2022 ZL1's using manual bypass control from factory

[TriPinTaZ]

Tuning a 2022 ZL1 and everything is OK with a few weird differences in logic with Flex Fuel. BUT, the new surprise is that the bypass valve is no longer electronically controlled. It is literally only a vacuum line on either side of the valve. So changing the tune does nothing to allow more boost. The car has an 18% overdrive and its getting up to about 14.5 psi and then flutters and I think the bypass is actually opening and bleeding boost. Anyone have any experience with the 2022 blower changes?

Right now were going to test reducing the pulley to 10% overdrive to see if the pressure stabilizes.


New logic in the 2022's with Flex Fuel, it seems that as long as the VIRTUAL logic detects 19% or less percent of ethanol, the ECU still references the gasoline tables regardless of what the Alcohol is displaying from the physical sensor.

[sevinn]

I'd be curious to see the stock tune file if you wouldn't mind sharing. No experience with this yet though.


Interestingly enough the service manual has instructions for changing the electronic piece, but I think it's a relic based on reading the description and operation section and looking at some pics online. Weird.

msedge_6tD82sftja.png

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[Higgs Boson]

The tune for a 22 has no tables in it for the bypass valve, at least if there are they aren't defined in the one I have.

[TriPinTaZ]

I'd be curious to see the stock tune file if you wouldn't mind sharing. No experience with this yet though.


Interestingly enough the service manual has instructions for changing the electronic piece, but I think it's a relic based on reading the description and operation section and looking at some pics online. Weird.

msedge_6tD82sftja.png

msedge_yi3IJsiux7.png

Here ya go.

2022 ZL1.hpt

Yes the 2022 is missing some tables in regards to the bypass control. I wonder if there will be someone that makes an aftermarket bpv. The 2022 has no electrical connections at all. See below for a picture of the 2022 ZL1.

2022zl1bpv2.jpg

[sevinn]

Guess the only thing that can close it is vacuum then. Maybe move bypass to a different port? But then that would affect part throttle operation maybe.

[TriPinTaZ]

So then maybe it is like the older stuff where it either bypasses to lower pressure(in vacuum) and closes when you open the throttle. I wonder if it can't hold closed though past a certain pressure. It sure flutters a lot more than I'm used to seeing on earlier cars with an 18% pulley.

[cadillactech]

Would a stiffer spring the in bypass actuator help hold the valve closed with increased boost pressure?

[sevinn]

Has to be something we can do. Wonder why this isn't an issue with older setups or swaps? Did the vacuum hose routing change on the valve?

[Higgs Boson]

seems like vacuum would open it rather than keep it closed.

just will come down to how much boost it can hold without leaking as it appears the ecm will no longer open it to bleed pressure/power.

just another result of the chip shortage, lol.

[sevinn]

seems like vacuum would open it rather than keep it closed.

just will come down to how much boost it can hold without leaking as it appears the ecm will no longer open it to bleed pressure/power.

just another result of the chip shortage, lol.

Yeah, it sure is interesting. I've certainly had other lt4s to 18-20psi holding no problem. Maybe his customer just got a weak valve.

[TriPinTaZ]

seems like vacuum would open it rather than keep it closed.

just will come down to how much boost it can hold without leaking as it appears the ecm will no longer open it to bleed pressure/power.

just another result of the chip shortage, lol.

That is what I am wondering. Maybe there is a spring in there now that limits boost....maybe not.

Yeah, it sure is interesting. I've certainly had other lt4s to 18-20psi holding no problem. Maybe his customer just got a weak valve.

The pre 2022's had more vacuum connections and a sensor or controller attached. TBH I never really paid much attention to it until now.

[sevinn]

Yeah I've deleted alot of solenoids to make sure they weren't causing issues. Technically should just be setup like these are now I guess

[TriPinTaZ]

We are still going to pulley down. The owner installed an 18% overdrive on an unported blower. I don't think that its very beneficial to pulley past 10% without porting. It is possible there is just a lot of turbulence. It is getting to 14-14.5 lbs of boost.

[sevinn]

Just curious what you found here

[TriPinTaZ]

Car just ran a 5.9 60-130 draggy so its still fast. However, the owner hasn't swapped pullies yet to lower the boost. Essentially, the car hits 14ish PSI and flutters a lot. I haven't found anything new as the shop I work with says the owner hasn't come back yet as planned. My current theory is that GM is regulating boost manually somehow, maybe a spring inside? And it keeps cracking open around 14PSI. If the owner doesn't swap pullies I won't know much more until we come across another 2022.

At least I learned the ECU logic on the 2022's and flex fuel is a little different. Typically when you add a FF sensor and enable it,, the ECU always uses the Flex Fuel spark and fueling tables. Additionally, it typically follows the Alcohol Sensor % PID for its adjustments. I have found that the 2022's rely on the Ethanol Content(SAE) PID which lags behind the Alcohol Sensor PID(from the FF sensor itself). And until the Ethanol Content PID reads 20% or higher, the ECU continues to use the gasoline spark and fuel tables. Just a note in case any of you guys get your hands on a 2022 ZL1 anytime soon. Otherwise everything seems to work the same with a few minor calibration changes from GM vs previous years.

[TriPinTaZ]

So we cammed this same car and are re-tuning. Strangely the throttle only opens halfway and it reports that commanded engine torque is equal to about half of what is in the driver demand table. I ran into a similar issue on a 2019 ZL1 but it was only one of the airflow tables I had forgotten to increase. This one isn't responding to any of that and it seems kind of weird. Literally tuned a cammed 2018 ZL1 the day before without an issue. Guess I have something new to figure out.

[Joshinator99]

Jason, I’m running the Smoothboost electronic boost controller on my car and it works mint. Might be worth trying if this new manual bypass gives you trouble.

[TriPinTaZ]

Thanks for the tip Josh. It seems like the car has been fine on the stock setup. Boost lowered a bit with the cam and the curve looks smooth so I wont mess with it unless the customer is concerned.

BTW, got the cammed 2022 sorted today. You cant max out the Torque airflow values like you used to be able to on earlier models. For whatever reason it causes the throttle to only go to 50.1 % no matter what. I went back and increased the values to a more reasonable amount and the half throttle issue was fixed.

[blindsquirrel]

The bypass's vacuum port is between the TB and rotors, so it only sees vacuum-to-atmospheric? What would it do if you moved the vacuum source to a location post-rotors so that it would see vacuum AND boost? Boost would assist the spring in holding it closed, right?

[lt1z350]

I have now done two of these gm is using the throttle control as the abuse valve vrs the actual valve. Hptuners scanner is also not logging boost/kpa correctly on it for some reason. Stock car I had shop take off the bypass line and cap it leaving on the vacuum side only so that it will open at idle as it should. rotofab big gulp and e70 car is making 670whp a10 1le car. Log shows it as 9.5-10 psi but its at 185 kpa peak and in florida with 14.2 baro do the math its 12.6 psi and not the 9.5 the log is showing.. I dont typically see this issue on early cars. Car is very fast has put 2 cars on a local 2020 gt500 that has a intake and 93 tune. The new blackwing is using the same blower setup and as known cant be tuned. I was curious if gm changed the upper pulley on the zl1 like the blackwing to a little smaller stock but yet to measure it. But nearly 13 psi stock is pretty good on one of these and a little higher then typicaly see.

Just looked at a log from a cooler night and it was 195 kpa peak on the log racing the gt500 and that is not ususal for one of these. I was going over dyno logs and on the dyno it was 185 kpa so maybe this one has that smaller upper like the blackwing that has a little higher hp rating from gm 668 vrs 650 I believe. Car did baselne 560whp and this dyno is known for being the heart breaker of south flordia as crushes so many kids on dyno days for what they think their ricer is making for hp. lol
Car is going to get headers are the usual mods here soon and expect it to do very well seeing what I have so far on it. 6.5 60-130 ao far is his best and its been pretty hot in south florida.
But back to topic look at the kpa I bet your higher then what psi is showing on logs. I see this all the time on the 4 cylinder turbo gm cars I tune so got used to looking at both and comparing pids as hptuners is often not correct on it.