Disabled 4 cylinders on a TBI motor :) MPG Gain???

[jpoole]

The ecm has no Idea that you cut half the engine off. Optimization.

Right, it doesn't know I cut half of the air out just like it doesn't know I cut half of the fuel out.

 

[Jims86]

Ok....good luck with the experiment. Hope it works out for you.

 

[jpoole]

Ok....good luck with the experiment. Hope it works out for you.

Thanks...that's really all it is. My wife hates my burb. If I destroy it, she will be happy
I am looking at getting a cable now for datalogging.

 

[Christian Nelson]

NOt another square getting a torn all up? Jeeze, what part of they arne't making any more of these can't people understand???

Anyhow, back to the mpg thing, I am confident your 4 cylinder thing would have gotten you probably the same result if you'd gotten all 8 running healthy as they should on this truck. 17 is very doable with all 8 with OD on a suburban.. If you were getting 20 or something, I'd maybe think there's more to this, but you are just getting what a well tuned 8 would get, and might wreck something in the process, ending up sending yet another square to China to be melted so we can buy another hunk of crap from Walmart that will break after two uses seems like not alot of gain for the risk factor..

HRPC, sounds like you are speaking of some other truck?? I am confused..

 

[Old77]

This may be a stupid question with regards to the topic of this thread so please forgive me in advance but why go through all this work and effort to save 2 MPG as opposed to going through maybe the same effort (or probably less) to give the motor a good tune up, get her running right (on all 8 cylinders) and improve your MPG that way? I guess I just don't see the point at all.

 

[jpoole]

This may be a stupid question with regards to the topic of this thread so please forgive me in advance but why go through all this work and effort to save 2 MPG as opposed to going through maybe the same effort (or probably less) to give the motor a good tune up, get her running right (on all 8 cylinders) and improve your MPG that way? I guess I just don't see the point at all.

That's a good point however my motor was properly tuned already(new plugs, wires, cap and rotor, etc and timing was correct. 13.5 is what I consistently got on my commute. I have gotten 17 before on highway driving with all 8. I had a 3+ mpg improvement on my commuting so I will get my $4 back on my expansion plug pretty quick The point for me is I thought about the idea then implemented it and gained some knowledge in the process.

 

[Jims86]

Yep, this thread will get cleaned up. Got off topic with Jim's Burb. My fault !!! Get a few minutes, I'll transfer that convo to the Off-Topic thread or Burb for sale thread. Is it donated yet Jim? I sure hope not.

Not yet...paperwork is on its way for me to fill out though.
I agree with that Old77 yahoo, a good running V8 can creep even closer to 19 mpg, and thats 4 wd...a guy called EagleMark on the EFI forums owns it.
Its a lot of work, but this 4 cyl thing could work, but only with a tune, and definately a gearing change in the rear end.

 

[GreaseDog]

I agree with this statement, although I wouldn't necessarily call hp an imaginary #. It's a real #, but its a calculated # based off of torque and rpm.

As Carroll Shelby quotes, Horsepower sells cars, Torque wins races.

And who says Mr. E Ferrari said this too? I hate seeing quotes on the internet that are wrong.

It's an imaginary number. You cannot accurately measure horsepower by itself. Anything that measures horsepower actually measures torque, and then inserts it into the equation... Horsepower = (torque x rpm)/5252

 

[GreaseDog]

A/c signal is programmed to add via IAC. 16 mpg really isnt that great...last trip, I got 17.5 on all 8.
The key here, is to hook up an aldl cable to see whats going on.
I have a sneaking suspicion that the fact that the O2 is now only getting puffs from 2 holes, is richening everything up to 8 cyl spec

I why wouldn't it work? Nothing it's telling the ECM that 4 cylinders are missing. It thinks it's firing a live injector, thinks it's sucking in through 2 bores, and exhaling through 8 exhaust Ports. As stated above, the oxygen sensor looks at quality, not quantity. So long as the manifolds vacuum it's adequate, it shouldn't tryto richen anything anything up, as it should see no issue.

 

[Jims86]

I why wouldn't it work? Nothing it's telling the ECM that 4 cylinders are missing. It thinks it's firing a live injector, thinks it's sucking in through 2 bores, and exhaling through 8 exhaust Ports. As stated above, the oxygen sensor looks at quality, not quantity. So long as the manifolds vacuum it's adequate, it shouldn't tryto richen anything anything up, as it should see no issue.

Ok, whatever....To tell the truth, I dont really give a flying **** anymore.

 

[jpoole]

O2 volts

So long as the manifolds vacuum it's adequate, it shouldn't tryto richen anything anything up, as it should see no issue.

I did some datalogging yesterday and confirmed in closed loop that O2 voltage cycles up and down between .1 and .9 volts

 

[jpoole]

https://www.youtube.com/watch?v=MpNtASxKDV4

 

[HotRodPC]

Yep, harder on the throttle is why the firmer shift.

 

[jpoole]

8 is great

Well it was fun but I was tired of the lack of power so I put the 4 disabled ones back in service. I ran it with 4 for about 1500 miles and there doesn't seem to be any ill effects from doing it.
I also just bought a '90 C3500 for $700 that has a tbi 454. Guess what I'm thinking?

 

[bucket]

Well it was fun but I was tired of the lack of power so I put the 4 disabled ones back in service. I ran it with 4 for about 1500 miles and there doesn't seem to be any ill effects from doing it.
I also just bought a '90 C3500 for $700 that has a tbi 454. Guess what I'm thinking?

Umm, try out a giant 4 cyl?