engine is running without the check engine light, though?

Re: O2 Sensor Simulators

Dave Morrow is your guy when it comes to the pontiac 3800.

He has put them in everything.

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