Cylinder de-activation

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Mar 11, 2011 | 12:19 PM

#16

Cherryokee

CF Veteran

Joined: May 2010

Posts: 1,175

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From: Boston

Year: 2000

Engine: 4.7L

Quote:

Originally Posted by dilljeepo

Apart from reprogramming ECM, could you do it yourself with toggle switches inside your cabin? One toggle switch for every cylinder's spark plug and injector? That way you could turn some off and others on intermittently, or just have two toggle switches, one that turns off two cylinders and the other turns off a different two, and only have one on at once?

Also that way you could have 6 cylinders for take-off and when your on the highway you could turn off two (or even three if that's possible) from inside, and turn them all back on when you get into the city. I agree that this could be a potential temporary problem solver for people who want to combat gas prices in a gas guzzling machine

OMG! That'd be as bad, or worse, than texting while driving. You could crash the Jeep or grenade your motor!

Mar 11, 2011 | 12:27 PM

#17

dilljeepo

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Joined: Aug 2010

Posts: 320

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From: Calgary, Alberta

Year: 1996

Model: Cherokee (XJ)

Engine: 4.0L

Quote:

Originally Posted by Cherryokee

OMG! That'd be as bad, or worse, than texting while driving. You could crash the Jeep or grenade your motor!

two switches? I wouldn't be toggling them constantly, maybe one switch every hour of highway driving

Mar 11, 2011 | 12:28 PM

#18

Cherryokee

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Joined: May 2010

Posts: 1,175

Likes: 31

From: Boston

Year: 2000

Engine: 4.7L

Quote:

Originally Posted by dilljeepo

If all it takes is a new smarter ECM, why isn't anyone doing this?

Good question. I'm sure an answer lies in simple economics of scale. Maybe the development cost outweighs the potential profits...

Has anyone out there actually hacked the ECM code successfully and downloaded it for review/edit. I'm no programming wunderkind but I think it would be do-able to write/edit the necessary variables and contingency statements into the ignition control code-flow. The next phase would be to burn a new set of chips and do some prototype/trial runs. Maybe we should start a new thread and form a collaboration effort...

Mar 11, 2011 | 12:31 PM

#19

Cherryokee

CF Veteran

Joined: May 2010

Posts: 1,175

Likes: 31

From: Boston

Year: 2000

Engine: 4.7L

Quote:

Originally Posted by dilljeepo

two switches? I wouldn't be toggling them constantly, maybe one switch every hour of highway driving

Nah. I think an hour would be too long. You're still thinking of a fixed on/off set and that'll lead to trouble. I won't try to stop you - only advise you. It is your engine after-all...

Mar 11, 2011 | 12:31 PM

#20

dilljeepo

Thread Starter

Seasoned Member

Joined: Aug 2010

Posts: 320

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From: Calgary, Alberta

Year: 1996

Model: Cherokee (XJ)

Engine: 4.0L

Quote:

Originally Posted by Cherryokee

Man I've only taken one computer science course in school and it was writing computer code in Python script.... I doubt ECM's use python lol

Mar 11, 2011 | 12:32 PM

#21

dilljeepo

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Posts: 320

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From: Calgary, Alberta

Year: 1996

Model: Cherokee (XJ)

Engine: 4.0L

Quote:

Originally Posted by Cherryokee

Nah. I think an hour would be too long. You're still thinking of a fixed on/off set and that'll lead to trouble. I won't try to stop you - only advise you. It is your engine after-all...

I don't want to try it, I want someone ELSE to try it and tell ME how it goes LOL. I'm not going to experiment on a vehicle I just bought

Mar 11, 2011 | 12:35 PM

#22

2Evil4U

Senior Member

Joined: Jun 2010

Posts: 849

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From: Slaughter, LA

Year: 1997

Model: Cherokee

Engine: 4.0L

It's not as simple as turning off the fuel and spark. Although that may provide minimal improvement.

The Dodge system uses remarkably intricate lifters that latch and unlatch in order that the valves can remain seated. (If they fail, it's about $3000 to replace the system. My buddy's magnum crapped out after about 60k miles.)

In theory, the best way to do this is to use a splined connecting rod that would allow the piston to stop and eliminate all of the parasitic loss from the cylinder drag. But then, how do you control that?

Mar 11, 2011 | 12:38 PM

#23

Cherryokee

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Joined: May 2010

Posts: 1,175

Likes: 31

From: Boston

Year: 2000

Engine: 4.7L

Quote:

Originally Posted by dilljeepo

I don't want to try it, I want someone ELSE to try it and tell ME how it goes LOL. I'm not going to experiment on a vehicle I just bought

Oh Crap. I guess reverse psychology doesn't work with you! LMAO!!!

I'm not going to sacrifice my mill either...

Mar 11, 2011 | 01:09 PM

#24

ajk2005

Member

Joined: Mar 2010

Posts: 123

Likes: 1

From: Flora Illinois

Year: 1996

Model: Grand Cherokee

Engine: 318ci 5.2l

Quote:

Originally Posted by Cherryokee

Oh Crap. I guess reverse psychology doesn't work with you! LMAO!!!

I'm not going to sacrifice my mill either...

I think what you need is a 2 peice crankshaft... That way when you shut the 2/3 cylinders off they don't cause drag. I remember reading that's how some of the engines work when they shut off cylinders

Mar 11, 2011 | 01:45 PM

#25

Fanmanj

Junior Member

Joined: Aug 2010

Posts: 33

Likes: 0

Model: Cherokee

IMHO it would cause really strange problems. Your computer would detect random
Misfires all of the time, I imagine disconnecting injectors for long terms would burn out the injector drivers in the ECU. The GM/ Chrysler systems automatically open the throttle more when the engine drops to 4 cylinder mode to eliminate a power loss.
In other words, not worth all the trouble to POSSIBLY gain 1-2 mpg.

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