I hate V4 mode on the new chevy's.

"MountainCommand" (MountainCommand) 10/24/2013 at 12:20 • Filed to: v8

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Actually, i hate that you cant easily turn it on and off. And i have reason to believe it is the cause of the oil burning issues that affect many (if not all) of the 07+ models (hoes', burbs', rados' and more). But i cant test out my theory because there is no way that i know of to turn it off.

Think about it. All cylinders running normally create pressure in all directions. Specifically it creates pressure against the oil seeping up from the piston rings. Thus allowing for minimal oil to be lost during the combustion process.

Now when you disable 4 of those cylinders from firing, that means the pressure is no longer there. I dont know the mechanics behind how the disabled cylinders operate, because i think it could be possible there might be a suction created when a cylinder is off. That suction in turn would draw oil up from past the piston rings. if that hypothesis is correct.

When those cylinders turn back on, the oil is burnt. And this happens constantly because the v4 mode comes on pretty much any time your are not on the throttle, or at 10-20%. And it becomes noticeable when you need to get on the power. It lags. And for the average joe, youre stuck with this lag.

And that is my biggest gripe. Chevy! Why didnt you allow this option to be off! As far as i know, it requires buying a specialized obd tool, or bringing it to a tuner for them to sort out.

So does this theory hold any water? It is a fact that these v8's eat up a good amount of oil. And unless they just used very weak material for the cylinder lining/walls/sleeves (whatever), the oil is being burnt somehow.

G8GT364 > MountainCommand 10/24/2013 at 12:50

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Nevermind, I see you already listed it.

Agreed though, V4 mode sucks. I had it tuned out on my G8 because it sounded like absolute SHIT going through my aftermarket exhaust system. That and the supposed "seamless" transition was very noticeable.

MountainCommand > G8GT364 10/24/2013 at 12:56

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Yeah thats all ive found at the moment too. But i havent looked any further to see what the effect of running those tunes are with the other on board systems.

so you get oil consumption as well?

MountainCommand > G8GT364 10/24/2013 at 12:56

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f kinja dp...

G8GT364 > MountainCommand 10/24/2013 at 13:00

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No I dont, I shut that crap off after owning my car for a week haha. My car doesnt use a drop of oil. However I have heard of higher mileage G8's that didnt tune out DoD having oil consumption issues(also collapsed DoD lifters is VERY common.)

MountainCommand > G8GT364 10/24/2013 at 13:00

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that was another complain i read about alot too with the exhaust noise.

Has the oil consumption changed btw?

MountainCommand > G8GT364 10/24/2013 at 13:05

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interesting.... Now the lifters, are the failures more common in the g8's? I dont think the g8 has the same v8 as the tahoe does. However, they likely use the same internal mechanisms... I havent heard of that being an issue on the chevy forums.

But thats good to know. any symptoms for a lifters potential failure?

Yowen - not necessarily not spaghetti and meatballs > MountainCommand 10/24/2013 at 13:06

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The system has been updated for '14, perhaps it's better? I don't recall reading anything negative about it in the roadtests.

Yowen - not necessarily not spaghetti and meatballs > G8GT364 10/24/2013 at 13:07

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I've read the same thing about cylinder deactivation + after market exhaust, it's pretty much impossible not to have drone unless you build some sort of weird pipe coming off your exhaust to compensate for the resonating. Apparently you have to get the length just right.

MountainCommand > Yowen - not necessarily not spaghetti and meatballs 10/24/2013 at 13:08

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true. i should specify. 07-12 (13? maybe) whenever the last of that bodystyle was. That is the main complaint years on the chevy forums.

I havent looked to see about the new ones. For one, not enough of them have had the high mileage testing like the 07-10's do.

Still, i just want to have the simple option of on and off. Without having to void a warranty to get a tune.

Yowen - not necessarily not spaghetti and meatballs > MountainCommand 10/24/2013 at 13:12

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A lot of dealerships are OK with tunes, especially if you tell them all you'll be tuning for is the cylinder deactivation. Talk to them, you may be surprised to hear that they are OK with it. Shit as a dealership I would be happy if you were willing to eliminate a possible point of failure, haha.

G8GT364 > MountainCommand 10/24/2013 at 13:14

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The G8 has an L76 which is pretty much an LS2 with LS3 heads and intake and DoD enabled so it is different than the 5.3's in the trucks. As far as being more common in the L76 I couldnt tell you but I have heard of it happening in the 5.3's. The major symptom of a collapsed lifter is a ticking noise at start up that lasts longer than 5-10 seconds.

MIKE > MountainCommand 10/24/2013 at 13:17

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Takes 1 second to turn off with tuning software. You can also mechanically lock it out too.

And yes it has been proven V4 kills lifters.

MountainCommand > Yowen - not necessarily not spaghetti and meatballs 10/24/2013 at 13:18

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Well my familys tahoe isnt under the warranty anymore, but i guess i meant that generically speaking.

I thought they would be mad because they want you back in to fix problems in your car you never had, haha.

Yowen - not necessarily not spaghetti and meatballs > MountainCommand 10/24/2013 at 13:34

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haha I guess so. It's just that I've heard several stories of dealers being ok with tunes, but for everyone of those there is one that doesn't like it, haha.

Arandomvirus > MountainCommand 10/24/2013 at 13:37

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I'm not familiar with the workings, but I doubt it absolutely closes off the cylider like you think. the valves probably open and close, so the pressure escapes. ( 1 pc camshafts)
It makes more sense to just shut off fuel and maybe spark.

lepie > MountainCommand 10/24/2013 at 13:43

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All you need to do is trip a fault code. Pull one of the leads to an injector and start the car. It will trip a fault code. Turn it off, reconnect the lead and drive off. The fault code will reset after three full heat cycles.

FJ80WaitinForaLSV8 > MountainCommand 10/24/2013 at 13:45

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I believe the reason you cannot disable cylinder deactivation has to do with federal regulations. In order to get certain government prescribed CAFE mileage ratings they obviously need to use cylinder deactivation. Having the option to deactivate it would increase fuel consumption which the government doesn't want you to do.

Its similar to the shift lockout on manual tranny Corvettes and other sports cars close to getting slapped with the gas guzzler tax.

fink stinger > MountainCommand 10/24/2013 at 13:49

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Having had 2 Gen3 engines without V4 mode and currently have 2 Gen4 engines with V4 mode, I can say that they all burn plenty of oil. None as much as the Northstar, but plenty more than any LT1, 4.3, 2.8 or 3800 I have owned.

ATX211 > MountainCommand 10/24/2013 at 16:14

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I didn't have an 07-13 Chevy truck, but I did have Dodge's Hemi in a Charger R/T and the AFM was terrible.

Recently though I did buy one of the 14 Silverados with the Direct injection 5.3 with AFM and it is the most seamless I have been in yet. I notice everything when I am driving, and I have not been able to pick up on it yet. I don't know how improved it is over previous Chevy motors, but it kills every other AFM system I have driven with.

MountainCommand > ATX211 10/24/2013 at 20:24

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good to hear they have got the lag down. I havent gone searching to see how well the new models have fared with this system.

How do you like the silverado in general?

ATX211 > MountainCommand 10/24/2013 at 20:40

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Love is a better word. It has been pretty spectacular so far.

Manuél Ferrari > MountainCommand 10/24/2013 at 23:46

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Don't make me sad! I've never owned a car with cylinder deactivation, but I was hoping it was the future. I'd much rather have a N/A engine that shuts down half the cylinders than a car with forced induction. CAFE is forcing car companies to use either turbo charging or cylinder deactivation for their mainline cars, and I'd much rather have N/A sound and revs.

MountainCommand > Manuél Ferrari 10/25/2013 at 10:23

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well if you get one of the newest models, maybe theyve sorted out some issues. But for exhaust note complaints, theres no compensation for sound when you take away 4 cylinders.

Id rather not have any CAFE standards as they are a joke. But i wont go on about that haha.

Manuél Ferrari > MountainCommand 10/25/2013 at 12:27

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True it won't sound good when running on 50% of the cylinders. But that's taken care of by mashing the throttle :)

I wonder what direction some of the N/A stalwarts will go in. Porsche has kept the base 911 models N/A and reserves the turbo for the high end. Most of their cars that are intended for the track have been N/A. Will the Carrera S have a smaller turbo charged engine in the future, or will they keep it between 3.4 - 3.8L and use cylinder deactivation? I hope the later. But I wonder if cylinder deactivation is even possible with a flat 6...

MountainCommand > Manuél Ferrari 10/25/2013 at 12:43

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holy balls. sory i cant post my response for some reason.... hang on..

MountainCommand > Manuél Ferrari 10/25/2013 at 12:50

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6 cylinder deactivation is entirely possible without a doubt. But reliability is probably the main concern. Plus Porsche doesnt have to go by CAFE standards, thought they have to follow the EU stuff. But i dont believe in cylinder deactivation at all.

The real future is what koenigsegg is doing.

"Free Valve technology that does not require a camshaft to run"

Computer controlled individual valve operation. Brilliant! This is seriously some real impressive technology. V4 mode will be put to shame when this comes out.

Manuél Ferrari > MountainCommand 10/25/2013 at 12:58

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Sorry I assumed Porsche had to follow CAFE rules to sell cars in the US. But yeah if not CAFE then the Euro version of it, whatever it is called.

This Koenigsegg tech is interesting. I wonder if they have a patent on it. If so they'll probably license the tech to other companies as that would be a great way to generate revenue to build supercars with.

MountainCommand > Manuél Ferrari 10/25/2013 at 13:40

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Hmmm. You had me second guess myself. so i went on a searching spree. Turns out its nearly impossible to find the answer i was looking for and have to draw conclusions.

Technically, no one has to follow the CAFE standards. They just pay a fine: "If the average fuel economy of a manufacturer's annual fleet of vehicle production falls below the defined standard, the manufacturer must pay a penalty , currently $5.50 USD per 0.1 mpg under the standard, multiplied by the manufacturer's total production for the U.S. domestic market."

But you may also be right. It seems that this standard does apply to all cars sold in the US. Maybe not just produced here. But what im confused about is why arent we hearing anything about this from ferrari, lamboghini, lotus, etc etc. I really never found the answer to my question. "do foreign produced cars have to abide by CAFE standards". Maybe the short answer is yes, long answer no. Unless since the new CAFE standards come out for the 2017+ models, thats when it will apply to foreign stuff?

They really make it hard to find info on this stuff...

Im sure they have to have a patent on it. They put it up on the internet for all to see. And they are working with that other company they mentioned in the video. I just want to be able to invest in their stocks.

MountainCommand > Manuél Ferrari 10/25/2013 at 13:47

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okay more searching found this:

http://forums.corvetteforum.com/off-topic/2444…

Of course there are always exemptions to the law...

Sounds like MB and BMW pay the fines. Porshe is excempt, along with all the other sports/super car manf.

Manuél Ferrari > MountainCommand 10/25/2013 at 14:20

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Interesting. I will read that thread. Would be pretty cool if lower-volume sports/supercar manf are exempt.

Only problem is that Porsche is starting to sell so many SUVs that they could become a high enough volume seller to lose exemption.

MountainCommand > Manuél Ferrari 10/25/2013 at 22:17

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Think again. VW owns them as far as i know... and vw can surely maintain high mpgs anyways.

http://www.autoblog.com/2012/07/05/vol…

Manuél Ferrari > MountainCommand 10/26/2013 at 04:16

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True if it goes by the parent company's overall fleet MPG and not the indivual brand's average then that's a good thing for Porsche. Lots of VW Golfs and Polos out there