It's happening right now! (fuel injector disconnection experiment)

[bandit86]

95 land rover discovery, 5% taller tire. 3.9Lv8 My last tank averaged 17.3L or 13mpg mixed. Went home and disconnected 4 fuel injectors and both oxygen sensors. Going for test drive. Gutless at low rpm. Sounds like a Pontiac sunfire with a fart cannon. On the highway it is not bad as long as over 2000 rpm, Then have torque and feels almost normal. I don't think the catalytic converters will like the extra air but my fuel bill for last month was 400 dollars.

30 miles so far, seems better the faster I go, over 65 and 2200rpm I can release throttle some. Will take highway with less hills home, should be 110 miles round trip

For those interested my mpg improved from 12.5 to 17after using diesel as octane booster

[bandit86]

65 mph. Third gear on the floor it has barely noticeable acceleration. Put into od and with 1/4 throttle I'm cruising at 68 @2350 rpm

I wish for my scan gauge but this too old. Have an mpguino, need to install it

[bandit86]

I forgot, there was a 25 mph winds with 40 mph wind gusts blowing in my direction of travel. It really really messed up my numbers, will do another one again. the tank of A-B-A was 105 miles, plus 15 miles on all 8 cylinders. Going with the wind the truck drove alright, going into the wind it was dangerously slow, I could not get past 60ph no matter what I tried, even rolling onto the highway was painfully slow, borderline dangerous: I need to have a switch to have all cylinders available on demand.

Most of the return trip was done in 3rd gear, engine close to 3000 rpm, a bit much for a v8. On the last half of the return trip I got off the freeway and drove some back roads, at 55 I needed significantly less throttle to maintain speed.

I noticed a similar phenomena on my jeep when I had the scan gauge plugged in, as I posted this on another forum:

I have been monitoring the 4.0 for about 6000 km with my scan gauge II. Well worth it. You can actually monitor the engine real time, all the sensors 4 at a time and fuel economy. The jeep has a funny quirk I noticed when monitoring the throttle position and fuel economy. At set throttle pressure the jeep will hit rpm humps that it cannot climb over without slight throttle increase, but will yield unproportional rpm increase. For example, at 105 on the clock, 100 actual speed at 17 units of throttle the jeep cannot accelerate and will cruise at 19mpg. If I increase throttle speed increase but mileage stays steady. However if I decelearate slightly mileage jumps up 1-2 mpg. I noticed 3 of these rpm humps at highway driving, as if the jeep lacks the torque to accelerate but at little more rpm on a different part of the torque curve if descending into it. Make sense?

Best explanation I can give is like lifting weights. Takes less power to hold than to lift. If faster speed is used to lift more weight can be lifted. Less work to quickly lift a weight and lower to set height than to lift up to that

This effect was very noticeable with the v8 running on 4 cylinders

[Spencer Fitch]

as a land rover enthusiast, and having discussed doing thid on my last discovery. i was told not to because of uneven engine wear and of course o2 issues. but since you dont give a hoot try removing the spark plugs out of the black cylinders so you dont waste power compressing air

[bandit86]

I won't remove spark plugs, the engine would still suck and blow through that hole

I removed the injector wire for every other cylinder in the firing order not just random ones.

I also disconnected the o2 sensor so the computer will not try to take readings and rich up the mixture for the 4 running cylinders.

engines are internall balanced, I dont see why vibrations would be a problem, look at harley engines they shake, ratle and roll. compressing and not firing in a cylinder still puts a load on the crankshaft

[Spencer Fitch]

Oh god.... You WANT the engine to suck and blow through those holes. You don't want to waste energy having your 4 cyclinders have to fight to compress the dead 4 cylinders.

I never said you removed them randomly..

You disconnected the o2 sensor obviously the computer has some type of Gaul for this I'm not sure if it would run rich or lean but it wouldnt be perfect either way. If you just left them plugged in but removed from the exhaust they would obviously make it run super rich.

Now what you really should do is remove the rods so they valves are all permanently closed and remove the spark plug so you don't compress the ccylinders hen plug your o2 sensor in and the only air that would go through the engine would be the ones that are active do your o2s would read correct and youd have best effeciency.

[GRU]

I don't think that's such a good idea. you may be saving 10, 20 or even 30% on your fuel bill but can't you just buy a cheap 4 cyl car and save 60% over your current fuel bill

[bandit86]

Originally Posted by GRU

I don't think that's such a good idea. you may be saving 10, 20 or even 30% on your fuel bill but can't you just buy a cheap 4 cyl car and save 60% over your current fuel bill

I am looking for one, this is just in the meantime. Today I drove another 35 miles and decided the lack of performance is something I could not live with. So I put back two injector wires, now it,s 6/8 and runs waaay better. Sounds like the perfect combination. If I had a camaro I would experiment more. Hmm,, v8 camaro... 5spd... Interesting

[bandit86]

Second fillup was mostly city, mixed 4,6 and 8 cylinders, the mileage is still way better than city rating but nowhere near as good as 4cyk on the highway was. The truck is too gutless on the get-go, would probably be easier and better to have all 8 to get going and to cut the cylinders off as I stop accelerating. I spent half the tank running on 6cylinders, good combination of not running like crap and having decent acceleration.

[Frank Lee]

Originally Posted by Spencer Fitch

as a land rover enthusiast, and having discussed doing thid on my last discovery. i was told not to because of uneven engine wear and of course o2 issues. but since you dont give a hoot try removing the spark plugs out of the black cylinders so you dont waste power compressing air

You should read up on DoD sometime.