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I've been pondering making my monte DoD for an experiment. My drive to work is a now 45 minutes on the highway so I could actually log results to work. My plan was to get a extra injector harness from the wrecker and selecting 2 or 3 cylinders to shut down when I'm in cruise with some toggle switchs in the cab.My miss fire is disabled so it might not even set a code. The 3900 has this and I was going to try and find out what cylinders it cuts out. My fuel economy is nothing to complain about at 28mpg but something higher would be something to brage about with a 288hp v6
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disable a bank of injectors. either 1/3/5 or 2/4/6. that will keep the firing intervals equal.
also, disable closed loop fueling, otherwise the extra air from the "dead" cylinders will cause a LOT of extra fuel to get dumped into the active cylinders. -
Isnt that going to skew your front 02 sensor reading also Just a thought or maybe i am not reading /understanding right And isnt the 3900 VVT ?Comment
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also, true DOD shuts down the cylinders via preventing the lifters from opening the intake valve (and possibly the exhaust valve as well) to reduce pumping losses.Comment
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If closed loop is disabled I wouldn't think the computer would care about the o2 reading. VVT doesn't really have anything to do with DoD but could further improve fuel economy.'89 Firebird, 3500 Turbo, T56, 9-bolt/4.11
'86 Fiero, 3500, 4-speedComment
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Iirc the lifters are not shut down as a ls motor has the same feature, can't imagine how to shut down a mechanical part either.
Closed loop, how could I disable it.... Disconnect the o2 sensor or interrupt a signal wire for it? I'm trying to think of a way to pretty much "flick a switch" once this become "successful"
I would imagine that I would need a lower rpm tourqe cam to see sufficient results, but it's all an experiment, at 2200 rpm (110kph 68mph) I'm making 112 chp iirc so for shit sake, best case scenario I'm making half that @66 chp, should move the car. Doing 60 kph (37 mph) I go into full lockup an idle at 1100 which is pretty sweet if I did 60 for Long distancesLast edited by bob442; 10-24-2012, 09:48 PM.Comment
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i was off a bit.
A solenoid control valve assembly integrated into the engine valley cover contains solenoid valves that provide a pressurized oil signal to specially designed hydraulic roller lifters provided by Eaton Corp. and Delphi. These lifters disable and re-enable exhaust and intake valve operation to deactivate and reactivate engine cylindersComment
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I would exhaust all other means of tuning for fuel economy before thinking about DoD.
There is a reason that GM has phased out DoD.2000 Grand Am GT
2011 Chevy Impala
"The world's best cam combined with a poor set of heads will produce an engine that's a dog. But bolt on a set of great heads even with a poor cam, and that engine will still make great power." ~John LingenfelterComment
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Isn't it just called "active fuel management" now?'89 Firebird, 3500 Turbo, T56, 9-bolt/4.11
'86 Fiero, 3500, 4-speedComment
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They also called it AFM, but that seems to have also been phased out.Originally posted by caffeine View Post2000 Grand Am GT
2011 Chevy Impala
"The world's best cam combined with a poor set of heads will produce an engine that's a dog. But bolt on a set of great heads even with a poor cam, and that engine will still make great power." ~John LingenfelterComment
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I'm just starting to see it in the shop. So it seemed like a good idea. Now I guess it's not worth it. I would have loved to play with it.
I can't think of a way to bump up the fuel economy enough for it to be worth it with out changing cams to a cam with a lower tourqe curve, and I don't plan to do that with this car... Maybe a s10 3400 would get such a treatmentComment
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Don't DD the toy.... That solved my fuel use issues... well until I put shit on my legacy... lol
Got Lope?
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I have a 3900 VVT with DOD on the stand right now. If you want to know something ask... I'll try to answer.
A few interesting observations:
The DOD bank had a lot more carbon deposits on the valves and pistons than the non DOD bank.
The lifters are indeed special and have a cut out 'latch' for lack of better terms that disengages the internals of the lifter via hydraulic pressure.
I'm going to attempt to run this setup beyond 7K RPM and see what happens....
As for mileage (no clue). From what I've heard its worth 2-3 MPG on the highway.
The reason it disappeared isn't because it didn't work, but rather because it isn't needed with direct injection.
I'm sure GM only uses it because the pushrod engines are cheaper... it will be interesting to see if the LS engines with direct injection that (were or are) rumored to be out will have DOD and VVT etc...
It's a neat concept but a headache to mess with. It requires a special cam profile for the DOD cylinders that basically adds a few thousandths extra play pickup in the ramp to remove the 'lash' of the DOD mechanism... So far the only way to get a cam is to order a custom cam....
Any other questions ask.Comment
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"I am not what you so glibly call to be a civilized man. I have broken with society for reasons which I alone am able to appreciate. I am therefore not subject to it's stupid laws, and I ask you to never allude to them in my presence again."Comment
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their updated article mentions AFM as well.Comment
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