Mreza321

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hi I have 2018 z06. noticed in the last week and a half when I floor it the car almost lags or kind of chokes before going. wondering if anyone knows what it could be?
 
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Mreza321

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Bad, or low octane gas?
that's what I thought which was surprising as I was using 94 at petro and did not have access to it so did shell 91 which apparently is up there. since then have run 2 tanks with 94 but still same issue
 

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Petro 94 is an ethanol blended gas but not sure if this matters.
 

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that's what I thought which was surprising as I was using 94 at petro and did not have access to it so did shell 91 which apparently is up there. since then have run 2 tanks with 94 but still same issue
The only gas I ever put in my '17 Z06 was Shell 91. It always wanted to go.

There's a chance (this is likely far fetched) that due to Covid-19 the 94 you're getting is stale / old in the underground tank. Not too many customers use it in good times, and times ain't been so good lately.

If you think it's gas related, a 1/4 - 1/3 can of Seafoam into a full tank. (Won't hurt anything....I use it as stabilizer for each gas engine I've got)
 
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hi I have 2018 z06. noticed in the last week and a half when I floor it the car almost lags or kind of chokes before going. wondering if anyone knows what it could be?
A 2018 still has warranty so I think your best bet is to take it either to the dealer or trusted mechanic. There are too many variables and the problem is too general to be able to effectively diagnose on here without more specific information. I'm presuming there are no active codes as you didn't mention a check engine light.
 

Mreza321

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A 2018 still has warranty so I think your best bet is to take it either to the dealer or trusted mechanic. There are too many variables and the problem is too general to be able to effectively diagnose on here without more specific information. I'm presuming there are no active codes as you didn't mention a check engine light.
I think that's a good idea. yes no codes showing up.
 

Mreza321

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A 2018 still has warranty so I think your best bet is to take it either to the dealer or trusted mechanic. There are too many variables and the problem is too general to be able to effectively diagnose on here without more specific information. I'm presuming there are no active codes as you didn't mention a check engine light.
but the problem is with the dealer I feel like they never are able to replicate the problem and ends up being a waste of time. like I was having this issue where getting the car to the 1st gear was an issue and to them it wasnt and finally the issue went away itself!
 

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@Mreza321 I agree with the dealership advice above from @Creedence85

In 3rd and above (M7) your car should snap your head back over 3000 RPM. Below that RPM in higher gears the 2 C7 Zs I owned were like a city bus with acceleration. But in 1st and 2nd it should be scary at any RPM. Sounds like something is not right and you may have been put in a limited power mode. If your car did see some bad gas it's possible it went into a knock protection mode. Or you have an issue with your drive mode computer. Maybe the car thinks it is in weather mode?
I have a very good scanner that supposedly sees all systems, and it will not see everything. The GM machines are designed to literally see anything and everything. If you don't trust your dealership someone here will know a good service dealership near you.
 
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Mreza321

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thank you ddgermann actually you might be on to something as I noticed everytime I stop the car and without turning it off it switches to touring mode🤔
 
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Have you verified if there is any air in the sc intercooler setup? On hot days, the iat will be high and air in the system is detrimental to performance. Look down beside your air cleaner towards the front of your car. The reservoir is located there. Should be filled to top with no more than a few loonies of air bubbles. Odds are you have air there then you have air trapped in the sc cooling bricks at the top of the engine. Due to how 17+ cars have tilted cooling bricks, you will never get that air out using normal means.
 

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Need to build a setup to pull vacuum and tilt the car up so the fill system is the highest point so air can be removed.
 

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ddgermann

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Have you verified if there is any air in the sc intercooler setup? On hot days, the iat will be high and air in the system is detrimental to performance. Look down beside your air cleaner towards the front of your car. The reservoir is located there. Should be filled to top with no more than a few loonies of air bubbles. Odds are you have air there then you have air trapped in the sc cooling bricks at the top of the engine. Due to how 17+ cars have tilted cooling bricks, you will never get that air out using normal means.


Very interesting point. However would the car not throw a code or dash warning if it goes into a protective mode? That is a real question as I have not experienced anything like that with my 15 or 17 Zs. Did this happen to you?
I find it interesting his car bounces back to touring mode every time he stops. Neither of mine did that either. That sounds like he has a computer problem.
 

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Limp mode is only triggered if the engine temp becomes unmanageable. Limp mode will not trigger in street driving unless you really overheat your engine. If iat is too high, you will have severe timing pull and it'll seem like its lagging. There is no code for high iat just low power. Fuel octane is incredibly important too during high temps as knock will come on sooner and cause even more timing pull.

I run boostane in my fuel for an effective 96 octane with 91 no ethanol as base fuel. I can run my 17 z06 fairly hard on street with full ac and not see any detrimental power loss, data logs show only timing gets pulled when my iat is too high, but once the car is moving, I get it back as my intercooler is well bled.

The reversion to tour mode on stop seems like a computer glitch, I ran a light track day in heat and air in my sc and aside from some power loss never saw my car modes switch out while on.
 
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ddgermann

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Limp mode is only triggered if the engine temp becomes unmanageable. Limp mode will not trigger in street driving unless you really overheat your engine. If iat is too high, you will have severe timing pull and it'll seem like its lagging. There is no code for high iat just low power. Fuel octane is incredibly important too during high temps as knock will come on sooner and cause even more timing pull.

I run boostane in my fuel for an effective 96 octane with 91 no ethanol as base fuel. I can run my 17 z06 fairly hard on street with full ac and not see any detrimental power loss, data logs show only timing gets pulled when my iat is too high, but once the car is moving, I get it back as my intercooler is well bled.

The reversion to tour mode on stop seems like a computer glitch, I ran a light track day in heat and air in my sc and aside from some power loss never saw my car modes switch out while on.


Excellent follow-up information. Thanks a bunch. :thumbs:
 

Mreza321

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Limp mode is only triggered if the engine temp becomes unmanageable. Limp mode will not trigger in street driving unless you really overheat your engine. If iat is too high, you will have severe timing pull and it'll seem like its lagging. There is no code for high iat just low power. Fuel octane is incredibly important too during high temps as knock will come on sooner and cause even more timing pull.

I run boostane in my fuel for an effective 96 octane with 91 no ethanol as base fuel. I can run my 17 z06 fairly hard on street with full ac and not see any detrimental power loss, data logs show only timing gets pulled when my iat is too high, but once the car is moving, I get it back as my intercooler is well bled.

The reversion to tour mode on stop seems like a computer glitch, I ran a light track day in heat and air in my sc and aside from some power loss never saw my car modes switch out while on.
thanks that is great insight
 

Mreza321

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thanks for all the great responses and insights. I have it booked at the dealer for next week so let's see what happens:)
 

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Expect your car to be at the dealer for several hours to bleed.

This thread has some pics of the bleed tool used by a dealer to bleed the system. If you look at the reservoir pics the max amount of air should be 2 quarter coin size worth, but I have been successful with about 4 to 6 quarter size air bubbles at the top of the reservoir.


If they try to bleed it without the tool in that thread, you will NOT get all the air out. Even with the gm tool, its quite time consuming and may still leave air trapped in the top of the intercooler bricks. The car must be tilted enough for the fill port to become the highest point in the system then vacuum bled. Tilted up is basically the exhaust pipes mere inches from touching the ground.
 

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