I hear the V4 mode harms/damages the engine. Chevy dealer mechanics mention having to change out many truck and some corvette engines because V4 messes them up.
Hi and welcome to the forum Don’t pay any attention to some of the comments from the peanut gallery , lol. .Track mode disables v4 but it’s not practical for daily use. I find that in Sport mode using manual shifting that unless you are at constant speed like on the highway v4 kicks in less frequently. Took a look and found this for whatever it’s worth…..a bit long but interesting.
The “v4 mode” on the LT2 engine refers to GM’s Active Fuel Management (AFM) system that deactivates some cylinders (turning the V8 effectively into a V4) to improve fuel economy under light loads. While this system helps save fuel, it has been associated with certain mechanical issues over time.
Specifically, the cylinder deactivation via AFM can cause:
• Lifter failure or collapse, as the lifters responsible for disabling valves may malfunction.
• Accumulation of debris, sludge, or clogged solenoids in the AFM system.
• Transmission shudder and timing issues linked to the transition between V8 and V4 firing modes.
• Noticeable vibrations or shaking when the engine runs in V4 mode, which some drivers find uncomfortable.
• Uneven wear in the four deactivated cylinders due to lack of combustion but continued oil flow.
These problems have led some Corvette and GM vehicle owners to disable or block the AFM system to avoid engine damage or rough operation, though this can slightly increase fuel consumption. Some aftermarket solutions plug into the OBD2 port to prevent AFM activation while preserving ECU integrity.
In summary, if the LT2 engine runs frequently in V4 mode (AFM active), there is a potential risk of lifter and valve train damage over time, along with drivability concerns. Disabling AFM is a known fix some owners use to mitigate long-term damage or annoyance from V4 mode operation, but this is a tradeoff against fuel economy benefits. Track mode or manual mode typically disables AFM to keep the engine running as a full V8 to prevent these issues .
There are two common ways to disable or turn off the V4 mode (Active Fuel Management, AFM) on an LT2 engine:
1. AFM Disabler Device:
• This is an electronic device that plugs into the OBD-II port under the dashboard.
• It stops the computer from activating V4 mode by blocking the AFM signals.
• It is a simple, plug-and-play solution that prevents cylinder deactivation and keeps the engine running as a full V8.
• It does not require mechanical changes but should be used only if the valvetrain is in good condition.
2. AFM Delete Kit and Tune:
• This involves physically removing or replacing the AFM components (lifters, camshaft) with non-AFM hardware.
• Requires installing a non-AFM camshaft and possibly a standard oil pump (instead of the high-volume AFM pump).
• Must be accompanied by a custom ECU tune to disable AFM in software, preventing error codes from AFM removal.
• This method is more invasive but recommended if AFM lifters start failing or for performance upgrades.
Additionally, there is a software workaround for temporary AFM disabling:
• Manually limit the highest transmission gear (e.g., hold the shifter in gear 5 instead of allowing gear 6).
• AFM usually triggers in higher gears under light load; limiting to gear 5 can prevent the engine from switching to V4 mode during low-load cruising.
• This is a free but less convenient workaround useful for city driving or towing conditions.
In summary, the easiest non-invasive method is an AFM disabler electronic plug, while a full AFM delete requires mechanical changes and ECU tuning to be reliable and error-free .
lol. Won’t let me say the other word. Reminds me of George Carlin , the seven words you can’t say on TV .