EFI kill cylinders from CF, anyone??

mrvette

Phantom of the Opera
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Default Custom EFI Idea
I have done some EFI Conversions in the past but I have been thinking. Has anyone come up with a conversion that runs on 8-6-4 concept. I am thinking it should be based on load and anytime there isn't a 20% or better throttle request from the TPS than the ECM uses logrithms to determine if it needs 8-6-4 cylinders to acheive the proper power. It would also rotate the cylinder it powers like the Northstar limp home mode they used when the coolant leaked out. I had a buddy who blew a hose on his and it worked AWESOME he said it didn't ruin the engine and he drove 100 miles home with NO coolant. I just think this technology could be used to keep our cars from getting hot when cruising and that we could drastically improve MPG if we did it. I have a C3 I would like to upgrade but thought you guys might have a source?
Some newer cars have a similar technology which got me to thinking.
-Thanks,
Charlie


GM has several engines that have displacement on demand (DOD) that drop out cylinders based on load. I know Honda and Dodge use similar ideas as well. Why not just swap one of those in? It would probably be easier than trying to program a custom ECM to do it smootly.

In the 80's Cadillac tried to do it with there 4-6-8 engine and it was a disaster. The algorithms are probably much more complicated than you would think. At a minimum you would need a sequential EFI that would allow you to turn off individual injectors. I think the GM engines also partially open both intake and exhaust valves on the dead cylinders to prevent any compression on the stroke.

The LS1's have a limp home mode like the Cadillac you mentioned. They fire every other cylinder every other time.
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mrvette
CF Senior Member

Member Since: Jul 1999
Location: Orange Park Florida

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I too have been wondering the same thing recently....I have a DPFI setup on my 355 roller engine for some years now, and it's the old speed density 1227730 reliable GM computer with aftermarket chip/calpac....

some time ago, I had a loose wire, because I was doing some modification or so, think it was the hydroboost mod....anyway it was the ground side of the driver's FI bank...so the engine ran like total crap of course.....but it DID RUN....and it got me home through the hood, I was not on the freeway or anything higher speed.....

at any rate, it got me thinking about all this stuff, and even with sequential firing I can't see how to kill some cylinders on the banks that have O2 sensors in there, which is just the pass bank in MY case....IF I had a more sophisticated computer in there, and had a O2 sensor on each bank, and sequential firing, I still can't see how to keep the O2 sensor from sensing WAY too much oxygen in the exhaust, which of course there would be....UNLESS like we somehow stopped the intake valves from opening....too much like tooo much to type work for me.....

the electronics I can handle, with programing help, but not that major a mechanical......

but the thing is....the stupid engine ran fairly decent with enough power to pull the local 'hills' and get me home, the thing I worry over is eventually snapping the crank from just using the pass bank and say putting a switch in the driver's bank to kill the injectors ....

I look at the firing order.....7218, 4365 4 corners, 4 middles.... and compare to just the pass bank running....I get

x2x8, 4x6x humm.....2 corners two middles...BUT if I express it another way....it's 2x84x6xx which gotta be ragged as hell on crank harmonics....at SOME engine speed I bet it would tear hell out of the bottom end at BEST, and snap the crank at worst.....so I left the idea alone.....

IF I could get around the O2 sensor being messed up AND/OR program around it, but if subjected to extended excess oxygen at speeds what would that DO to the O2 sensor.....

which comes back to the General killing the compression and all that mechanical crap.....


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Just pull the V-8 out and install a 4cyl,and your gas mileage woes will be over.
I think you are going through way to much work to gain a mile or 2,if fuel economy is that big of a concern maybe you should get one of those Smart cars or something similar.
 
My 2.4L makes 171hp. Probably could run with some L48s.

The 2.0L ecotec makes 260hp and 28mpg.
 
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