2016 Z06 Headers No Tune?
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Instructor
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2016 Z06 Headers No Tune?
Hi all, I'm looking at a 2016 Z06 that has a set of Kooks headers and X pipe but the current owner has not had a tune done. Currently throw CELs P0420 and P0430 (cat inefficiency). I've read that the car gets air/fuel ratio info from the O2 sensors and without a proper tune the car could run lean, and the supercharger doesn't help either. He drove it for 2,000 miles and said the car runs like new (has 16,000 miles). Other than the exhaust and Corsa CAI, its stock.
He's going to send it to his Chevy dealer to have the O2 wiring and sensors inspected, but I wanted to ask you all if it there's any danger driving the car without a tune for that long. I just don't want there to be anything hidden that will show its face later.
What are the potential issues running it like this would cause? If I buy the car I'll be getting a tune ASAP. Do headers really make these cars run dangerously lean or would you be able to drive it how you want and the only nuisance is the CEL? Would you be able to get into boost without worry?
Any help is much appreciated, thanks!
He's going to send it to his Chevy dealer to have the O2 wiring and sensors inspected, but I wanted to ask you all if it there's any danger driving the car without a tune for that long. I just don't want there to be anything hidden that will show its face later.
What are the potential issues running it like this would cause? If I buy the car I'll be getting a tune ASAP. Do headers really make these cars run dangerously lean or would you be able to drive it how you want and the only nuisance is the CEL? Would you be able to get into boost without worry?
Any help is much appreciated, thanks!
Pro
Joined: Feb 2023
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The car absolutely needs a tune to run correctly. I'm assuming he has the Kooks xpipe with no cats in it. Since the car wasn't tuned it is expecting the readings on the down stream O2 sensors to be different than the upstream sensors.
I would be very cautious buying a car from someone that would mod it and then not care to have it tuned. I would have a PPI done on it and ask them to do a compression check.
I would be very cautious buying a car from someone that would mod it and then not care to have it tuned. I would have a PPI done on it and ask them to do a compression check.
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Thanks for the input, Yeah I was wondering why he hasn't gotten a tune just from the fact that the CEL would be annoying let alone the risk of something happening. He says the X pipe has high flow cats on it.
He is going to have the car inspected at the Chevy dealer and I can tell him to have the compression tested for sure. There are many other Vettes on the market but I just wasn't sure if there was any considerable risk running it like that.
He is going to have the car inspected at the Chevy dealer and I can tell him to have the compression tested for sure. There are many other Vettes on the market but I just wasn't sure if there was any considerable risk running it like that.
Race Director
Joined: Apr 2000
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From: Texas
Thanks for the input, Yeah I was wondering why he hasn't gotten a tune just from the fact that the CEL would be annoying let alone the risk of something happening. He says the X pipe has high flow cats on it.
He is going to have the car inspected at the Chevy dealer and I can tell him to have the compression tested for sure. There are many other Vettes on the market but I just wasn't sure if there was any considerable risk running it like that.
He is going to have the car inspected at the Chevy dealer and I can tell him to have the compression tested for sure. There are many other Vettes on the market but I just wasn't sure if there was any considerable risk running it like that.
- Didn't install the aft o2 sensors. They have zero impact on fueling. Their sole purpose for existing is to measure cat efficiency for emissions
- The cats he installed are less efficient than the factory cats and therefore the codes set thinking the cats are failing.
The cars are a tad rich from the factory (although not as much as in the "old days"). Nonetheless, the PCM has plenty of range to adjust fueling if the FRONT O2 sensors (which do provide fueling information) are telling the PCM the mixture is lean. Looking at the Long Term Fuel Trims will tell you what it's doing.
More than anything, besides the annoying Check Engine light, he's leaving power on the table by not getting it tuned.
Thread Starter
Instructor
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Yeah I don't really have a warm and fuzzy feeling about it, I was just at a loss as to if this was more of an annoyance than having something go wrong with the car.
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P0420 and P0430 means he did one of two things....
The cars are a tad rich from the factory (although not as much as in the "old days"). Nonetheless, the PCM has plenty of range to adjust fueling if the FRONT O2 sensors (which do provide fueling information) are telling the PCM the mixture is lean. Looking at the Long Term Fuel Trims will tell you what it's doing.
More than anything, besides the annoying Check Engine light, he's leaving power on the table by not getting it tuned.
- Didn't install the aft o2 sensors. They have zero impact on fueling. Their sole purpose for existing is to measure cat efficiency for emissions
- The cats he installed are less efficient than the factory cats and therefore the codes set thinking the cats are failing.
The cars are a tad rich from the factory (although not as much as in the "old days"). Nonetheless, the PCM has plenty of range to adjust fueling if the FRONT O2 sensors (which do provide fueling information) are telling the PCM the mixture is lean. Looking at the Long Term Fuel Trims will tell you what it's doing.
More than anything, besides the annoying Check Engine light, he's leaving power on the table by not getting it tuned.
Race Director
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From: Texas
This is good info, thanks a lot. SO you think the PCM would have enough leeway to keep the car running safely if the front O2 sensors are disconnected? It was my understanding either the front of rear O2 sensors could throw the code. One tuner I spoke to said as long as the the wiring is fine and the REAR O2 sensors are the ones throwing the codes, then he could tune that all out easily. He mentioned that if the FRONT O2 sensors are causing the code it would be risky to drive around like that, and with 2,000 miles already clocked on it I would avoid that 100%.
By definition, cat efficiency is measured post-cat. It's Sensor 2 on each Bank. There is a very Very slim possibility an upstream exhaust leak can cause this, but it would be a million to one odds on top of that that you'd have exhaust leaks on both sides causing two codes.
It takes less than 15 minutes to tune the codes out from the time the tuner opens the laptop until he closes the laptop and puts it away.
Ask him. Does it have front o2s hooked up? What about the rears? Tell him to send pictures.
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Modern PCMs have a LOT of leeway but the fronts aren't disconnected.
By definition, cat efficiency is measured post-cat. It's Sensor 2 on each Bank. There is a very Very slim possibility an upstream exhaust leak can cause this, but it would be a million to one odds on top of that that you'd have exhaust leaks on both sides causing two codes.
It takes less than 15 minutes to tune the codes out from the time the tuner opens the laptop until he closes the laptop and puts it away.
Ask him. Does it have front o2s hooked up? What about the rears? Tell him to send pictures.
By definition, cat efficiency is measured post-cat. It's Sensor 2 on each Bank. There is a very Very slim possibility an upstream exhaust leak can cause this, but it would be a million to one odds on top of that that you'd have exhaust leaks on both sides causing two codes.
It takes less than 15 minutes to tune the codes out from the time the tuner opens the laptop until he closes the laptop and puts it away.
Ask him. Does it have front o2s hooked up? What about the rears? Tell him to send pictures.
The tuner said it would be a very simple tune to get everything cleared up, I just want to be 100% sure there's no chance the motor could be somehow messed up from driving it that long without a tune before making the 12 hour drive.
Instructor
Joined: Jul 2020
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From: Raleigh, NC
Another thing is those are permanent codes. If the headers don’t have cats working correctly the cats will need replaced before the codes will clear. HP tuners can’t turn off that code once it is set.
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From: Texas
Race Director
Joined: Apr 2000
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From: Texas
....and I do want to add some clarity to what I mean. You can go in with HP Tuners and turn the codes "off" such that the tests will no longer run in the future and you can also turn off the SES light so you don't have to stare at that any longer. If you log the PCM, you will see the codes so they're still "there"...just not affecting anything.
As Random Dan pointed out, if you really want it completely cleared out of the system, you need to install sufficient cats, install aft 02 sensors, and run through a few drive cycles until the PCM passes the test.
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....and I do want to add some clarity to what I mean. You can go in with HP Tuners and turn the codes "off" such that the tests will no longer run in the future and you can also turn off the SES light so you don't have to stare at that any longer. If you log the PCM, you will see the codes so they're still "there"...just not affecting anything.
As Random Dan pointed out, if you really want it completely cleared out of the system, you need to install sufficient cats, install aft 02 sensors, and run through a few drive cycles until the PCM passes the test.
As Random Dan pointed out, if you really want it completely cleared out of the system, you need to install sufficient cats, install aft 02 sensors, and run through a few drive cycles until the PCM passes the test.
Race Director
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From: Texas
Thanks guys. We will see what the Chevy dealer finds out. I know that I would want the codes wiped out (not having them still lying in the background), just because I don't know how the emission test reads the codes. I don't know if it logs the PCM to scan for a code or it it does a more superficial search. I'd rather be safe than sorry so we'll see how it goes.
Complete setup on eBay for example.... https://www.ebay.com/itm/40491622930....c101506.m1851
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If you really like the car because of its color and/or options you were looking for, etc, and it just has headers, you can always pick up used exhaust manifolds/cats/intermediate pipe and put it back to stock. All 2014-2019 Stingrays, Grand Sports, and Z06s use the same parts so there's a pretty big used parts market to draw from (it's not unusual to see pristine parts listed in the "C7 Parts for Sale" section on this forum). Sell the headers to recoup some of the cost.
Complete setup on eBay for example.... https://www.ebay.com/itm/40491622930....c101506.m1851
Complete setup on eBay for example.... https://www.ebay.com/itm/40491622930....c101506.m1851
Burning Brakes
Joined: Jan 2019
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From: Louisiana
I do really like the car, has the Z07, carbon package, comp seats, etc., and I don't mind the headers, I actually like them, I'm just worried about there being the potential for internal engine damage due to him running it without a tune for so long. If it was tuned right after the install I would have gone to look at it already. Your advice has really helped me a lot, I greatly appreciate it! I think it's just a waiting game now, the car is going to be inspected on the 29th so I'll decide what to do from there.
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I definitely plan to, not like we're talking about a $5,000 car lol. You would think headers alone wouldn't cause any problems but I just want to be 100% sure.