Cylinder deactivation technology (thoughts?)

[wagslick]

I'm looking for a newer used truck. One thing I heard a little bit about was something called cylinder deactivation technology. The way I understand it is the truck only uses all cylinders when needed. When coasting and going down hill some cylinders are not used. These are things I can't verify, but things I've heard.

I was wondering if anyone knew anything else about cylinder deactivation technology like which years of silverados have CDT (Cylinder deactivation technology, or do all trucks of newer years have CDT or just some of the trucks? Is any performance lost with CDT and is it known for causing any type of problems?

[maxwedge]

You are basically correct, this is a fuel mileage issue. Google GM cylinder deactivation for the details.

[j cAT]

Originally Posted by wagslick

I'm looking for a newer used truck. One thing I heard a little bit about was something called cylinder deactivation technology. The way I understand it is the truck only uses all cylinders when needed. When coasting and going down hill some cylinders are not used. These are things I can't verify, but things I've heard.

I was wondering if anyone knew anything else about cylinder deactivation technology like which years of silverados have CDT (Cylinder deactivation technology, or do all trucks of newer years have CDT or just some of the trucks? Is any performance lost with CDT and is it known for causing any type of problems?

I know of one person who has a new silverado 2010. the non 4wd vehicle gets 23 MPG. his toyota 4wd truck 2009 gets 15mpg.

he has had no problems yet !

[kahjdh]

Im not just saying this because im a chevy guy but in my experience the dod in the gm v8's are the best so far. The ford cam phasers are garbage and need replaced around 70-80k miles. Chrysler and gm use the lifters and this works good but in chryslers case the oil passages are too small and cooks the oil clogging it. I have seen no problems soo far with the 5.3 dod motors.

[iroc343]

I have a 2007 Tahoe LTZ with the 5.3 with cylinder deactivation. It is as smooth as silk in operation, but I question the fuel mileage improvement. I get 17-18 mpg on the highway at 65-70mph. My previous vehicle was a 2003 Yukon with the 5.3 and no cylinder deactivation. It got 17-18 mpg at 65-70 mph. In my opinion, the idea sounds great, unfortunately, In my experience, the results are not there.

[j cAT]

Originally Posted by iroc343

I have a 2007 Tahoe LTZ with the 5.3 with cylinder deactivation. It is as smooth as silk in operation, but I question the fuel mileage improvement. I get 17-18 mpg on the highway at 65-70mph. My previous vehicle was a 2003 Yukon with the 5.3 and no cylinder deactivation. It got 17-18 mpg at 65-70 mph. In my opinion, the idea sounds great, unfortunately, In my experience, the results are not there.

the 17-18 MPG on the hywy is normal on all the 1500 5.3L gas engines 4X4 truck /suv . with NO de-activation engine management.

you should be up around 20 MPG

[kahjdh]

well you still have to remember these are 6500lb+ vehicles so its not going to be night and day. Although My college instructor had a hybrid silverado for the asep class and there was a noticable difference.

[slo99sierra]

GM's version is Active Fuel Management. As said they use lifters, but these lifters have a sort of solenoid...There have been a few cases where the lifter solenoids have failed, but not a common problem yet. If you don't want the AFM and don't want to dive into the work of tearing it all apart...having a tuner such as Black Bear Performance or Nelson Performance tune the AFM out.

[danielsatur]

I guess CDT, deactivates ignition timing, fuel, and compression!
A switch from V6 to V8, it demands on driver and how much HP is needed for the load at the time.

How much is the computer, if it go's bad?

[slo99sierra]

Originally Posted by danielsatur

I guess CDT, deactivates ignition timing, fuel, and compression!
A switch from V6 to V8, it demands on driver and how much HP is needed for the load at the time.

How much is the computer, if it go's bad?

GM's AFM deactivates 4 cylinders. For Chrysler I believe they deactivate 2 Cylinders at a time until it reaches 4 cylinder mode in the V8 models IIRC. I'm unfamiliar with Ford's DOD however.

[kahjdh]

dod on a 5.3 energizes a solinoid which detours oil flow form the lifters of the 4 cyclinders being shut off. They also cut the injectors and adjust timing to compensate for the lack of power strokes. Not all the complicated if you think about it. If there is a solinoid or lifter prob they are relativly easy to replace thanks to the dry intakes on these.

[danielsatur]

It sounds interesting, but I would rather use my 4-cylinder Tribute for fuel economy, and Jaguar for Horse power.

[kahjdh]

But you can have both!!!

[danielsatur]

If one go's bad, at least I got a spare!

[ukrkoz]

i drove brand spanking new Tahoe with V8 and deactivation. hwy for 95% of the trip from Seattle to bend, OR, and back.

it did what, 16 something mpg? i think, i got it from 16.7 when rented, to 16.8 when returned.

my 2000 Silverado with straight V8 does 22mpg hwy.