corvettelvr73

In class today a friend and I thought about how he could get better gas mileage in his 5.9L Durango on the way to the mountains today (3hr trip). If you were to disconnect every other fuel injector and that supporting sparkplug wire according to the firing order would this be safe. Then reconnect them when you are off the highway? Do you think this would be a huge difference? He averages 11.7 mpg now.

TDiddy

Aren't there new engines that do this automatically? I saw a blurb on the Today show (I think) one morning, they were doing a bit on the new gens of hybrid cars. This was a technology they talked about.

X-AWDriver

If you disable any injector or plug wire your vehicle will run like crap if at all.

MTL_4runner

It's a nice idea but I'm afraid that would give him even worse gas mileage.
In order to improve his mileage he could try running all Amsoil fluids (engine, tranny, diffs, etc), he can make sure the engine is properly tuned and replace all consumable parts (air and fuel filters, bosch plugs, etc) but finally he needs to modify his driving style to maximize fuel economy in that truck. This includes maintaining momentum up hills (ie speed up before you hit them, then ease off the gas and allow the truck to lose speed on the way up). It is not as fun to drive that way but your wallet will thank you.

I also recommend my auterra OBD reader which you can find in my signature. If you have a palm PDA, you just hook it up for real-time readouts while driving and one of the functions is MPG.......looks like this:



Then you just keep the pedal where you are getting the best highway mileage.

ROMAD

FWIW - Back in the late 70's someone did make a kit that would do a very similar thing to a 350 Chevy V8. It turned it into a 4 banger by using a different ignition cap and I think a 2bbl carb to replace the 4bbl.

Never saw a whole lot of those get installed but I have seen them before. I think for the same amount of money and effort you could convert over to propane at the time and be able to switch between gas and propane **almost** 'on the fly' IIRC it took just a few mins to go back and forth...

skshepherd

how much did you pay for your obd scan software? looks like you have to pay $289 plus the cost of a handheld? Nice but seems expensive. Any other similar alternatives?

TDiddy

Romad, yep they mentioned that as well, its probably what led them to it. Dodge is offering this in the new Magnum. They call it Multi-Displacement technology.

"Available on Magnum RT's 5.7-liter Hemi® V8, the Multiple-Displacement System (MDS) is a pure stroke of genius. By switching from eight to four cylinders during cruising and light acceleration, MDS improves fuel economy from 5 to 20 percent depending on driving habits."

Also see this:

http://comnet.chrysler.com/comnet/Co...contentId=2227

mt_goat

I want a hybrid truck. I read in Consumer Reports that Toyota Highlanders are now coming out with a hybrid/3.3L V6. Got me thinking about a swap, someone figure it out for me.

My99

Yes, unfortunately manually taking out spark plugs and injectors will not make the truck get better fuel economy. The truck still thinks it's a V8, and so the computer is freaking out not understanding what's going on with 1/2 the engine. The engine would run like crap, probably smoke a lot, and get even worse gas mileage. 11mpg is terrible, I hope this is in the mountains. With a 5.9, I wouldn't expect stellar gas mileage though. I think mercedes has the technlology to run on just 1/2 the cylinders in their V8's and V12's. And I know Frod had some sort of "limp mode" in their expeditions where they'd run on 4 cylinders in case of engine failure. Luckily with Toyota's, there's never a need for that right?

If he can't bite the bullet and pay the high gas prices, instead of trying to turn his big V8 into something it's not, he could consider selling and going for something that better fits the need.

mt_goat

The Honda Accord hybrid uses variable cylinder management (VCM). VCM uses 6 cylinders when accelerating, but only 3 when cruising.

midiwall

(Hey Jamie! Here we go again!)

There are a number of OBD-II readers on the market. Jamie and I both have the Auterra box (and I also have another) and they're great. Here's a quick run-down of a couple that I personally own or have used:

• Auterra - http://www.auterraweb.com
  This is the unit that I carry on the trails with me. It also sets up for use as a dynometer. Requires a PalmOS based machine to work.
  
  They're on eBay a LOT - they're new, just for less than you'd pay direct. Here's a search link for eBay.
  
  
• OBDDiagnostics - http://obddiagnostics.com
  I have this unit as well. You'll need a Windows based machine to run the software. These are only sold direct.
  
  
• OBD-2 - http://www.obd-2.com/
  A forum member has this unit and I've seen it/used it. Again you'll need a Windows box along with it, and they're also only sold direct.

corvettelvr73

Is there anything like this for an OBD I car that we can use to custom tailor certain things with a laptop?

Highland Runner

"the Multiple-Displacement System (MDS) is a pure stroke of genius". Genius my ass. This is nothing new. Cadillac tried this with thier 4,6,8 years ago which happened to be a POS. There are others like it also. In fact I think someone told me most EFI Toyotas do something like this already. The only way to save gas in a Durango is to sell it and get a Toyota. My brother has a Durango with the 5.9 and his best mileage ever was like 12MPG. We took a trip one time to FL together. We both filled up near our house. Then we drove the entire length of GA (@300miles) and stopped to get gas before going into FL. We were both on E. The only difference is he used 27-28 gals and I used 17. They put a big tank in those things so people believe think they're getting good mileage. The Dodge V-8's have some of the worst gas mileage around.

MTL_4runner

Unfortnately there is nothing like that for a 2nd gen unless you do a 3.4L engine swap.
Then you will get OBD II capability.

MTL_4runner

This is too funny Mark!

Well I don't have much to add besides the fact that Bob_98SR5 just got an auterra for $160 off ebay (I consider anything under $180 is a good deal). That was a good price and the more patient you are, the better the price will be. I have seen em into the $140s and as high as $230 so you really need to pay attention to get a good deal on one.

Both units are very good and we have bantered about which is better but the bottom line is personal preference and if you prefer to use a laptop or a PDA (or maybe both). The laptop unit is cheaper ($90 I think) but for me the portability and convienence was key so the auterra is my choice.

WATRD

There's one factor that is missing in this thread. The engines that drop cylinders for economy are designed to do so. On a standard engine, dropping a cylinder will cause the heads to heat unevenly and will lead to a head gasket failure in pretty short order.

A standard engine is designed to expect a lot of things, including even heating of the heads. When they don't get what they expect, they get cranky. I took out a perfectly good engine by having a dead cylinder. It didn't heat the head evenly and eventually warped the head, resulting in a major head gasket failure.

Don't do it.

HaveBlue

Tell him to sell his Dodge and buy a Prius.

mike_d

assuming that the truck will actually run this way, it still won't work. each of the firing cylinders will have to burn (at least) twice as much gas to maintain the same speed. the best way to improve fuel milage is to keep you foot off the long skinny pedal. it's much less fun to drive that way, but it does work. in my '89 22re, i get 20-22 mpg when i drive it. when my girlfriend drives the truck, she sees 26mpg on a tank (same driving conditions). the only difference is our driving style.

also gm tried this in their cadillac 4-6-8 (or something like that). it didn't turn out very well - check it out on google.

Tubb

I agree slowing down is the key. In my case slow down 5 MPH on the interstate, shift early etc. ment 4 to 6 MPG. Tubb

SoCal4Running

The new chevy system is called Displacment on Demand "DOD". Very high-tech with lifters that "turn off" and computer controlled throttle and exhaust.