Cylinder Deactivation - Should we be thankful???

Should we be thankful the 996 does not offer cylinder deactivation. With all the (rightfully so) concerns about the IMS, Bore Scoring, AOS, etc., as potential catastrophic failure points of our engines, at least we do not have to add cylinder deactivation to the list of concerns. Personally, I owned an 08 Yukon Denali XL where the engine was on its way out at 100k because of cylinder deactivation. No recourse. Just learned of a buddy with a newer Honda Pilot that needs an engine rebuild at 112k due to cylinder deactivation. He also has a newer GMC truck with lifter issues caused by cylinder deactivation. I�m sure many of you are well aware of the mechanics behind cylinder deactivation. I am not. But, I have read on Driven motor oil website that 70% of engine wear occurs at startup. Is it reasonable to assume when the cylinders reactivate it�s similar to a cold start??? If so, it makes sense to me why these engines tend to only offer 100k life span - for the sake of better fuel economy. Also a convenient planned obsolescence strategy, if true. Thoughts???

Brian, are you more referring to the start-stop technology, where the stupid engine shuts off at stop lights and restarts when you press on the accelerator? My wife's 2017 Chevy 1500 (V8) pick up has cylinder deactivation when cruising at highway speeds. It is so smooth we don't ever feel it when driving. I am sure the injectors for those cylinders are shut off so raw fuel is not pouring down there. Start-stop is a whole other issue. A friend of mine is a mechanic at a Toyota dealership. He said they replace a ton of starters on cars with that feature. I've driven loaner cars with that technology. I can't stand the shutter or brief hesitation of the engine when accelerating from a stop sign or stop light. When it is time to retire my daily driver I'll make sure to find a way to permanently disable the "feature".

I think that technology was not widely adapted or maybe even available when 996 was new. Please someone correct me if I'm wrong. FWIW, the new GT4 has cylinder deactivation and probably auto start/stop too. I agree it's a stupid and annoying feature. Somewhat ironically, the first time I've had experience with it was when I rented a 991 Carrera S via Turo and had the car shut off on me at every light. It was a PDK too! I promptly turned that off for the remainder of the day.

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you�re right. I realize I�m talking about two different technologies wrapped into one topic. My 08 Denali would shut off 4 cylinders at highway speed. The complete shut down at stop is different. Seems both technologies lead to premature mechanical issues. Wonder if one is worse than the other?

I hate the "stop/start" technology ! As a dealer technician and a drivabilty/tune-up specialist I was responsible for decades in avoiding such undesirable events from happening..It even bothers me when a car sitting next to me at a red-light quits running and then restarts while sitting at the light...lol

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haha! Great point!

I appreciate you gents giving me a reason to not buy a start/stop car beyond my own loathing. My wife thinks I'm neurotic enough, evidence certainly helps my case!

My MB has the stop/start feature. It also has a defeat button on the dash, all I have to do is remember to shut it off every time I start the car.

The deactivation button is key....all the Euro rental cars I drive make me insane with that auto stop/start feature, but I was sure grateful for hill assist on manual transmissions when it came out, lol. I have a Chevy Silverado with the cylinder deactivation...I have not heard of any issues from anyone I know that has a similar Chevy V-8. fingers crossed. Saves a fair amount of fuel...my mixed driving MPG isn't much worse than my G37.

Absolutely.. Cylinder deactivation sucks. The simpler machine is the winner. This is why the 996 has seen a huge increase in desirability over the last few years. What isn’t there, doesn’t break.

So both start/stop and deactivation is put in the cars for EPA mileage. EPA measure car mileage in its default mode after you start the car. Manufacturers want to get the best fleet average they can but still have consumers get the perfromance they want. THis is why cars have an optional button to supress these features. In one of my cars, the deactivation is driven by what mode it is in. In Strada, its on and the car always starts in the mode that has deactivation. Frankly it is a boring mode and I immediately switch it over to sport or corsa and then there is no deactivation. At the end of the day, this was just a loophole for manufacturers to get good EPA readings and have the nuts still have the performance that attracts them to the cars in the first place.