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Injector Cut-Out = MEGA MPG'S!!!
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Author:  kkkustom [ Tue May 09, 2006 8:46 am ]
Post subject:  Injector Cut-Out = MEGA MPG'S!!!
I did not want to put this in the Mileage forum because there is not a lot of traffic there, or the Performance forum because well this would be reducing performance! So MODS please leave this in General Discussions.

On the ride into work, just as I passed the tractor trailer and my gas light chimed in, it made me think... Could I rig up a injector cut out of some sort, that when I am at cruising speed and there is little load on the motor I could cut the fuel flow to one maybe two cylinders? I have not looked into how they do it with the V8's on full sized trucks, but in my head it cant be that hard!

What do you think?!?! can it be done?
Author:  pixeldzn [ Tue May 09, 2006 8:52 am ]
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I think you need more coffee before you start brain storming :lol:
Author:  uvalax236 [ Tue May 09, 2006 8:57 am ]
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I think your on to something. The WK's have this for their V8. It might be possible to use the PCM from the WK but have it reprogrammed for a V6. I need more coffee :shock:
Author:  MudTrac [ Tue May 09, 2006 9:26 am ]
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I don’t know if you could achieve that with out the proper engine timing advance to match this shut off. I could see very poor performance and possibly engine damage if you tired this. GM and DC have this on some of their engine but the computer monitors for the change and, closes valves and changes spark timing and all sorts of other things. With computer controlled engines I wouldnt even consider this. Something funny like this we use to do at the track is, on the staging lane turn a switch to cut one of the plugs and the engine would sound like crap, then when you stage and are lined up cut it back on a watch the fear rush back into the guys eyes next to you. LOL

uvalax236 wrote:
I think your on to something. The WK's have this for their V8. It might be possible to use the PCM from the WK but have it reprogrammed for a V6. I need more coffee :shock:

This is not just a electrical reconfigure, it also uses a very advance hydro system off the cam side of things. I don’t think this would work at all, without the proper mechanical system in place. Just my $.02

Check THIS site out for more info
Author:  kkkustom [ Tue May 09, 2006 9:51 am ]
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Well what I figure is this, when your injector clogs or completely dies... no fuel comes out, and the spark plug will spark at normal time, but there is nothing to combust. I dont see how this would "hurt" the motor. In my eyes it would be just like turning over that cyclinder as if you were completely out of gas!

Also someone mentioned they close valves... I dont see how this is physically possible becasue the valve is connected to a camshaft... but i could be wronge.

My idea is this, a switch that simply cuts the 2 wires that go to the injector. Maybe get fancey and find the type male and female connectors that are on the injector head that way you dont need to be cutting up the oem wireing any.
Author:  MudTrac [ Tue May 09, 2006 10:18 am ]
Post subject: 
kkkustom wrote:
I dont see how this is physically possible becasue the valve is connected to a camshaft


Not to start a war with you on this, but just the simple fact that you dont think this is possible might lead me to belive you dont know much more about how your injection system works. You might try looking on google for some more info on MDS engines and how they work, much less, how even a VVT engines work and how the new Charger even has teliscoping injectors, plugs and valves to prevent head contact and to turn off the cylinders.

But if your sure it wont hurt it, try it out, that would be awsome if you saved some fuel in the long run with it. Looks like you have done your research on this already. But really a 10min google search will increase your knowledge by at least 3 times on this subject. I agree that it would be nice, wish it was that simple. ~Cheers
Author:  kkkustom [ Tue May 09, 2006 10:55 am ]
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Mudtrac... I hear ya I really dont know too much on the head designs on our motors, that why i said "I could be wronge" becasue I would not doubt that there are some very complex heads out there what could dance the waltz above each cyclinder if they wanted to! not to mention I am at work, so i can hardley sneek a way to check the post! but I will look more into this at lunch.

and by the way i know your not starting a war... I dont get offended over this stuff. I know ALOT about motorsports and the like, but I dont know EVERYTHING, so it is all good!

later
Author:  SavageSS27 [ Tue May 09, 2006 11:34 am ]
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After reading this it seems like it would be possible just to cut out the injectors, and if need be cut off the spark too, then the piston is just going up and down in the cylinder like an air compressor, no harm done, the valve timing would be the same, so i don't see how you'd strike one, but then again, i have almost no experience with cars, so i could most definately be wrong.
Author:  kkkustom [ Tue May 09, 2006 11:46 am ]
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You would not want to cut the spark, i dont think... becasue if you do that is just one more thing that the ecu MIGHT see as faulty. I am willing to bet that the ECU will notice an injector or 2 down, but who know it just might send a CEL and thats it.

The MAF will be seeing the same air coming in, and the ecu will send the signal to each injector to pump the same amount of gas, and weither or not the correct amount of gas accually comes out of the injector i realy dont think the ecu will even know. also the O2 sensor will still see a stoich (correct af ratio) condition and wont think it is improperly tuned.

the only way to see is start the car, and yank an injector clip! hehe :)
Author:  Eddo [ Tue May 09, 2006 11:56 am ]
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Well I don't think cutting out a couple cylinders will harm a thing. It will probably run rough and you will get a check engine light.

However, I don't think you will get better MPGs. To maintain a certain speed you need to deliver a certain about of power to the ground. That power comes from burning fuel. You cut out the fuel to two cylinders, the other 4 need more fuel to still produce the need power to maintain speed.

One of the advantage of MDS is that when you cut out two cylinders it also keeps the valves closed. They electrically stop the flow of oil to the lifters and hence they collapse and the valves don't open or close. This cuts down on some of the pumping losses and improves mileage slightly. Each cylinder has some energy loss to compression, that is not return on the power stoke.

Now without shutting down the valves you are still going to be compressing air in each cylinder on the compression stroke, but not injecting any fuel. Hence you are getting zero return from all the energy need to compress those two inactive cylinders. So you essentially have a 4 cylinder motor, that has to still pump two cylinders. Your 4 cylinder motor now has to move your Jeep and run a 2 cylinder air pump. In the end you will probably end up with worst fuel economy. But , if you have some free time go ahead and try it and let us know.
Author:  MudTrac [ Tue May 09, 2006 12:00 pm ]
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Well best case for this would be throwing a CEL and wearing out the cylinders unevenly. Worst case you blow the head. The firing order on the 3.7 is 1-6-5-4-3-2, I would only turn off 3 and 5 to start with, infact i would test it just by pulling the spark wire for 3 and 5 and then uncliping the harness for the 3 and 5 injectors. try starting the jeep and its going to sound like crap, BUT youll be saving 20% on your fuel consumption.... If the truck starts, with in about 30 sec you should throw a CEL , but dont worry cause you know why. try running the engine up in RPMs and see what happends. any loud clanking noises and Id turn it off. Its goign to sound like its choking though, thats casue it is. Oh if anyones does this dont hold me liable for it casue I didnt make you do it and Im not saying its going to work right, it was only a guess at what might work just to turn off the fuel. Oh can you also make an audio clip for it? Im really interested now.
Author:  MudTrac [ Tue May 09, 2006 12:03 pm ]
Post subject: 
Eddo wrote:
Now without shutting down the valves you are still going to be compressing air in each cylinder on the compression stroke, but not injecting any fuel. Hence you are getting zero return from all the energy need to compress those two inactive cylinders. So you essentially have a 4 cylinder motor, that has to still pump two cylinders. Your 4 cylinder motor now has to move your Jeep and run a 2 cylinder air pump. In the end you will probably end up with worst fuel economy. But , if you have some free time go ahead and try it and let us know.


Bravo well said.
Author:  WV(0)IIIIIII(0) [ Tue May 09, 2006 12:57 pm ]
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I don't know if this will give any insight but this past weekend I changed out the plugs and left a coil unplugged by accident. Well the Jeep started and ran it sounded funny though so I pushed on the gas and it had a huge miss on that cylinder. The idle kept bouncing under a load and it gave me a check engine light that went off after I plugged the coil back up and started and ran the Jeep a couple of times. So, in conclusion I think you would probably do more harm than good.
Author:  ATXKJ [ Tue May 09, 2006 1:20 pm ]
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There are a couple of ways of cutting out the valves - I think the Hemi uses a solenoid to shut down oil flow to the hydraulic lifters on 4 cylinders, and even then they only pick up 2-3 mpg at cruise. Other folks have tried multipart camshafts that engage a second lobe. Fun toys, but mileage and reliability have yet to be proven.
Author:  kkkustom [ Tue May 09, 2006 2:00 pm ]
Post subject: 
Eddo, i see what you are saying about how I just made a 4 cylinder gas motor and a 2 cylinder air pump... did not think of that... but in my head I cant see how you could not allow a valve to not open up... because the lob on the cam hits the tappet on the rocker which on the other side pushed the valve down into the head and into the combustion chamber opening the port. the only way i can see this working is some how a servo or something has to slide the rocker arm to a side, past the lob on the cam thus not allowing the cam to move the valve. But if you could keep the intake valves closed, and the exhaust side open there would not be much resistance on the “dead” cylinder. I am looking right now for more info on this MDS you speak of! Lol.

2 nights ago, my gf's stratus POS died... somehow only the first injector on the rail is getting gas! don’t know why yet. the motor will not fire and start itself, but by blasting starter fluid in the intake it will fire all 4 cylinders, one on gas/air/and starter fluid the other 3 on just air and starter fluid! anyway once it is running somewhat under its own power, you can feel the head pipe on bank 1 is getting hot, and the other 3 are ice cold! but the beast is still turning over and runs for about 30 seconds all by it self... this give me a bit of confidence with my Jeep!
Author:  kkkustom [ Tue May 09, 2006 2:06 pm ]
Post subject: 
lol, ATXJ... I don’t know how I missed your post before I responded, but that sums up my confusion on how the valves can stay closed... thanks! and I cant see how smooth you can make the transition between 2 lobs on a spining crank shaft.. it would neeed a taper or something to allow it to "slide" back on to the lobe??? and you are right reliability would decrease with the increase of oddly moving parts at high RPM.
Author:  kkkustom [ Tue May 09, 2006 3:01 pm ]
Post subject: 
the answer to my valve deactivation questions...

Displacement on Demand also leverages an existing oil pump system to provide hydraulic pressure to activate the system. The mechanical actuators are special hydraulic lifters, each with a spring-loaded locking pin that deactivates the cylinders. In normal operation, when the camshaft rotates against the hydraulic lifter, it opens and closes either an intake or exhaust valve.

The special lifter, developed by Eaton Corp., is designed so that one section can collapse, or telescope, into the other section. The two sections can be either coupled or uncoupled to each other by means of the locking pin. When cylinder deactivation is initiated, hydraulic pressure is used to dislodge the locking pin and collapse the lifter, thus closing the valve. In reactivation mode, the removal of hydraulic pressure causes the locking pin to return to its latched position to restore the lifter's normal function.
Author:  MudTrac [ Tue May 09, 2006 3:08 pm ]
Post subject: 
The MDS I speak of is DCs term for their multi-displacement system.

Here ya go MDS LINK

Cams and Heads have come long way from a "pure" chain drivin system. Honda powered this technolgy field with their VTEC system back in the 70's. Since then Ford GM and DC have also adapted newer head design. Also I see an issue with leaving just the exhaust side open, youll get back pressure build-up in the cylinder and have dirty waist going into the cylinder. No good.

I say just leave it the way the smart guys in the engineering department at DC decided it should be. Your not going to see any improvment in MPG, I think.... Could be wrong though I guess
Author:  kkkustom [ Tue May 09, 2006 3:22 pm ]
Post subject: 
MudTrac wrote:
The MDS I speak of is DCs term for their multi-displacement system.

Here ya go MDS LINK

Cams and Heads have come long way from a "pure" chain drivin system. Honda powered this technolgy field with their VTEC system back in the 70's. Since then Ford GM and DC have also adapted newer head design. Also I see an issue with leaving just the exhaust side open, youll get back pressure build-up in the cylinder and have dirty waist going into the cylinder. No good.

I say just leave it the way the smart guys in the engineering department at DC decided it should be. Your not going to see any improvment in MPG, I think.... Could be wrong though I guess


I looked into the MDS and the DOD GM tech alot more, and have a better idea whats going on with them now. Also noted that the backpresure would force junk back into the combustion chamber too, good point.

I wish my 3.7L had VTEC and MDS... it would be awsome... lol
Author:  ChileanKJ [ Tue May 09, 2006 6:54 pm ]
Post subject: 
May be this is a very dumb question but, can i use the method of taking the injector connector out (so not fuel is injected), sparkplug out on one cylinder and use an adaptor with the spark plug thread to fill up my tires? i know it only can work on a gas motor and not my CRD, but this need to have good pressure.

Claudio
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