[Greg83]

Hi guys, I’m not totally sure I have a problem yet so this might be getting a little ahead of things… I recently bought a new 2023 ZL1, it’s only has 150 miles on it. Anyhow it doesn’t seem to have the power of my 2020 ZL1, it honestly feels a little more like my 2022 SS-1LE Camaro. I haven’t taken it over 4000 RPM’s until I get to at least the 500 mile break-in. Maybe it will feel better after I can drive it harder. I also remember my other ZL1 and SS-1LE would get a lot of black soot in the exhaust tips after only a few miles. After 150 miles this new ZL1 has no soot but does have some rusty looking corrosion on the inboard tip… Any thoughts??? Thanks!!
Also, If I remember correctly my supercharger gauge on my dash was reading something like NEGATIVE 10-15 PSI while I was just cruising on the highway, is that normal? And what should my max POSITIVE PSI be when accelerating?

[Nimair.ZL1]

Originally Posted by Greg83

Hi guys, I’m not totally sure I have a problem yet so this might be getting a little ahead of things… I recently bought a new 2023 ZL1, it’s only has 150 miles on it. Anyhow it doesn’t seem to have the power of my 2019 ZL1, it honestly feels a little more like my 2022 SS-1LE Camaro. I haven’t taken it over 4000 RPM’s yet until I get at least 500 mile break-in. Maybe it will feel better after I can drive it harder. I also remember my other ZL1 and SS-1LE would get a lot of black soot in the exhaust tips after only a few miles. After 150 miles this new ZL1 has no spot but a lot of rusty looking corrosion on the inside tip… Any thoughts??? Thanks!!

I would start by bleeding the supercharger system. Sometimes the blower isn't bled properly from the factory.

For reference if the system has air in it, then it the intercooler pump will shut down causing temps to rise and for the call to pull timing because the manifold air temps are too high

[Greg83]

Originally Posted by Nimair.ZL1

I would start by bleeding the supercharger system. Sometimes the blower isn't bled properly from the factory.

For reference if the system has air in it, then it the intercooler pump will shut down causing temps to rise and for the call to pull timing because the manifold air temps are too high

Thanks, I remember reading that but didn’t realize it was a potential problem for NEW cars. Will it throw a code that the dealer can see and figure out? Or can/should I do it myself? If it’s easy to do I can research it and do it myself but I also don’t want to start messing with things when it’s so new into the warranty.

[AC Promotions]

I believe the LT4 in the ZL1 and CT5-V Blackwing has programming in the ECU to limit power until you reach 500 miles. The mild corrosion could be a result of the vehicle having some type of constraint and thereby stored at the assembly plant (basically a cold start that has moisture in the tips and then just sits until the constrained item is back in stock).The DI runs cleaner than a standard port injection car and since power is limited you aren't tipping into power enrichment mode where a lack of wideband sensors would potentially cause soot.

[Greg83]

Originally Posted by AC Promotions

I believe the LT4 in the ZL1 and CT5-V Blackwing has programming in the ECU to limit power until you reach 500 miles. The mild corrosion could be a result of the vehicle having some type of constraint and thereby stored at the assembly plant (basically a cold start that has moisture in the tips and then just sits until the constrained item is back in stock).The DI runs cleaner than a standard port injection car and since power is limited you aren't tipping into power enrichment mode where a lack of wideband sensors would potentially cause soot.

I considered the detuned ECU but I thought that was only the C8 Vett. I guess I’ll have to look into that further. Thank you!

[Vigilante375]

Yes, this can happen on a new vehicle. When the 5th gen ZL1 came out, there were cars that had 0 supercharger coolant in them.

I'd do as mentioned with the bleeding but I would also wait until you break the engine in and car actually feel the power band to see how it really feels.

Originally Posted by AC Promotions

I believe the LT4 in the ZL1 and CT5-V Blackwing has programming in the ECU to limit power until you reach 500 miles. The mild corrosion could be a result of the vehicle having some type of constraint and thereby stored at the assembly plant (basically a cold start that has moisture in the tips and then just sits until the constrained item is back in stock).The DI runs cleaner than a standard port injection car and since power is limited you aren't tipping into power enrichment mode where a lack of wideband sensors would potentially cause soot.

ZL1s have never had a power restriction until it reached a certain mileage. Only the C8 and CT5 Blackwing have that. Possibly the Escalade V and CT4 Blackwing as well.

[ShockingZ]

Burp the IC system. Thats is.

[FrostZ]

The above comments are all great suggestions, there also have been several people that have found the factory or dealer only put in 91 or poor quality gas that severely messed with the fuel trims. If you have good quality 93 in your area get a full tank and pull the battery negative cable for a bit to reset the ECU fuel trims.

[JBones81]

Originally Posted by FrostZ

The above comments are all great suggestions, there also have been several people that have found the factory or dealer only put in 91 or poor quality gas that severely messed with the fuel trims. If you have good quality 93 in your area get a full tank and pull the battery negative cable for a bit to reset the ECU fuel trims.

Oh man. All we have out here is 91

[Idaho2018GTPremium]

Some misinformation in these responses. First, the ZL1 doesn’t limit power below 500 miles. 2nd, the comment about “being in the power band” is inaccurate as well. The LT4 makes peak torque below 4K rpm, and in a given gear, THAT is what you feel. So it should feel strong at 3500 rpm in 3rd gear, for example. In 3rd gear the car pulls harder at 3600-4000 rpm than it does at 6000 rpm. So if it feels like an SS, something isn’t right. I second (or third?) the s/c coolant air bleed. It’s pretty easy to do on your own and can be done at home, and you don’t need a custom tool like some will claim. Or you could risk it at the dealer. Make sure the engine coolant reservoir is full as well.

3rd: the LT4 runs fine on 91, not ideal, but it still makes a lot of torque. That’s all there is in a huge part of the country.

[Greg83]

Thanks for all the great advice guys!!! I’m trying to run this tank low and then I will fill with 93. I will definitely look into bleeding the super charger. Worst case I’ll have the dealer look at it when it goes in for its first free oil change. I know… I don’t like them changing my oil either, and I usually do it myself but a free oil change is always nice, and they can look into my problem too. I also understand they are basically parts replacers and can often only fix things if a code shows up.

[Greg83]

Hey guys, I just added this to my initial post… If I remember correctly my supercharger gauge was reading something like NEGATIVE 10-15 PSI while I was cruising down the highway, is that normal? And what should my max positive PSI be when accelerating?

[arpad_m]

Originally Posted by Greg83

Hey guys, I just added this to my initial post… If I remember correctly my supercharger gauge was reading something like NEGATIVE 10-15 PSI while I was cruising down the highway, is that normal? And what should my max positive PSI be when accelerating?

"Negative" pressure is (partial) vacuum, this is normal while the car is running with the supercharger bypassed (for fuel economy), the pistons create a vacuum that then helps suck in air via the intake, this is how all naturally aspirated engines work. Once the supercharger kicks in (when you give it some gas), it will immediately build boost, and on your LT4 you should see 9.7 to 10.2 psi.

Bleeding the intercooler circuit is a no brainer, make sure you get it done, as others already stated above. Unfortunately GM did not add a supercharger coolant tank from the factory, so you're at the mercy of whoever assembled the engine and filled the fluids to have done it properly, the only way you as an owner could check is opening up the S/C coolant loop.

I'd say let the dealer do it under warranty, and you make sure they know what they're doing, don't hesitate to go to a different service department if you see anything suspicious.

[FrostZ]

arpad_m hit the head on the nail, LT4 blower has a vacuum bypass on the blower that is open at idle and cruising as soon as you lean into the blower creates boost closing the bypass and allowing boost to ramp up. Max boost I see is 9-10 maybe 11 PSI depending how dense the air is but that's based on the rather simple gauge.